- Silver-Catalyzed Intramolecular C-2 Selective Acylation of Indoles with Aldehydes: An Atom-Economical Entry to Indole-Indolone Scaffolds
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A direct annulation reaction of N-(2-formylaryl)indoles has been developed, which can provide a new entry to biologically and medicinally important indole-indolone scaffolds via a silver-catalyzed direct oxidative coupling between aldehyde C H and sp2C H bonds for the first time. Remarkably, this strategy displayed excellent functional group compatibilities, thereby suggesting its wide potential for applications in developing and synthesizing new drug-like compounds containing indole-indolone frameworks. (Figure presented.) .
- Wang, Xiaoxia,Li, Zhongfeng,Cao, Shengli,Rao, Honghua
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- Copper(II)-Promoted Oxidation/[3+2]Cycloaddition/Aromatization Cascade: Efficient Synthesis of Tetrasubstituted NH -Pyrrole from Chalcones and Iminodiacetates
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A simple and highly efficient method for the preparation of tetrasubstituted NH -pyrrole from a wide range of chalcones and diethyl iminodiacetates via a Cu(OAc) 2 -promoted oxidation/[3+2]cycloaddition/aromatization cascade reaction has been developed. This reaction proceeds through dehydrogenations, deamination, and oxidative cyclization, affording the corresponding products in good to excellent yields. This convenient methodology for constructing tetrasubstituted NH -pyrroles has several advantages over existing methods, such as the use of easily accessible chalcones and readily available diethyl iminodiacetates, and mild reaction conditions. A wide range of substrates are tolerated.
- Gao, Jian-Rong,Li, Chao-Dong,Li, Yu-Jin,Lin, Zhang-Qi,Xue, Shuai,Ye, Qing,Zhou, Zi-Chun
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- Application of basic isoreticular nanoporous metal-organic framework: IRMOF-3 as a suitable and efficient catalyst for the synthesis of chalcone
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A highly porous isoreticular metal-organic framework (IRMOF-3) was synthesized and employed as a novel efficient heterogeneous catalyst for the synthesis of chalcone via Claisen-Schmidt condensation. The effects of temperature, catalyst amount and solvent
- Wu, Songhai,Ma, Xin,Ran, Jingyu,Zhang, Yanfei,Qin, Fengxiang,Liu, Yong
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- Ranks of Carbon Leaving Groups in Alkene-forming Elimination
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Carbon leaving groups in alkene-forming eliminations are exceptionally poor and their ranks show no correlation with the pKa of the conjugate carbon acid; the extent of bond cleavage in the transition state is evidently critical in determining rank.
- Varma, Manju,Stirling, Charles J. M.
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- Selective C-C bonds formation, N-alkylation and benzo[d]imidazoles synthesis by a recyclable zinc composite
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Earth abundant metals are much less expensive, promising, valuable metals and could be served as catalysts for the borrowing hydrogen reaction, dehydrogenation and heterocycles synthesis, instead of noble metals. The uniformly dispersed zinc composites were designed, synthesized and carefully characterized by means of XPS, EDS, TEM and XRD. The resulting zinc composite showed good catalytic activity for the N-alkylation of amines with amines, ketones with alcohols in water under base-free conditions, while unsaturated carbonyl compounds could also be synthesized by tuning the reaction conditions. Importantly, it was the first time to realize the synthesis of 2-aryl-1H-benzo[d]imidazole derivatives by using this zinc composite under green conditions. Meanwhile, this zinc catalyst could be easily recovered and reused for at least five times.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Ye, Dongdong,Wang, Dawei
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supporting information
p. 266 - 270
(2021/08/06)
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- Boosting the catalytic performance of zinc linked amino acid complex as an eco-friendly for synthesis of novel pyrimidines in aqueous medium
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Zinc linked amino acid complex, Zn(l-proline)2, is considered as a green catalyst for the synthesis of novel series of pyrimidine derivatives 5a–q. The pyrimidines 5a–q were prepared via two pathways: the first is a one-pot reaction of guanidines 3a–c with aromatic aldehyde 1 and acetophenones 2; and the second one is the reaction of guanidines 3a–c with different chalcones 4a–j in aqueous medium. The simplicity of the operation, the short reaction time, and the high efficiency (97%) are the main advantages of this protocol. Furthermore, the green aspects of this synthetic protocol were further investigated by examining the reusability of Zn(l-proline)2 complex throughout five consecutive cycles without a significant loss of catalytic activity. This new procedure has presented remarkable advantages in terms of safety, simplicity, stability, mild conditions, a short reaction time, excellent yields, and high purities without using any organic solvents.
- Ahmed, Eman A.,Soliman, Ahmed M.M.,Ali, Ali M.,Ali El-Remaily, Mahmoud Abd El Aleem Ali
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- Synthesis of lithium/cesium-Zagronas from zagrosian natural asphalt and study of their activity as novel, green, heterogeneous and homogeneous nanocatalysts in the Claisen–Schmidt and Knoevenagel condensations
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A novel, heterogeneous and homogeneous basic nanocatalysts were synthesized by grafting of lithium and cesium on zagrosian natural asphalt sulfonate (Li/Cs-Zagronas). The activity of these catalysts was examined in the Claisen–Schmidt and Knoevenagel condensations under mild reaction conditions. Li/Cs-Zagronas were characterized by FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, inductively coupled plasma and thermogravimetric analysis techniques. These nanocatalysts were removed by simple filtration and reused several times without any deterioration of activity.
- Soleiman-Beigi, Mohammad,Ghalavand, Saba,Venovel, Hadis Gholami,Kohzadi, Homa
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p. 3267 - 3279
(2021/06/17)
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- Antimicrobial, structure-activity relationship and computational studies of some synthesized chalcone derivatives
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Several chalcones viz. 1,3-diaryl-2-propane-1-one (1a), 3-(4-hydroxy phenyl)-1-phenyl-2-propane-1-one (1b), 3-(4-amino-phenyl)-1-phenyl-2-propane-1-one (1c) and their derivatives 2-ethoxy-4,6-diphenyl-4H-pyran-3-carboxylic acid ethyl ester (2a), 4-(4-hydr
- Badal, Md Mizanur Rahman,Islam, Md Tarikul,Parvin, Reshma,Morol, Md Abul Khaer,Maniruzzaman, Md,Yousuf, Mohammad Abu,Halim, Md Ershad
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p. 644 - 650
(2021/02/27)
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- Pharmacophore hybridization approach to discover novel pyrazoline-based hydantoin analogs with anti-tumor efficacy
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In search for new and safer anti-cancer agents, a structurally guided pharmacophore hybridization strategy of two privileged scaffolds, namely diaryl pyrazolines and imidazolidine-2,4-dione (hydantoin), was adopted resulting in a newfangled series of compounds (H1-H22). Herein, a bio-isosteric replacement of “pyrrolidine-2,5-dione” moiety of our recently reported antitumor hybrid incorporating diaryl pyrazoline and pyrrolidine-2,5-dione scaffolds with “imidazoline-2,4-dione” moiety has been incorporated. Complete biological studies revealed the most potent analog among all i.e. compound H13, which was at-least 10-fold more potent compared to the corresponding pyrrolidine-2,5-dione, in colon and breast cancer cells. In-vitro studies showed activation of caspases, arrest of G0/G1 phase of cell cycle, decrease in the expression of anti-apoptotic protein (Bcl-2) and increased DNA damage. In-vivo assay on HT-29 (human colorectal adenocarcinoma) animal xenograft model unveiled the significant anti-tumor efficacy along with oral bioavailability with maximum TGI 36% (i.p.) and 44% (per os) at 50 mg/kg dose. These findings confirm the suitability of hybridized pyrazoline and imidazolidine-2,4-dione analog H13 for its anti-cancer potential and starting-point for the development of more efficacious analogs.
- Upadhyay, Neha,Tilekar, Kalpana,Loiodice, Fulvio,Anisimova, Natalia Yu.,Spirina, Tatiana S.,Sokolova, Darina V.,Smirnova, Galina B.,Choe, Jun-yong,Meyer-Almes, Franz-Josef,Pokrovsky, Vadim S.,Lavecchia, Antonio,Ramaa
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- Synthesis of chalcone derivatives by phthalhydrazide-functionalized tio2-coated nano-fe3o4 as a new heterogeneous catalyst
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Phthalhydrazide immobilized on TiO2-coated nano Fe3O4 (Fe3O4-P) was synthesized and characterized by FT-IR, XRD, SEM, EDS and VSM analysis. The resulting magnetic nanocatalyst was used as a catalyst for the synthesis of chalcone derivatives which affords the desired products in good to excellent yields. This catalyst can be isolated readily after completion of the reaction by an external magnetite field and reused several times without significant loss of activity.
- Farahi, Mahnaz,Karami, Bahador,Keshavarz, Raziyeh,Nia, Forough Motamedi
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p. 407 - 414
(2021/09/07)
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- Activated charcoal-mediated synthesis of chalcones catalyzed by NaOH in water
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A variety of chalcones were synthesized in good yields by the activated charcoal-mediated aldol reactions between benzaldehydes and acetophenones catalyzed by NaOH in water. 2,6-Bis((E)-benzylidene)cyclohexan-1-ones were prepared by the aldol reactions between benzaldehydes and cyclohexanone. Activated charcoal could be recycled five times without the significant decrease of yields.
- Tanemura, Kiyoshi,Rohand, Taoufik
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supporting information
(2021/02/27)
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- Selective oxidation of alkenes to carbonyls under mild conditions
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Herein, a practical and sustainable method for the synthesis of aldehydes, ketones, and carboxylic acids from an inexpensive olefinic feedstock is described. This transformation features very sustainable and mild conditions and utilizes commercially available and inexpensive tetrahydrofuran as the additive, molecular oxygen as the sole oxidant and water as the solvent. A wide range of substituted alkenes were found to be compatible, providing the corresponding carbonyl compounds in moderate-to-good yields. The control experiments demonstrated that a radical mechanism is responsible for the oxidation reaction.
- Huo, Jie,Xiong, Daokai,Xu, Jun,Yue, Xiaoguang,Zhang, Pengfei,Zhang, Yilan
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supporting information
p. 5549 - 5555
(2021/08/16)
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- Selective C-alkylation Between Alcohols Catalyzed by N-Heterocyclic Carbene Molybdenum
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The first implementation of a molybdenum complex with an easily accessible bis-N-heterocyclic carbene ligand to catalyze β-alkylation of secondary alcohols via borrowing-hydrogen (BH) strategy using alcohols as alkylating agents is reported. Remarkably high activity, excellent selectivity, and broad substrate scope compatibility with advantages of catalyst usage low to 0.5 mol%, a catalytic amount of NaOH as the base, and H2O as the by-product are demonstrated in this green and step-economical protocol. Mechanistic studies indicate a plausible outer-sphere mechanism in which the alcohol dehydrogenation is the rate-determining step.
- Liu, Jiahao,Li, Weikang,Li, Yinwu,Liu, Yan,Ke, Zhuofeng
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supporting information
p. 3124 - 3128
(2021/09/20)
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- Iridium and copper supported on silicon dioxide as chemoselective catalysts for dehydrogenation and borrowing hydrogen reactions
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High active ligand usually plays an important role during catalysis and synthesis chemistry. A new and efficient benzotriazole-pyridinyl-silane ligand (BPS) was designed, and the corresponding iridium and copper catalysts were synthesized and thoroughly characterized by means of EDS, TEM, and XPS. The resulting iridium composite revealed excellent catalytic activity for the reaction of tert-butanesulfinamide with benzyl alcohols, while copper catalyst could realize the synthesis of unsaturated carbonyl compounds through the reaction of benzyl alcohols with ketones. This provided an efficient method for selective synthesis of unsaturated carbonyl compounds from benzyl alcohols and ketones in high yields with good recovery performance.
- Zhu, Guanxin,Duan, Zheng-Chao,Zhu, Haiyan,Qi, Minghui,Wang, Dawei
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- Iridium Complexes as Efficient Catalysts for Construction of α-Substituted Ketones via Hydrogen Borrowing of Alcohols in Water
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Ketones are of great importance in synthesis, biology, and pharmaceuticals. This paper reports an iridium complexes-catalyzed cross-coupling of alcohols via hydrogen borrowing, affording a series of α-alkylated ketones in high yield (86 %–95 %) and chemoselectivities (>99 : 1). This methodology has the advantages of low catalyst loading (0.1 mol%) and environmentally benign water as the solvent. Studies have shown the amount of base has a great impact on chemoselectivities. Meanwhile, deuteration experiments show water plays an important role in accelerating the reduction of the unsaturated ketones intermediates. Remarkably, a gram-scale experiment demonstrates this methodology of iridium-catalyzed cross-coupling of alcohols has potential application in the practical synthesis of α-alkylated ketones.
- Luo, Nianhua,Zhong, Yuhong,Wen, Huiling,Shui, Hongling,Luo, Renshi
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p. 1355 - 1364
(2021/03/03)
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- One-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions: Atom-economic synthesis of selenocarbamates and allyl sulfones
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In many reactions involving selenosulfonate or thiosulfonate, the sulfone group often leaves in form of benzenesulfinic acid or sodium benzenesulfinate. A one-pot two-step reaction of selenosulfonate with isocyanides and allyl alcohol under aqueous conditions to afford selenocarbamates and allyl sulfone compounds is reported. The sulfinic acid as the first-step side product is converted to the allyl sulfone compound by water promoted reaction with allyl alcohol. Water acts as both an oxygen source of selenocarbamates and as a promoter to drive the second step reaction. The reactions have the advantages of mild conditions, green, environment-friendly, and high atomic economy.
- Ai, Jing-Jing,Li, Jian,Ji, Shun-Jun,Wang, Shun-Yi
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supporting information
p. 721 - 724
(2020/07/24)
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- Chemoselective reduction of ?,￠-unsaturated carbonyl and carboxylic compounds by hydrogen iodide
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The selective reduction of ?,￠-unsaturated carbonyl compounds was achieved to produce saturated carbonyl compounds with aqueous HI solution. The introduction of an aryl group at an ? or ￠ position efficiently facilitated the reduction with good yield. The reaction was applicable to compounds bearing carboxylic acids and halogen atoms. Through the investigation of the reaction mechanism, it was found that Michael-type addition of iodide occurred to produce ￠-iodo compounds followed by the reduction of C-I bond via anionic and radical paths.
- Matsumoto, Shoji,Marumoto, Hayato,Akazome, Motohiro,Otani, Yasuhiko,Kaiho, Tatsuo
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p. 590 - 599
(2021/03/29)
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- Method for preparing phenyl propenone compound by catalyzing phenylacetylene through molecular sieve
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The invention belongs to the field of molecular sieve catalysis and organic synthesis, and discloses a method for preparing a phenyl propenone compound by catalyzing phenylacetylene through a molecular sieve, which comprises the following steps: adding a phenylacetylene compound I, aldehyde II and a molecular sieve catalyst into a small reaction kettle without adding an organic solvent and any other assistants; performing stirring to react for 0.25-6 hours under the condition of heating at 30-90 DEG C, cooling the reaction kettle to room temperature, performing diluting with ethyl acetate, andcentrifugally separating the catalyst to obtain the phenyl allyl ketone compound III. The molecular sieve catalyst provided by the invention is H-beta of which the silica-alumina ratios are respectively 14 and 29. The method is simple in reaction process, high in catalytic activity and selectivity, recyclable, environmentally friendly and capable of achieving large-scale industrial production.
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Paragraph 0076-0080
(2021/03/13)
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- Visible light mediated selective oxidation of alcohols and oxidative dehydrogenation of N-heterocycles using scalable and reusable La-doped NiWO4nanoparticles
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Visible light-mediated selective and efficient oxidation of various primary/secondary benzyl alcohols to aldehydes/ketones and oxidative dehydrogenation (ODH) of partially saturated heterocycles using a scalable and reusable heterogeneous photoredox catalyst in aqueous medium are described. A systematic study led to a selective synthesis of aldehydes under an argon atmosphere while the ODH of partially saturated heterocycles under an oxygen atmosphere resulted in very good to excellent yields. The methodology is atom economical and exhibits excellent tolerance towards various functional groups, and broad substrate scope. Furthermore, a one-pot procedure was developed for the sequential oxidation of benzyl alcohols and heteroaryl carbinols followed by the Pictet-Spengler cyclization and then aromatization to obtain the β-carbolines in high isolated yields. This methodology was found to be suitable for scale up and reusability. To the best of our knowledge, this is the first report on the oxidation of structurally diverse aryl carbinols and ODH of partially saturated N-heterocycles using a recyclable and heterogeneous photoredox catalyst under environmentally friendly conditions.
- Abinaya, R.,Balasubramaniam, K. K.,Baskar, B.,Divya, P.,Mani Rahulan, K.,Rahman, Abdul,Sridhar, R.,Srinath, S.
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p. 5990 - 6007
(2021/08/24)
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- Application of 4, 6-dimethyl-2-mercaptopyrimidine bivalent nickel complex in preparation of [alpha]-alkyl ketone
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The invention relates to the field of metal organic chemistry, in particular to application of a 4, 6-dimethyl-2-mercaptopyrimidine bivalent nickel complex in preparation of [alpha]-alkyl ketone, which takes a 4, 6-dimethyl-2-mercaptopyrimidine nickel (II) compound as a catalyst and realizes selective preparation of [alpha]-alkyl ketone through cross-coupling reaction of secondary alcohol and primary alcohol by regulating and controlling reaction conditions. The coupling reaction is carried out in anhydrous toluene in the presence of alkali under the protection of inert gas. The application has the advantages of mild reaction system conditions and wide substrate applicability, and effectively avoids the use of organic phosphine ligands and noble metals.
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Paragraph 0019
(2021/04/07)
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- Flow reactor approach for the facile and continuous synthesis of efficient Pd@Pt core-shell nanoparticles for acceptorless dehydrogenative synthesis of pyrimidines from alcohols and amidines
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Carbon supported Pd@Pt core-shell nanoparticles catalyst was prepared in a flow reactor toachieve enhanced catalytic activities with low Pt loading for the acceptorless dehydrogenative synthesis of pyrimidines. Spectroscopic (XAS analysis) and microscopic (HAADF-STEM) techniques reveled that the core-shell structure was formed by the applied preparation method. The Pd@Pt/PVP (polyvinylpyrrolidone)/C catalyst showed the activity for the three component one pot synthesis of pyrimidines through a series of consecutive reactions including oxidation of alcohols, C[sbnd]C, and C[sbnd]N coupling, followed by heterocyclization and dehydrogenation employing various primary alcohols, secondary alcohols, and amidines. The reaction mechanism on Pd@Pt/PVP/C catalyst was explored by comparison with the control experiments.
- Poly, Sharmin Sultana,Hashiguchi, Yuta,Sultana, Asima,Nakamura, Isao,Shimizu, Ken-ichi,Yasumura, Shunsaku,Fujitani, Tadahiro
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- Sequential Catalytic Functionalization of Aryltriazenyl Aldehydes for the Synthesis of Complex Benzenes
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We demonstrate that aryltriazenes can promote three distinctive types of C-H functionalization reactions, allowing the preparation of complex benzene molecules with diverse substitution patterns. 2-Triazenylbenzaldehydes are shown to be efficient substrates for Rh(I)-catalyzed intermolecular alkyne hydroacylation reactions. The resulting triazene-substituted ketone products can then undergo either a Rh(III)-catalyzed C-H activation, or an electrophilic aromatic substitution reaction, achieving multifunctionalization of the benzene core. Subsequent triazene derivatization provides traceless products.
- Seo, Sangwon,Gao, Ming,Paffenholz, Eva,Willis, Michael C.
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p. 6091 - 6098
(2021/05/29)
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- Iron-Catalyzed Alkyne-Based Multicomponent Synthesis of Pyrimidines under Air
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An iron-catalyzed sustainable, economically affordable, and eco-friendly synthetic protocol for the construction of various trisubstituted pyrimidines is described. A wide range of trisubstituted pyrimidines were prepared using a well-defined, easy to prepare, bench-stable, and phosphine-free iron catalyst featuring a redox-noninnocent tridentate arylazo pincer under comparatively mild aerobic conditions via dehydrogenative functionalization of alcohols with alkynes and amidines.
- Chakraborty, Gargi,Guin, Amit Kumar,Mondal, Rakesh,Paul, Nanda D.,Sarkar, Susmita
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p. 13186 - 13197
(2021/10/01)
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- Boron-catalyzed dehydrative allylation of 1,3-diketones and β-ketone esters with 1,3-diarylallyl alcohols in water
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A metal-free catalytic allylation with atom economy and green environment friendly was developed. Allylic alcohols could be directly dehydrated in water by B(C6F5)3, without using any base additives. The reaction can afford the corresponding monoallylated product in moderate to high yield and has been performed on a gram-scale, and a quaternary carbon center can be constructed for the active methine compounds of 1,3-diketones or β-ketone esters in this process. The product can be further converted, such as the synthesis of tetra-substituted pyrazole compounds, or 1,4-dienes and functionalized dihydropyrans.
- Zhang, Guo-Min,Zhang, Hua,Wang, Bei,Wang, Ji-Yu
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p. 17025 - 17031
(2021/05/25)
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- Catalyst- and acid-free Markovnikov hydration of alkynes in a sustainable H2O/ethyl lactate system
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An efficient and sustainable protocol for the hydration of alkynes has been developed under metal/acid/catalyst/ligand-free conditions in a water/ethyl lactate mixture. The hydrogen-bond network in the ethyl lactate and water mixture plays a crucial and decisive role in activating the alkynes for hydration to afford the corresponding methyl ketones. This strategy gives the Markovnikov (ketone) addition product selectively over other possible products. The essential role of hydrogen bonding has been confirmed by experimental and theoretical techniques. A probable mechanism has been suggested by various control tests. The efficacy of the method has been further explored for the competent production of value-added α,β-unsaturated carbonyl compounds through the reaction of aldehydes with alkynes as ketonic surrogates. The environmentally benign hydration method takes place under mild conditions, has broad functional-group compatibility, and uses the ethyl lactate/water (1:3) medium as a “green alternative” in the absence of any hazardous, harmful, or expensive substances.
- Dandia, Anshu,Saini, Pratibha,Chithra,Vennapusa, Sivaranjana Reddy,Parewa, Vijay
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- Immobilized Pd on a NHC-functionalized metal-organic FrameworkMIL-101(Cr): An efficient heterogeneous catalyst in the heck and copper-free Sonogashira coupling reactions
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A heterogeneous palladium catalyst system based on immobilization of palladium moieties on a N-heterocyclic carbene (NHC) modified metal organic framework (MOF) was developed for the Heck and copper-free Sonogashira coupling reactions. In order to prepare this catalyst system, first, MIL-101(Cr) was functionalized with NHC moieties through a post synthetic modification (PSM) approach, and then Pd metal was stabilized on the prepered MIL-101(Cr)-NHC substrate. This material was characterized using various microscopic and spectroscopic techniques and then was used as an efficient heterogeneous Pd catalyst system in the Heck and copper-free Sonogashira reactions. Results of the heterogeneity tests showed that the Pd-NHC-MIL-101(Cr) catalyst can efficiently catalyzed these coupling reactions heterogeneously and no remarkable changes observed in the morphology and structure of MIL-101(Cr) template during the reaction progress. Also, existence of palladium nanoparticles immobilized on the MOF structure affirmed by the TEM and XPS analysis confirmed the oxidation state of Pd. A variety of alkene and alkyne derivatives were synthesized in good to excellent yields using this heterogeneous Pd catalyst system under normal conditions. More importantly Pd-NHC-MIL-101(Cr) catalyst was simply recovered from the reaction medium without remarkable decreasing in its catalytic activities after five times of reusability. The ICP analysis showed the very low Pd and Cr metals leaching, representing high stability and applicability of this catalyst in Pd coupling reactions.
- Niknam, Esmaeil,Panahi, Farhad,Khalafi-Nezhad, Ali
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supporting information
(2021/01/12)
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- Rapid umpolung Michael addition of isatin N, N ′-cyclic azomethine imine 1,3-dipoles with chalcones
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The umpolung Michael addition of isatin N,N′-cyclic azomethine imine 1,3-dipoles with chalcones is reported. The reaction could be finished within a very short time (0.3-2 min), with 3,3-disubstituted oxindole derivatives obtained in moderate to excellent yields with promising dr values. Unusual Michael adducts were obtained in moderate to high yields (26-98%) with low to high diastereoselectivities (0.8: 1 to 8.5: 1 dr). All the synthesized compounds (3, 3′, 4, 5, 5′, 7, 7′, 9 and 9′) were well characterized by FTIR, NMR, and mass spectral analyses and further confirmed by the single-crystal X-ray diffraction analysis of compounds 3aa and 4n.
- Yue, Guizhou,Jiang, Dan,Dou, Zhengjie,Li, Sicheng,Feng, Juhua,Zhang, Li,Chen, Huabao,Yang, Chunping,Yin, Zhongqiong,Song, Xu,Liang, Xiaoxia,Wang, Xianxiang,Lu, Cuifen
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p. 11712 - 11718
(2021/07/12)
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- Synthesis of Kr?hnke pyridines through iron-catalyzed oxidative condensation/double alkynylation/amination cascade strategy
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An efficient protocol for the synthesis of symmetrical and unsymmetrical 2,4,6-trisubstituted pyridines via oxidative cascade annulation of arylacetylenes with benzylamines has been developed. The reaction proceeds smoothly utilizing iron(II) triflate as a catalyst and molecular oxygen as an oxidant with broad substrate scope. Mechanistic studies reveal that the reaction may be experiences an oxidative condensation followed by double alkynylation and amination process.
- Gopalaiah, Kovuru,Choudhary, Renu
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supporting information
(2021/09/15)
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- Chromium carbides and cyclopropenylidenes
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Carbon tetrabromide can be reduced with CrBr2in THF to form a dinuclear carbido complex, [CrBr2(thf)2)][CrBr2(thf)3](μ-C), along with formation of [CrBr3(thf)3]. An X-ray diffraction (XRD) study of the pyridine adduct displayed a dinuclear structure bridged by a carbido ligand between 5- and 6-coordinate chromium centers. The carbido complex reacted with two equivalents of aldehydes to form α,β-unsaturated ketones. Treatment of the carbido complex with alkenes resulted in a formal double-cyclopropanation of alkenes by the carbido moiety to afford spiropentanes. Isotope labeling studies using a13C-enriched carbido complex, [CrBr2(thf)2)][CrBr2(thf)3](μ-13C), identified that the quaternary carbon in the spiropentane framework was delivered by carbide transfer from the carbido complex. Terminal and internal alkynes also reacted with the carbido complex to form cyclopropenylidene complexes. A solid-state structure of the diethylcyclopropenylidene complex, prepared from 3-hexyne, showed a mononuclear cyclopropenylidene chromium(iii) structure.
- Irifune, Keiichi,Kurogi, Takashi,Takai, Kazuhiko
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p. 14281 - 14287
(2021/11/12)
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- Site-Selective Acceptorless Dehydrogenation of Aliphatics Enabled by Organophotoredox/Cobalt Dual Catalysis
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The value of catalytic dehydrogenation of aliphatics (CDA) in organic synthesis has remained largely underexplored. Known homogeneous CDA systems often require the use of sacrificial hydrogen acceptors (or oxidants), precious metal catalysts, and harsh reaction conditions, thus limiting most existing methods to dehydrogenation of non- or low-functionalized alkanes. Here we describe a visible-light-driven, dual-catalyst system consisting of inexpensive organophotoredox and base-metal catalysts for room-temperature, acceptorless-CDA (Al-CDA). Initiated by photoexited 2-chloroanthraquinone, the process involves H atom transfer (HAT) of aliphatics to form alkyl radicals, which then react with cobaloxime to produce olefins and H2. This operationally simple method enables direct dehydrogenation of readily available chemical feedstocks to diversely functionalized olefins. For example, we demonstrate, for the first time, the oxidant-free desaturation of thioethers and amides to alkenyl sulfides and enamides, respectively. Moreover, the system's exceptional site selectivity and functional group tolerance are illustrated by late-stage dehydrogenation and synthesis of 14 biologically relevant molecules and pharmaceutical ingredients. Mechanistic studies have revealed a dual HAT process and provided insights into the origin of reactivity and site selectivity.
- Zhou, Min-Jie,Zhang, Lei,Liu, Guixia,Xu, Chen,Huang, Zheng
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supporting information
p. 16470 - 16485
(2021/10/20)
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- A Remote ‘Imidazole’-Based Ruthenium(II) Para-Cymene Pre-catalyst for the Selective Oxidation Reaction of Alkyl Arenes and Alcohols
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Herein we disclosed the use of a remote ‘imidazole’-based precatalyst [(para-cymene)RuII(L)Cl]+, C-1 where L=2-(4-substituted-phenyl)-1H-imidazo[4,5-f][1,10] phenanthroline) for the selective oxidation of a variety of alkyl arenes/heteroarenes and alcohols to their corresponding aldehydes or ketones in presence of tert-butyl hydroperoxide (TBHP). The remote ‘imidazole’ moiety present in the complex facilitates the activation of oxidant and subsequent generation of active species via the release of para-cymene from C-1, which in-turn was less effective without the ‘imidazole’ moiety. The mechanistic features of C-1 promoted oxidation of alkyl arenes were also assessed from spectroscopic, kinetic, and few control experiments. The substrate scope for C-1 promoted oxidation reaction was assessed based on the selective oxidation of 27-different alkyl arenes/heteroarenes and 25 different alcohols to their corresponding aldehydes/ketones in moderate to good yields.
- Dutta, Manali,Bania, Kusum K.,Pratihar, Sanjay
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p. 926 - 932
(2020/03/05)
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- Silica-supported heterogeneous catalysts-mediated synthesis of chalcones as potent urease inhibitors: in vitro and molecular docking studies
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Abstract: We herein report a facile and high yielding protocol for silica-supported heterogeneous catalysts-mediated synthesis of chalcones. A comparison of results of our synthesis with conventional synthetic protocols is also being offered to assess the efficiency of the prepared catalysts. Biological evaluation of the newly synthesized compounds as urease inhibitors was performed. Most of the compounds were found to have potent urease inhibition activity. The chalcone 3-(3-hydroxyphenyl)-1-phenylpropenone was found to be the most potent with percentage inhibition 86.17 ± 0.89 and half maximal inhibitory concentration (IC50) value 11.51 ± 0.03 μM. The molecular docking study emphasized that the same congeners 3-(furan-2-yl)-1-(4-hydroxyphenyl)propenone, 3-(4-hydroxyphenyl)-1-(4-methoxyphenyl)propanone, and 3-[4-(dimethylamino)phenyl]-1-(p-tolyl)propenone showed very good inhibitory potential against urease and show a higher docking scores 5718, 5940, 5596 and an ACE of ? 246.66, ? 244.79, and ? 243.06 kJ/mol, respectively than the control ligand. Graphic abstract: [Figure not available: see fulltext.].
- Sultan, Aeysha,Shajahan, Shanavas,Ahamad, Tansir,Alshehri, Saad M.,Sajjad, Noreen,Mehr-un-Nisa,Rehman, Mian Habib Ur,Torun, Lokman,Khalid, Muhammad,Acevedo, Roberto
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p. 123 - 133
(2020/01/11)
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- Synthesis method of chalcone derivative
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The invention provides a synthesis method of a chalcone derivative, which comprises the following steps: adding polyphosphoric acid PPA and a solvent 1, 4-dioxane into a container, sequentially adding98% concentrated sulfuric acid, substituted benzaldehyd
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Paragraph 0054-0056; 0081; 0082; 0088
(2020/07/03)
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- Potassium Natural Asphalt Sulfonate (K-NAS): Synthesis and characterization as a new recyclable solid basic nanocatalyst and its application in the formation of carbon–carbon bonds
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In this research, we synthesized and characterized a new heterogeneous basic nanocatalyst and its catalytic application was studied in the Claisen-Schmidt and Knoevenagel condensations. In order to prepare this nanocatalyst, first, the Iranian natural asphalt was sulfonated with the concentrated sulfuric acid and then, converted to the potassium natural asphalt sulfonate (K-NAS). In order to characterization of the nanocatalyst, used of FT-IR spectroscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), inductively coupled plasma (ICP) and thermogravimetric analysis (TGA) techniques. This new basic heterogeneous nanocatalyst have advantages such as being eco-friendly, huge specific surface area, high reactivity and recyclability.
- Falah, Saeid,Soleiman-Beigi, Mohammad,Kohzadi, Homa
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- Biocatalytic green alternative to existing hazardous reaction media: Synthesis of chalcone and flavone derivatives via the Claisen-Schmidt reaction at room temperature
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Owing to the increasing amount of waste materials around the globe, the conversion of waste or secondary by-products to value-added products for various applications has gained significant interest. Herein, two novel agro-food waste products, Musa sp. 'Malbhog' peel ash (MMPA) and Musa Champa Hort. ex Hook. F. peel ash (MCPA) are used as catalysts to promote an inexpensive, efficient and eco-friendly carbon-carbon bond forming crossed aldol reaction at room temperature in solvent free conditions. Furthermore, the resulting products were subjected to reactions with these promoters in an oxygen atmosphere and led to the formation of novel flavone derivatives. Moreover, the used catalysts were properly characterized using different sophisticated analytical techniques such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller analysis (BET), Raman spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), transition electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) along with element detection using atomic absorption spectroscopy and ion chromatographic methods. These two approaches are metal free, as well as being devoid of any extra additives, co-catalysts, harsh conditions, the use of column chromatography for purification and result in a higher yield of the product within a short space of time. The catalytic abilities of the promoter were also examined to synthesize important bioactive molecules such as butein and apigenin at room temperature. With gram scale synthesis of the chalcone derivatives, the used catalysts (MMPA and MCPA) were further reused for five cycles and did not demonstrate any loss in catalytic activity.
- Tamuli, Kashyap J.,Sahoo, Ranjan K.,Bordoloi, Manobjyoti
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supporting information
p. 20956 - 20965
(2020/12/31)
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- Method for catalytically synthesizing chalcone by heteropolyacid
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The invention relates to a method for synthesizing chalcone. The method comprises the following specific steps: adding acetophenone, benzaldehyde, a ternary heteropolyacid catalyst H4[Ti(H2O)TiW11O39].7H2O and 95% ethanol into a three-necked bottle provid
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Paragraph 0015-0017
(2020/07/02)
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- Synthesis and Biological Evaluation of Pyrazoline and Pyrrolidine-2,5-dione Hybrids as Potential Antitumor Agents
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In search of novel and effective antitumor agents, pyrazoline-substituted pyrrolidine-2,5-dione hybrids were designed, synthesized and evaluated in silico, in vitro and in vivo for anticancer efficacy. All the compounds exhibited remarkable cytotoxic effects in MCF7 and HT29 cells. The excellent antiproliferative activity toward MCF7 (IC50=0.78±0.01 μM), HT29 (IC50=0.92±0.15 μM) and K562 (IC50=47.25±1.24 μM) cell lines, prompted us to further investigate the antitumor effects of the best compound S2 (1-(2-(3-(4-fluorophenyl)-5-(p-tolyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxoethyl)pyrrolidine-2,5-dione). In cell-cycle analysis, S2 was found to disrupt the growth phases with increased cell population in G1/G0 phase and decreased cell population in G2/M phase. The excellent in vitro effects were also supported by inhibition of anti-apoptotic protein Bcl-2. In vivo tumor regression studies of S2 in HT29 xenograft nude mice, exhibited equivalent and promising tumor regression with maximum TGI, 66 % (i. p. route) and 60 % (oral route) at 50 mg kg?1 dose by both the routes, indicating oral bioavailability and antitumor efficacy. These findings advocate that hybridization of pyrazoline and pyrrolidine-2,5-dioes holds promise for the development of more potent and less toxic anticancer agents.
- Anisimova, Natalia Y.,Choe, Jun-yong,Lavecchia, Antonio,Loiodice, Fulvio,Meyer-Almes, Franz-Josef,Pokrovsky, Vadim S.,S Ramaa, C.,Smirnova, Galina B.,Sokolova, Darina V.,Spirina, Tatiana S.,Tilekar, Kalpana,Upadhyay, Neha
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p. 1813 - 1825
(2020/09/07)
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- The Use of Modified Clay as an Efficient Heterogeneous and Ecofriendly Catalyst for the Synthesis of Chalcones via Claisen-Schmidt Condensation
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Abstract: Clay modified by potassium fluoride (KF-modified clay) was used as an ecological alternative and heterogeneous catalyst for the preparation of chalcones via Claisen-Schmidt condensation. In this paper, we have synthesized classical chalcones by condensation of benzaldehyde substituents with acetophenone. Moreover, the other chalcones were also synthesized during the condensation of benzaldehyde substituents with 2-acetylfuran. All the results obtained show that our material can be used as an effective catalyst for the synthesis of chalcones with good yield included between 90 and 99%. The catalyst recycle study shows that the modified clay can be reused four times without a decrease in catalytic activity.
- Bentahar, S.,Dbik, A.,Khomri, M. El,Lacherai, A.,Messaoudi, N. El,Sabour, A.,Taleb, M. Ait
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p. 983 - 990
(2020/08/24)
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- Unsaturated ketone compound as well as preparation method and application thereof
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The present invention relates to a novel GPR52 antagonist. Specifically, the invention relates to an unsaturated ketone compound, a pharmaceutically acceptable salt, a stereoisomer or a prodrug molecule thereof, and a method for preparing a pharmaceutical composition thereof. The invention further relates to the use of the GPR52 antagonist as an orphan G protein coupled receptor GPR52 antagonist,and further relates to the use of the GPR52 antagonist in the preparation of drugs for preventing and treating Huntington's disease.
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Paragraph 0219-0222
(2020/10/30)
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- Iron(ii)-folded single-chain nanoparticles: a metalloenzyme mimicking sustainable catalyst for highly enantioselective sulfa-Michael addition in water
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Metalloenzyme is a source of inspiration for chemists who attempt to create versatile synthetic catalysts for aqueous catalysis. Herein, we impart metalloenzyme-like characteristics to a chiral FeII-oxazoline complex by incorporating an Fe(ii) ion into a chiral oxazoline-containing discrete self-folded polymer, to realize highly enantioselective sulfa-Michael addition (SMA) in water. Intrachain FeII-oxazoline complexation together with hydrophobic interactions triggers the self-folding of the oxazoline-containing single polymeric chain in water. The formed FeII-folded single-chain polymeric nanoparticles (SCPNs) significantly accelerate the aqueous asymmetric SMA reaction via a self-folded hydrophobic compartment around the catalytic sites, reminiscent of metalloenzymatic catalysis. In addition, they can be facilely recovered for reuse by simple thermo-controlled separation due to their thermo-responsive properties. Such metallo-folded SCPNs combine the benefits of transition metal- and bio-catalyst, and avoid the tedious procedures of separation, which is a benefit for energy-saving and industrial applications.
- Li, Chaoping,Li, Shiye,Tan, Rong,Wang, Jiajun,Wang, Weiying,Yin, Donghong
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supporting information
p. 4645 - 4655
(2020/08/10)
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- Cyclometalated pt complexes of cnc pincer ligands: Luminescence and cytotoxic evaluation
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In the framework of our attempts to develop cyclometalated Pt(II) complexes toward bifunctional targeting inhibitors or agents for photodynamic therapy, diagnostics, and bioimaging, a series of bis-cyclometalated Pt(II) complexes [Pt(CNC)(L)] (L = DMSO, MeCN) containing various (CNC)2- ligands based on 2,6-diphenylpyridine were synthesized and characterized analytically and spectroscopically, focusing on their electrochemical, luminescence, and antiproliferative properties. Electrochemical experiments and UV-vis absorption spectroscopy suggest ligand-centered LUMOs and metal-centered HOMOs in line with DFT calculations. Extension of the ancillary phenyl to naphthyl cores and a central 4-phenylpyridine group instead of pyridine results in bathochromic shifts of the long-wavelength absorption bands ranging from 420 to 440 nm, with the latter shift being more pronounced. The complexes of the fused CNC heterocyclic systems dba (H2dba = dibenzo[c,h]acridine), db(ph)a (H2db(ph)a = 7-phenyldibenzo[c,h]acridine), and bzqph (HbzqphH = 2-phenylbenzo[h]quinoline) absorb far more red-shifted in the range 500-530 nm. All complexes show reversible first electrochemical reductions and irreversible oxidations with an electrochemical gap of about 3 V, roughly in line with the absorption energies. While the 2,6-diphenylpyridine complexes [Pt(CNC)(DMSO)] show no luminescence at ambient temperature in solution, the fused dba, db(ph)a, and bzqph derivatives are efficient triplet emitters at ambient temperature with emission wavelengths in the region 575-600 nm and quantum yields ranging from 7 to 23%. Vibrationally resolved emission spectra calculated in the framework of DFT faithfully reproduce the experimental data. TD-DFT calculations at the excited-state T1 geometry reveal intraligand π-π*/MLCT character of the emission for all three investigated complexes. Antiproliferative tests on selected complexes gave very different toxicities, ranging from lower than 1 μM to virtually nontoxic. The data allowed drawing some structure-activity relationships (SAR), even though variations in solubility could also significantly account for the different toxicities.
- Garbe, Simon,Krause, Maren,Klimpel, Annika,Neundorf, Ines,Lippmann, Petra,Ott, Ingo,Brünink, Dana,Strassert, Cristian A.,Doltsinis, Nikos L.,Klein, Axel
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supporting information
p. 746 - 756
(2020/03/30)
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- N-para-sulfonium salt substituted pyrazoline derivative, photocurable composition and preparation method
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The invention relates to an N-para-sulfonium salt substituted pyrazoline derivative shown as the following formula (I) in the specification, a photocurable composition, and a preparation method of theN-para-sulfonium salt substituted pyrazoline derivative shown as the following formula (I). The N-para-sulfonium salt substituted pyrazoline derivative shown as formula (I) has good absorption at a wavelength of 350nm or above, and compared with a 5-substituted sulfonium salt, the N-para-sulfonium salt substituted pyrazoline derivative has the advantages of simpler and more convenient molecule synthesis steps and reduced cost of raw materials, and is more suitable for industrial production and application.
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Paragraph 0142-0144; 0148-0149
(2020/07/21)
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- Upconversion NIR-II fluorophores for mitochondria-targeted cancer imaging and photothermal therapy
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NIR-II fluorophores have shown great promise for biomedical applications with superior in vivo optical properties. To date, few small-molecule NIR-II fluorophores have been discovered with donor-acceptor-donor (D-A-D) or symmetrical structures, and upconversion-mitochondria-targeted NIR-II dyes have not been reported. Herein, we report development of D-A type thiopyrylium-based NIR-II fluorophores with frequency upconversion luminescence (FUCL) at ~580 nm upon excitation at ~850 nm. H4-PEG-PT can not only quickly and effectively image mitochondria in live or fixed osteosarcoma cells with subcellular resolution at 1 nM, but also efficiently convert optical energy into heat, achieving mitochondria-targeted photothermal cancer therapy without ROS effects. H4-PEG-PT has been further evaluated in vivo and exhibited strong tumor uptake, specific NIR-II signals with high spatial and temporal resolution, and remarkable NIR-II image-guided photothermal therapy. This report presents the first D-A type thiopyrylium NIR-II theranostics for synchronous upconversion-mitochondria-targeted cell imaging, in vivo NIR-II osteosarcoma imaging and excellent photothermal efficiency.
- Zhou, Hui,Zeng, Xiaodong,Li, Anguo,Zhou, Wenyi,Tang, Lin,Hu, Wenbo,Fan, Quli,Meng, Xianli,Deng, Hai,Duan, Lian,Li, Yanqin,Deng, Zixin,Hong, Xuechuan,Xiao, Yuling
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- Effect of substituents in the A and B rings of chalcones on antiparasite activity
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Chalcones are a group of natural products with many recognized biological activities, including antiparasitic activity. Although a lot of chalcones have been synthetized and assayed against parasites, the number of structural features known to be involved in this biological property is small. Thus, in the present study, 21 chalcones were synthesized to determine the effect of substituents in the A and B rings on the activity against Leishmania braziliensis, Trypanosoma cruzi, and Plasmodium falciparum. The compounds were active against L. braziliensis in a structure-dependent manner. Only one compound was very active against T. cruzi, but none of them had a significant antiplasmodial activity. The electron-donating substituents in ring B and the hydrogen bonds at C-2′ with carbonyl affect the antiparasitic activity.
- González, Luis A.,Upegui, Yulieth A.,Rivas, Luis,Echeverri, Fernando,Escobar, Gustavo,Robledo, Sara M.,Qui?ones, Wiston
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- Tuning the Product Selectivity of the α-Alkylation of Ketones with Primary Alcohols using Oxidized Titanium Nitride Photocatalysts and Visible Light
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The direct α-alkylation of ketones with alcohol to synthesize important α-alkylated ketones and enones is an attractive procedure for C-C bond formation. High reaction temperatures are always needed for heterogeneous catalysis using non-noble metals, and switching product selectivity in one catalysis system remains a great challenge. In the present study, a visible-light-driven procedure for this reaction is proposed, using oxidized TiN photocatalysts under mild conditions, whereby the product selectivity can be well-tuned. Oxidized TiN photocatalysts with tunable surface N/O ratios were successfully synthesized through the facile and flexible thermal oxidation treatment of low-cost TiN nanopowder. The α-alkylation of acetophenone with benzyl alcohol to form the two important compounds chalcone and dihydrochalcone occurred even at room temperature and almost complete conversion was achieved at 100 °C under visible light. The proportion of the two products can be well-tuned by switching the surface N/O ratio of the synthesized photocatalysts. Visible light is demonstrated to affect the surface N/O ratio of the photocatalysts and contribute to tuning the product selectivity. Light intensity and action spectrum study proves that the generation of energetic charge carriers results in the observed activities under visible light, based on interband transitions of TiN or the ligand-to-metal charge transfer (LMCT) effect of the surface complex formed on TiO2. Thermal energy can be coupled with light energy within this photocatalytic system, which will facilitate the full use of solar energy. Different sequential reaction mechanisms on TiN and TiO2 are proposed to be responsible for the tunable product selectivity. The wide reaction scope, the fine conversion at a low light intensity, and the favorable reusability of photocatalysts prove the great application potential of this visible-light-driven procedure for the α-alkylation of ketones with primary alcohols.
- Li, Peifeng,Su, Haijia,Xiao, Gang,Zhao, Yilin
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p. 3640 - 3649
(2020/04/09)
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- Iodine-catalyzed α,β-dehydrogenation of ketones and aldehydes generating conjugated enones and enals
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A transition metal-free α,β-dehydrogenation of ketones and aldehydes was developed. This reaction was conducted in a facile I2/KI/DMSO system to produce the corresponding unsaturated compounds in good to high yields. The gram-scale experiment also indicated the potential synthetic value of this new reaction in organic synthesis. In the reaction, DMSO acted as both solvent and mild oxidant.
- Cao, Yuanjie,Chen, Tieqiao,Huang, Tianzeng,Liu, Long
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p. 8697 - 8701
(2020/06/08)
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- Donor-acceptor fluorophores as efficient energy transfer photocatalysts for [2 + 2] photodimerization
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Mild [2 + 2] photodimerization of enone substrates was induced by donor-acceptor fluorophores. Enone substrates were activated efficiently for anti-head to head dimerizations with a high yield (up to 83%) and high selectivity. The adjustable excited state potential also allows donor-acceptor fluorophores to be used for isomerization of the above substrates, confirming the potential of donor-acceptor fluorophores as energy transfer photocatalysts.
- Chen, Feng,Chen, Hao,Liu, Xue-Fen,Luo, Shu-Ping,Ren, Chen-Chao,Wu, Qing-An,Xu, Liang-Xuan,Yu, Xiao-Cong
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supporting information
p. 3707 - 3716
(2020/06/03)
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- Ligand-tuned cobalt-containing coordination polymers and applications in water
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Ligands play a key role in modern catalysis research and occasionally determine whether a reaction will take place under specific conditions, such as in water. In this experiment, ligands containing an indole-based diacid moiety were employed to prepare the corresponding cobalt coordination polymer material (Co-CIA) and porous oval polymer material (Co-NCIA). Interestingly, it was observed that Co-CIA could promote the alkylation of ketones with alcohols and alcohols with alcohols, while Co-NCIA was effective for the synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazoles from various phenylenediamine and benzyl alcohols through borrowing hydrogen and dehydrogenation strategies. Other mechanism explorations, such as deuterium labeling experiments and a kinetics study, were conducted to better understand Co-CIA and Co-NCIA systems and the related transformations. Our studies provided an efficient method for the development of highly active cobalt coordination polymer materials with excellent recovery performance for dehydrogenation and borrowing hydrogen reactions under water and base-free conditions.
- Tao, Rong,Yang, Yike,Zhu, Haiyan,Hu, Xinyu,Wang, Dawei
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supporting information
p. 8452 - 8461
(2020/12/29)
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- Fabrication of Copper-based Silica-coated Magnetic Nanocatalyst for Efficient One-pot Synthesis of Chalcones via A3 Coupling of Aldehydes-Alkynes-Amines
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In the present work, we have synthesized bioactive and pharmacologically important chalcone motifs by employing green and efficient silica-coated magnetically separable catalyst, Cu@DBM@ASMNPs. The highly proficient nanocatalyst proves its invincibility f
- Yadav, Priya,Yadav, Manavi,Gaur, Rashmi,Gupta, Radhika,Arora, Gunjan,Rana, Pooja,Srivastava, Anju,Sharma, Rakesh K.
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p. 2488 - 2496
(2020/03/26)
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- CeO2-Supported Pd(II)-on-Au Nanoparticle Catalyst for Aerobic Selective α,β-Desaturation of Carbonyl Compounds Applicable to Cyclohexanones
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Direct selective desaturation of carbonyl compounds to synthesize α,β-unsaturated carbonyl compounds represents an environmentally benign alternative to classical stepwise procedures. In this study, we designed an ideal CeO2-supported Pd(II)-on-Au nanoparticle catalyst (Pd/Au/CeO2) and successfully achieved heterogeneously catalyzed selective desaturation of cyclohexanones to cyclohexenones using O2 in air as the oxidant. Besides cyclohexenones, various bioactive enones can also be synthesized from the corresponding saturated ketones under open air conditions in the presence of Pd/Au/CeO2. Preliminary mechanistic studies revealed that α-C-H bond cleavage in the substrates is the turnover-limiting step of this desaturation reaction.
- Jin, Xiongjie,Mizuno, Noritaka,Takei, Daisuke,Yabe, Tomohiro,Yamaguchi, Kazuya,Yatabe, Takafumi
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p. 5057 - 5063
(2020/05/27)
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- Iodine/water-mediated deprotective oxidation of allylic ethers to access α,β-unsaturated ketones and aldehydes
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The first iodine/water-mediated deprotective oxidation of allylic ethers to access α,β-unsaturated ketones and aldehydes was achieved. The reaction tolerates a wide range of functionalities. Furthermore, this protocol was found to be applicable to the oxidative transformation of allylic acetates. The proposed mechanism involves an oxygen transfer from solvent water to the carbonyl products.
- Chen, Weifeng,Jiang, Kezhi,Xue, Yuntian,Yan, Yaolong,Yang, Lei
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p. 14720 - 14724
(2020/04/27)
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- Catalytic activity of Mg-Al hydrotalcites and derived mixed oxides for imination reactionsviaan oxidative-dehydrogenation mechanism
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The catalytic activities of Mg-Al hydrotalcites and derived Mg-Al mixed oxides were studied for the imination of benzylic substrates (benzyl amine and benzyl alcohol), with aniline as a model reaction, to establish a green and cost-effective catalytic (precious metal free) process for imination and tandem reactions utilizing alcohols as reagents. The Mg-Al mixed oxide (Mg/Al ratio = 3.0) was found to be an efficient catalyst for imination reactions to synthesize cross-imines with high selectivity as well as for tandem reactions of alcohols. Basic sites of catalysts adsorb benzylic substrates through the hydrogen of their functional groups (-NH2/-OH) and activate (weaken) benzylic C-H bonds for hydride elimination. Thus, basic sites catalyze the reaction by activating benzylic substrates for oxidative-dehydrogenation (i.e., deprotonation followed by hydride elimination with the help of oxygen) to produce reactive imine/carbonyl intermediates, which undergo subsequent nucleophilic reactions with amine.
- Vala, Naresh,Joshi, Pradyuman A.,Mishra, Manish
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p. 8859 - 8868
(2020/06/08)
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- Gold-catalyzed partial hydrogenation of activated alkynes mediated by triphenylphosphine
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Gold(I) can exhibit a cooperative effect with triphenylphosphine, accelerating the triphenylphosphine-mediated partial hydrogenation of activated alkynes. In this protocol, 3-arylpropiolates are selectively reduced to the Z -isomer when the aryl ring bears an electron-donor substituent, whereas 3-arylpropynones are reduced to the E-isomers.
- Cocoletzi-Xochitiotzi, Ana Patricia,Hernández-Hernández, Miguel,Medina-Mercado, Ignacio,Jiménez-Martínez, Williams De Jesús,Mastranzo, Virginia Maricela,Porcel, Susana
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supporting information
p. 2379 - 2386
(2020/08/19)
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