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Solid Molecular Frustrated Lewis Pairs in a Polyamine Organic Framework for the Catalytic Metal-free Hydrogenation of Alkenes
We report for the first time a metal-free heterogeneously catalyzed hydrogenation using a semi-solid frustrated Lewis pair (FLP). The catalyst consists of a solid polyamine organic framework and molecular tris(pentafluorophenyl)borane (BCF) that form a semi-immobilized FLP in situ in the catalytic hydrogenation of diethyl benzylidenemalonate. 11B NMR spectroscopy proves the successful hydrogen activation by the FLP. Furthermore, the B?N interactions between the polyamine and BCF are investigated by IR and solid state NMR spectroscopy. The FLP 1,4-diazabicyclo[2.2.2]octane (DABCO)/BCF, which combines the features of a FLP and a classical Lewis adduct, functions as molecular reference in both, catalysis and characterization. Furthermore, computational studies enable a better insight into the hydrogen activation through DABCO/BCF and polyamine/BCF.
Willms, Andrea,Schumacher, Hannah,Tabassum, Tarnuma,Qi, Long,Scott, Susannah L.,Hausoul, Peter J. C.,Rose, Marcus
p. 1835 - 1843
(2018)
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Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
supporting information
p. 2085 - 2094
(2021/09/02)

FRUSTRATED LEWIS PAIR-IMPREGNATED POROUS MATERIALS AND USES THEREOF
Described herein are compositions composed of frustrated Lewis pairs impregnated in porous materials such as, for example, metal-organic frameworks, and their uses thereof. These compositions may allow new applications of frustrated Lewis pairs in catalysis by sequestering and protecting the frustrated Lewis pair within the nanospace of the porous material. Also provided are methods of hydrogenating an organic compound having at least one unsaturated functional group comprising using the compositions described herein.
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(2021/01/23)

Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
Topf, Christoph,Vielhaber, Thomas
(2021/07/10)

Validating the 1,2-Difluoro Motif As a Hybrid Bioisostere of CF3and et Using Matrix Metalloproteinases As Structural Probes
Matrix metalloproteinases (MMPs) are involved in a spectrum of physiological processes, rendering them attractive targets for small-molecule drug discovery. Strategies to achieve selective inhibition continue to be intensively pursued, facilitated by advances in structural biology. Herein, we harness MMPs 2, 8, 9, and 13 to validate the vicinal difluoro motif as a hybrid bioisostere of CF3 and Et (BITE) in a series of modified barbiturate inhibitors. Crystallographic analyses of representative structures reveal conformations of the vicinal difluoro motif that manifest stabilizing hyperconjugative interactions consistent with the stereoelectronic gauche effect. Detailed docking studies of a potent difluorinated probe with MMP-9 are also disclosed and indicate that the structural basis of inhibition is a consequence of the anisotropic nature of the motif. Significant selectivity of MMP 13 versus MMP-2 can be achieved by subtle chain contraction in a BITE-modified inhibitor.
Erdeljac, Nathalie,Thiehoff, Christian,Jumde, Ravindra P.,Daniliuc, Constantin G.,H?ppner, Sandra,Faust, Andreas,Hirsch, Anna K. H.,Gilmour, Ryan
p. 6225 - 6237
(2020/07/14)

Synthesis of protected α-amino acids: Via decarboxylation amination from malonate derivatives
A general and efficient strategy for the synthesis of protected α-amino acids is reported. The method uses malonate derivatives as the starting materials and Cs2CO3 as a base at 60 degrees, giving α-amino acid derivatives in moderate yields by releasing CO2. This methodology shows broad substrate scope (primary and secondary acids), excellent functional group tolerance and high efficiency to give the desired products under mild reaction conditions. It also allows the construction of β and γ-amino acids and other unnatural products.
Dai, Qipu,Fu, Hui,Hu, Changwen,Li, Peihe,Li, Xiaoying,Wang, Zheng
p. 4439 - 4446
(2020/10/20)

FLP-catalysis meets hydrogen-bond activation
The potential of two chiral amidines and three non-chiral boranes in the metal-free hydrogen activation was explored. The resulting chiral amidiunium borohydride salts were investigated in asymmetric hydrogenation reactions of ketimines, activated double bonds and dehydro amioacid esters.
K?ring, Laura,Paradies, Jan,Roesky, Peter W.,Sitte, Nikolai A.
supporting information
p. 7321 - 7325
(2020/10/13)

Enantioselective α-Amination of Acyclic 1,3-Dicarbonyls Catalyzed by N-Heterocyclic Carbene
Herein, we describe a method for the catalytic enantioselective α-amination of α-substituted acyclic 1,3-ketoamides and 1,3-amidoesters that affords the products possessing N-substituted quaternary stereocenters with a chiral N-heterocyclic carbene (NHC). The reaction is based on the utilization of an intrinsic Br?nsted base characteristic of NHC that enables the catalytic formation of a chiral ion pair comprising the enolate and the azolium ion. A series of challenging open-chain α-substituted 1,3-dicarbonyls are aminated via this method with ee's of ≤99%.
Santra, Surojit,Maji, Ujjwal,Guin, Joyram
supporting information
p. 468 - 473
(2020/02/04)

Environmentally benign nucleophilic substitution reaction of arylalkyl halides in water using CTAB as the inverse phase transfer catalyst
An environmentally benign, practically scalable and highly selective C-arylalkylation of active methylene compounds is developed using CTAB as the inverse phase transfer catalyst in water. The methodology developed is elaborated into the one-pot synthesis of quinoline derivatives and also applicable to the regioselective N-aralkyl of 2-pyridones.
Godha, Atul K.,Thiruvengadam, Jayaraman,Abhilash, Viswanadhan,Balgi, Prajwal,Narayanareddy,Vignesh, Kumaresan,Gadakh, Amol V.,Sathiyanarayanan,Ganesh, Sambasivam
supporting information
p. 16041 - 16045
(2019/10/28)

Aryltrifluoromethylative cyclization of unactivated alkenes by the use of PhICF3Cl under catalyst-free conditions
A concise and catalyst-free aryltrifluoromethylative cyclization of unactivated alkenes has been developed herein. The use of PhICF3Cl as a powerful trifluoromethylating agent allows easy transformations. A set of trifluoroethylated carbocycles and aza-hereocycles were efficiently synthesized in good yield and selectivity. A broad substrate scope, mild reaction conditions, and easy operation would make this method well-suited for applications.
Guo, Jia,Xu, Cong,Liu, Xiaowei,Wang, Mang
supporting information
p. 2162 - 2168
(2019/02/27)

Novel Old Yellow Enzyme Subclasses
Many drug candidate molecules contain at least one chiral centre, and consequently, the development of biocatalytic strategies to complement existing metal- and organocatalytic approaches is of high interest. However, time is a critical factor in chemical process development, and thus, the introduction of biocatalytic steps, even if more suitable, is often prevented by the limited availability of off-the-shelf enzyme libraries. To expand the biocatalytic toolbox with additional ene reductases, we screened 19 bacterial strains for double bond reduction activity by using the model substrates cyclohexanone and carvone. Overall, we identified 47 genes coding for putative ene reductases. Remarkably, bioinformatic analysis of all genes and the biochemical characterization of four representative novel ene reductases led us to propose the existence of two new Old Yellow Enzyme subclasses, which we named OYE class III and class IV. Our results demonstrate that although, on a DNA level, each new OYE subclass features a distinct combination of sequence motifs previously known from the classical and the thermophilic-like group, their substrate scope more closely resembles the latter subclass.
Peters, Christin,Frasson, David,Sievers, Martin,Buller, Rebecca
p. 1569 - 1577
(2019/05/15)

Pd-Catalyzed C—S Cyclization via C—H Functionalization Strategy: Access to Sulfur-containing Benzoheterocyclics
A C—H sulfurated cyclization protocol starting from thioacetates is developed for straightforward construction of sulfur-containing benzoheterocyclics. The diversiform functional dihydrobenzothiophenes and thiochromans were comprehensively achieved through the Pd-catalyzed carbon- sulfur cyclization. Mechanistic studies indicated that C—H bond cleavage was involved in the rate-determining step. [1]Benzothieno-[3,2-b]- [1]benzothiophene (BTBT) and benzo[b]thieno[2,3-d]thiophene (BTT) were efficiently established as the well-known organic field-effect transistor (OFET) material molecules through this methodology.
Chen, Shihao,Wang, Ming,Jiang, Xuefeng
supporting information
p. 921 - 924
(2018/09/22)

Biocatalytic Desymmetrization of Prochiral 3-Aryl and 3-Arylmethyl Glutaramides: Different Remote Substituent Effect on Catalytic Efficiency and Enantioselectivity
Catalyzed by an amidase-containing Rhodococcus erythropolis AJ270 microbial whole cell catalyst in neutral phosphate buffer at 30 °C, desymmetric hydrolysis of a series of prochiral 3-aryl and 3-arylmethylglutaramides efficiently afforded 3-substituted glutaric acid monoamides in up to 95% yield and >99.5% ee. Even far away from the reaction site, the substituents on the aryl still have a significant effect on the catalytic activity and enantioselectivity and different remote substituent effect was observed for the two types of substrates. The synthetic application of biocatalytic desymmetrization was demonstrated by the facile transformation of the obtained enantiopure (R)-3-substituted 4-carbamoylbutanoic acid products to chiral dihydroquinolinone and δ-lactone compounds. (Figure presented.).
Ao, Yu-Fei,Zhang, Li-Bin,Wang, Qi-Qiang,Wang, De-Xian,Wang, Mei-Xiang
supporting information
p. 4594 - 4603
(2018/10/31)

Metal-Organic Framework Anchored with a Lewis Pair as a New Paradigm for Catalysis
Lewis pair (LP) chemistry has shown broad applications in the catalysis field. However, one significant challenge has been recognized as the instability for most homogeneous LP catalysts upon recycling, thus inevitably leading to dramatic loss in catalytic activity. Additionally, current heterogeneous LP catalysts suffer from low surface area, which largely limits their catalytic efficiency, thereby restricting their potential applications. In this work, we report the successful introduction of LPs, classical and frustrated, into a metal-organic framework (MOF) that features high surface and ordered pore structure via a stepwise anchoring strategy. Not only can the LP be stabilized by the strong coordination interaction between the LP and MOF, but the resultant MOF-LP also demonstrates excellent catalysis performance with interesting size and steric selectivity. Given the broad applicability of LPs, our work therefore paves a way for advancing MOF-LP as a new paradigm for catalysis. Lewis pairs (LPs), classical and frustrated, are excellent prospects in catalysis, organic syntheses, biology, and material sciences. However, the instability of most LP catalysts leads to a dramatic loss in activities, thereby largely restricting their industrial applications. As robust porous materials, metal-organic frameworks (MOFs) offer a platform to stabilize homogeneous catalysts. Here, we show a strategy that grafts the LP catalyst on the MOF to minimize loss of LPs during catalysis and recycling. Our work reveals the enormous potential of MOFs as an appealing paradigm for the construction of efficient heterogeneous catalysts with interesting steric and size selectivity worthy of exploration. In addition, the strategies for anchoring a LP into a MOF as contributed herein can be readily applied for the task-specific design of functional catalysis materials for various applications. Lewis pairs (LPs), classical and frustrated, have been successfully introduced into and stabilized in a metal-organic framework (MOF). Benefiting from the robust framework and tunable porous structure of MOFs, the resultant MOF-LP demonstrates not only great recyclability but also excellent performance in the catalytic reduction of imines and hydrogenation of alkenes. The combination of LP and MOF therefore lays a foundation for developing a MOF-LP as a new paradigm for catalysis, particularly heterogeneous catalysis.
Niu, Zheng,Bhagya Gunatilleke, Wilarachchige D.C.,Sun, Qi,Lan, Pui Ching,Perman, Jason,Ma, Jian-Gong,Cheng, Yuchuan,Aguila, Briana,Ma, Shengqian
supporting information
p. 2587 - 2599
(2018/12/02)

Synthesis and insecticidal activity of mesoionic pyrido[1,2-α]pyrimidinone derivatives containing a neonicotinoid moiety
Mesoionic pyrido[1,2-α]pyrimidinone derivatives containing a neonicotinoid moiety were designed, synthesized, and evaluated for their insecticidal activity. Some of the title compounds showed remarkable insecticidal properties against Aphis craccivora. Compound I13 exhibited satisfactory insecticidal activity against A. craccivora. Meanwhile, label-free proteomics analysis of compound I13 treatment identified a total of 821 proteins. Of these, 35 proteins were up-regulated, whereas 108 proteins were down-regulated. Differential expressions of these proteins reflected a change in cellular structure and metabolism.
Pan, Jianke,Yu, Lu,Liu, Dengyue,Hu, Deyu
(2018/05/30)

Reactivity of benzylidene and alkylidenemalonates in radical addition mediated with dialkylzincs – An intriguing story
Benzylidene- and alkylidenemalonates are extremely reactive radical acceptors in dialkylzinc-mediated radical additions. Theoretical investigations showed that the multi-step radical-polar crossover process should be highly exothermic. Not only the addition of the alkyl radical to the complexed substrate is enthalpically favored but what is more, the homolytic substitution at the metal leading to a zinc enolate should also be exothermic, even though it necessitates the cleavage of the C-Zn bond from the complexed α-alkoxycarbonyl radical intermediate. This work was undertaken to highlight the power of chelation in controlling the fate of this type of reaction. Much to our surprise, no unambiguous experimental evidence could be put forward to prove the formation of the expected zinc enolate intermediate. Additionally, benzylidenemalonates and their alkylidene analogues (although to a lesser extent) exhibit an intriguing behavior. The backward reaction (retro-addition) can be triggered at work-up depending upon experimental conditions.
Lingua, Hugo,Dwadnia, Nejib,Siri, Didier,Bertrand, Michèle P.,Feray, Laurence
supporting information
p. 7507 - 7515
(2018/11/27)

Room Temperature, Reductive Alkylation of Activated Methylene Compounds: Carbon-Carbon Bond Formation Driven by the Rhodium-Catalyzed Water-Gas Shift Reaction
The rhodium-catalyzed water-gas shift reaction has been demonstrated to drive the reductive alkylation of several classes of activated methylene compounds at room temperature. Under catalysis by rhodium trichloride (2-3 mol %), carbon monoxide (10 bar), water (2-50 equiv), and triethylamine (2.5-7 equiv), the scope has been successfully expanded to cover a wide range of alkylating agents, including aliphatic and aromatic aldehydes, as well as cyclic ketones, in moderate to high yields. This method is comparable to, and for certain aspects, surpasses the established reductive alkylation protocols.
Denmark, Scott E.,Ibrahim, Malek Y. S.,Ambrosi, Andrea
p. 613 - 630
(2017/06/05)

A novel bifunctional Pd-ZIF-8/rGO catalyst with spatially separated active sites for the tandem Knoevenagel condensation-reduction reaction
A novel bifunctional catalyst with spatially separated active sites was prepared by the immobilization of Pd nanoparticles (NPs) via covalent interaction and coordination of a zeolitic imidazolate framework (ZIF-8) on the surface of graphene oxide (GO), respectively, which was used as an efficient catalyst for the Knoevenagel condensation-reduction tandem reaction. The results of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) demonstrated that Pd and ZIF-8 were successfully immobilized on the surface of GO, and the GO was reduced to reduced graphene oxide (rGO) using NaBH4 as the reductant in the preparation of Pd-ZIF-8/rGO. The textural properties and morphology of Pd-ZIF-8/rGO were characterized by N2 adsorption-desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Pd-ZIF-8/rGO shows excellent catalytic performance in the tandem reaction with 100% benzaldehyde conversion and 98.3% selectivity to benzylmalononitrile. The excellent catalytic performance of Pd-ZIF-8/rGO in the tandem reaction is due to the high catalytic activities of spatially separated Pd NPs and ZIF-8 active sites and concentrated reactants on the surface of Pd-ZIF-8/rGO due to the π-π interaction between rGO and the reactants. The anchoring and stabilization effects of oxygenated groups of GO inhibit the aggregation and leakage of active sites, leading to good catalytic recyclability with almost unchanged catalytic activity for more than eight cycles in the tandem reaction.
Wang, Hefang,Wang, Yansu,Jia, Aizhong,Wang, Cunyue,Wu, Luming,Yang, Yongfang,Wang, Yanji
p. 5572 - 5584
(2017/12/07)

Photocatalytic function of the B12 complex with the cyclometalated iridium(III) complex as a photosensitizer under visible light irradiation
A visible light induced three-component catalytic system with the cobalamin derivative (B12) as a catalyst, the cyclometalated iridium(iii) complex (Irdfppy, Irppy, Irpbt and [Ir{dF(CF3)ppy}2(dtbpy)]PF6) as a photosensitizer and triethanolamine as an electron source under N2 was developed. This catalytic system showed a much higher catalytic efficiency than the previous catalytic system using [Ru(ii)(bpy)3]Cl2 as the photosensitizer for the dechlorination reaction of 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT). Noteworthy is the fact that the remarkable high turnover number (over ten thousand) based on B12, which ranks at the top among the reported studies, was obtained when Irdfppy was used as a photosensitizer. This photocatalytic system was also successfully applied to the B12 enzyme-mimic reaction, i.e., the 1,2-migration of the phenyl group of 2-bromomethyl-2-phenylmalonate. The plausible reaction mechanism was proposed, which involved two quenching pathways, an oxidative quenching pathway and a reductive quenching pathway, to be responsible for the initial electron transfer of the excited-state photosensitizers during the DDT dechlorination reaction. Transient photoluminescence experiments revealed that the oxidative quenching of the photosensitizer dominated over the reductive quenching pathway.
Tian, Hui,Shimakoshi, Hisashi,Park, Gyurim,Kim, Sinheui,You, Youngmin,Hisaeda, Yoshio
p. 675 - 683
(2018/02/16)

Reprint of: Impact of the corrin framework of vitamin B12 on the electrochemical carbon-skeleton rearrangement in comparison to an imine/oxime planar ligand; tuning selectivity in 1,2-migration of a functional group by controlling electrolysis potential
Among the coenzyme B12-dependent enzymes, methylmalonyl-CoA mutase (MMCM) catalyzes the carbon-skeleton rearrangement reaction between R-methylmalonyl-CoA and succinyl-CoA. Diethyl 2-bromomethyl-2-phenylmalonate, an alkyl bromide substrate having two different migrating groups (phenyl and carboxylic ester groups) on the β-carbon, was applied to the electrolysis mediated by a hydrophobic vitamin B12 model complex, heptamethyl cobyrinate perchlorate in this study. The electrolysis of the substrate at ? 1.0 V vs. Ag-AgCl by light irradiation afforded the simple reduced product (diethyl 2-methyl-2-phenylmalonate) and the phenyl migrated product (diethyl 2-benzyl-2-phenylmalonate), as well as the electrolysis of the substrate at ? 1.5 V vs. Ag-AgCl in the dark. The electrolysis of the substrate at ? 2.0 V vs. Ag-AgCl afforded the carboxylic ester migrated product (diethyl phenylsuccinate) as the major product. The selectivity for the migrating group was successfully tuned by controlling the electrolysis potential. We clarified that the cathodic chemistry of the Co(III) alkylated heptamethyl cobyrinate is critical for the selectivity of the migrating group through mechanistic investigations and comparisons to the simple vitamin B12 model complex, an imine/oxime-type cobalt complex.
Abe, Masaaki,Hisaeda, Yoshio,Pan, Ling,Shimakoshi, Hisashi,Tahara, Keishiro,Yamaguchi, Ryoko
p. 438 - 443
(2017/10/23)

Diastereoselective synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones via SmI2-mediated reductive coupling of 2-alkylacrylates of N,N-diisopropyl-2-hydroxybenzamide with aldehydes
Samarium(II) diiodide has been used to mediate reductive coupling reactions of aldehydes with a variety of substituted acrylates, in both achiral and chiral forms, for accessing substituted dihydrofuran-2(3H)-ones (γ-butyrolactones). Two major issues, concerning with self-dimerization of α-non-branched aliphatic aldehydes and low diastereoselectivity of the products, render limited application of the reductive coupling protocol in total synthesis of natural products. We report here on a novel type of substituted acrylates derived from the 2-amido arenols (HO-Aram) such as N,N-diisopropyl-2-hydroxybenzamide. The acrylates of HO-Aram enable: (a) preferential conjugate reduction of the acrylates than carbonyl reduction of aliphatic aldehydes, leading to diminished aldehyde self-dimerization; and (b) organization of an eight-membered ring among the amide carbonyl oxygen atom and samarium(III) to form a 7/8-bicyclic transition state, resulting in highly diastereoselective protonation of the samarium(III) enolate intermediate. Examples of synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones from 2-alkylacrylates of HO-Aram and aliphatic aldehydes are provided.
Lai, Yecai,Sun, Lijie,Sit, Man Ki,Wang, Yan,Dai, Wei-Min
p. 664 - 673
(2016/01/15)

Synthesis and activity evaluation of the cyclic dipeptides arylidene N-alkoxydiketopiperazines
A series of arylidene N-alkoxydiketopiperazines was designed and stereoselectively synthesized via oxime-ether formation and intramolecular acylation. Possible cyclization and acid-catalyzed rearrangement-fragmentation mechanisms were discussed. The crystal structure of the novel diketopiperazine further confirmed the rearrangement mechanism. Most compounds exhibited antitumor activity. Several compounds were more potent against caspase-3. Specifically, compounds 6e, 6g, and 6f inhibited caspase-3 at IC50values lying within the low micromolar range and demonstrated good selectivity. The binding modes of alkoxydiketopiperazines in the active center of caspase-3 were also discussed based on the molecular docking results.
Tian, Xia,Feng, Juan,Fan, Shi-ming,zhen, Xiao-li,Han, Jian-rong,Liu, Shou-xin
p. 5197 - 5205
(2016/10/24)

Nano-K2CO3: Preparation, characterization and evaluation of reactive activities
A novel base, nano-K2CO3, was easily prepared by ultrafine wet milling. The surface properties and the reactive activities of nano-K2CO3 were characterized. It was found that such a base showed higher basicity than normal K2CO3 and could replace sodium (or potassium) alkoxide to carry out monoalkylation and oximation of active methylene compounds. The nano-K2CO3 could be regenarated and reused 10 times without loss of its reactive activity.
Li, Jun-Zhang,Fan, Shi-Ming,Sun, Xuan-Fei,Liu, Shouxin
p. 1865 - 1869
(2016/01/20)

Synthesis method of propafenone drug intermediate benzyl malonic acid diethyl ester
A synthesis method of propafenone drug intermediate benzyl malonic acid diethyl ester comprises the following steps: adding 4.6mol of diethyl malonate, 0.13mol of cuprous chloride, 13.6mol of sodium sulfite solution and 310ml of nitromethane into a reaction container provided with a stirrer, a thermometer and a dropping funnel, controlling a stirring speed at 130-160rpm, rising a solution temperature to 60--65 DEG C, adding 5.1-5.3mol of benzyl amine, after adding, reacting for 30-35h, separating out solid, filtering, washing a filter cake with a salt solution, washing with cyclohexane, distilling under reduced pressure, collecting a fraction of 90-95 DEG C, recrystalizing in acetonitrile to obtain a crystal benzyl malonic acid ethyl ester.
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(2016/11/14)

Creation through immobilization: A new family of high performance heterogeneous bifunctional iminophosphorane (BIMP) superbase organocatalysts
An immobilized chiral bifunctional iminophosphorane superbase organocatalyst has been developed and applied in a range of challenging enantioselective reactions. A unique feature of this novel catalytic system is that the final step creation of the iminophosphorane occurs at the point of immobilization. The utility of the immobilized catalyst system was demonstrated in the nitro-Mannich reaction of ketimines as well as the conjugate addition of high pKa 1,3-dicarbonyl pro-nucleophiles to nitrostyrene. Catalyst recycling was also demonstrated.
Goldys, Anna M.,Nez, Marta G.,Dixon, Darren J.
supporting information
p. 6294 - 6297
(2015/02/05)

Gallium-assisted transfer hydrogenation of alkenes
We report a rare case of alkene transfer hydrogenation using a main-group compound instead of a transition-metal complex as catalyst. We disclosed that 1, 4-cyclo-hexadiene can be used as H2 surrogate towards olefin reduction in the presence of [IPrGaCl2][SbF6]. Hydrogenative cycli-zations have also been carried out because this cationic gallium complex is also a potent hydroarylation catalyst.
Michelet, Bastien,Bour, Christophe,Gandon, Vincent
supporting information
p. 14488 - 14492
(2015/04/16)

Copper hydride-catalyzed reduction of electron-deficient olefins
Copper hydride derived from CuF(PPh3)3·2MeOH- bis[(2-diphenylphosphino)phenyl] ethersilane can reduce electron-deficient olefins selectively and efficiently.
Zheng, Ai-Jun,Shan, Feng-Jun,Li, Zheng-Ning,Li, Zeng-Chang,Jiang, Lan
p. 1271 - 1276
(2013/07/19)

Functional-group tolerance in frustrated lewis pairs: hydrogenation of nitroolefins and acrylates
Weak Lewis acid for high nucleophilicity: Hydridoborate derived from B(2,6-F2C6H3)3 shows significant hydride character. Solid-state and solution structure analysis revealed a dihydrogen-bonded aggregate. The new frustrated Lewis pair was applied in the hydrogenation of nitroolefins and acrylates (see scheme; EWG=electron- withdrawing group). The decreased Lewis acidity provides higher reactivity and functional-group tolerance. Copyright
Greb, Lutz,Daniliuc, Constantin-Gabriel,Bergander, Klaus,Paradies, Jan
supporting information
p. 5876 - 5879
(2013/07/05)

Tuning the lewis acidity of boranes in frustrated lewis pair chemistry: Implications for the hydrogenation of electron-poor alkenes
An analysis of the metal-free reduction of electron deficient olefins by frustrated Lewis pairs indicates that the rate-determining step might be either the heterolytic cleavage of H2 to form an -onium borohydride salt, or the subsequent transfer of the hydride moiety to the substrate following a Michael-type addition reaction. While the use of strong Lewis acids such as B(C6F5)3 facilitates the first of these processes, hydride transfer to the olefin should be contrarily favoured by the use of weak Lewis acids which, for this very same reason, might be unable to promote the prior H2 split. After systematic testing of several boranes of different Lewis acidity (assessed by using the Childs' method) and steric demand, an optimal situation that employs tris(2,4,6-trifluorophenyl) borane was reached. Mixtures of this borane with 1,4-diazabicyclo[2.2.2]octane (DABCO) exhibited excellent catalytic activity for the hydrogenation of alkylidene malonates. In fact, this transformation could be achieved under milder conditions than those we reported previously. Moreover, the reaction scope could be expanded to other electron deficient olefins containing esters, sulfones or nitro functionalities as electron-withdrawing substituents.
Nicasio, Juan A.,Steinberg, Sebastian,Ines, Blanca,Alcarazo, Manuel
p. 11016 - 11020
(2013/09/02)

Overturning established chemoselectivities: Selective reduction of arenes over malonates and cyanoacetates by photoactivated organic electron donors
The prevalence of metal-based reducing reagents, including metals, metal complexes, and metal salts, has produced an empirical order of reactivity that governs our approach to chemical synthesis. However, this reactivity may be influenced by stabilization of transition states, intermediates, and products through substrate-metal bonding. This article reports that in the absence of such stabilizing interactions, established chemoselectivities can be overthrown. Thus, photoactivation of the recently developed neutral organic superelectron donor 5 selectively reduces alkyl-substituted benzene rings in the presence of activated esters and nitriles, in direct contrast to metal-based reductions, opening a new perspective on reactivity. The altered outcomes arising from the organic electron donors are attributed to selective interactions between the neutral organic donors and the arene rings of the substrates.
Doni, Eswararao,Mondal, Bhaskar,O'Sullivan, Steven,Tuttle, Tell,Murphy, John A.
supporting information
p. 10934 - 10937
(2013/08/23)

First iodine-catalyzed deallylation of reactive allyl methylene esters
C-Allyl cleavage has been developed using the inexpensive and mild reagent iodine in dimethylsulfoxide. A variety of compounds with active methylene groups were C-deallylated using this reagent. This method is efficient and operationally simple in comparison to the methods using transition-metal complexes. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
Nawghare, Beena R.,Lokhande, Pradeep D.
p. 1955 - 1963
(2013/06/05)

Metal-free hydrogenation of electron-poor allenes and alkenes
The poorer, the better: A metal-free catalytic procedure for the reduction of electron-poor allenes and alkenes has been developed. The method employs a frustrated Lewis pair based catalyst. 1,4-Diazabicyclo[2.2.2]octane (DABCO)/B(C6F5)3 was shown to be the best combination in optimization studies. Copyright
Ines, Blanca,Palomas, David,Holle, Sigrid,Steinberg, Sebastian,Nicasio, Juan A.,Alcarazo, Manuel
supporting information
p. 12367 - 12369
(2013/02/22)

Aromatic-amide-derived olefins as a springboard: Isomerization-initiated palladium-catalyzed hydrogenation of olefins and reductive decarbonylation of acyl chlorides with hydrosilane
A highly efficient catalytic protocol for the isomerization of substituted amide-derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl2(PPh3)2] and HSi(OEt)3. The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis-trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide-derived olefin ligand, and the products were obtained in high isolated yields (up to >99 %). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)-olefin with an aromatic amide moiety was used as a ligand. Copyright
Bai, Xing-Feng,Xu, Li-Wen,Zheng, Long-Sheng,Jiang, Jian-Xiong,Lai, Guo-Qiao,Shang, Jun-Yan
supporting information; experimental part
p. 8174 - 8179
(2012/08/27)

Pd(II)-catalyzed intramolecular amidoarylation of alkenes with molecular oxygen as sole oxidant
Stereoselective palladium-catalyzed synthesis of structurally versatile indoline derivatives, using molecular oxygen as the sole oxidant, is described. New C-N and C-C bonds form across an alkene in an intramolecular manner. The C-N bond-forming step proceeds via a syn-amidopalladation pathway. The moderate kinetic isotope effects (intramolecular KIE = 3.56) suggest that electrophilic aromatic substitution occurs in the arylation step.
Yip, Kai-Tai,Yang, Dan
supporting information; experimental part
p. 2134 - 2137
(2011/06/19)

The non-metathetic role of Grubbs' carbene complexes: From hydrogen-free reduction of α,β-unsaturated alkenes to solid-supported sequential cross-metathesis/reduction
An efficient and high-yielding "hydrogen-free" reduction of α,β-unsaturated alkenes was carried out employing Grubbs' catalyst in a non-metathetic role and Et3SiH. Conditions were optimized under microwave irradiation. Application to the solid-phase organic synthesis allows a facile construction of sp3-sp3 carbon bonds through a sequential cross metathesis/olefin reduction.
Poeylaut-Palena, Andres A.,Testero, Sebastian A.,Mata, Ernesto G.
supporting information; experimental part
p. 1565 - 1567
(2011/03/20)

Nucleophilic dearomatization of chloromethyl naphthalene derivatives via η3-benzylpalladium intermediates: A new strategy for catalytic dearomatization
Palladium-catalyzed nucleophilic dearomatization of chloromethyl naphthalene derivatives to produce ortho- or para-substituted carbocycles in satisfactory to excellent yields has been developed. The unprecedented dearomatization reactions proceeded smoothly under mild conditions via η3-benzylpalladium intermediates.
Peng, Bo,Zhang, Sheng,Yu, Xiaoqiang,Feng, Xiujuan,Bao, Ming
supporting information; experimental part
p. 5402 - 5405
(2011/12/03)

Monoalkylations with alcohols by a cascade reaction on bifunctional solid catalysts: Reaction kinetics and mechanism
A bifunctional catalytic system formed by Pd on MgO catalyzes the cascade process between benzyl alcohol and phenylacetonitrile, diethylmalonate and nitromethane, to give the respective α-monoalkylated products without external supply of hydrogen. The process involves a series of three cascade reactions occurring on different catalytic sites. The alcohol undergoes oxidation to the corresponding aldehyde with the simultaneous formation of a metal hydride; then, the aldehyde reacts with a nucleophile formed "in situ" to give an alkene, and finally, the hydrogen from the hydride is transferred to the alkene to give a new C-C bond. A kinetic study on the α-monoalkylation reaction of benzylacetonitrile with benzyl alcohol reveals that the rate-controlling step for the one-pot reaction sequence is the hydrogen transfer reaction from the surface hydrides to the olefin, and consequently, the global reaction rate is improved when decreasing the size of the Pd metal particle.
Corma, Avelino,Rodenas, Tania,Sabater, Maria J.
experimental part
p. 319 - 327
(2011/05/14)

Electrochemical catalytic carbon-skeleton rearrangement mediated by imine/oxime-type B12 model complex
An electrochemical carbon-skeleton rearrangement of methylmalonate skeleton to succinate was successfully mediated by an imine/oxime-type cobalt complex using diethyl 2-bromomethyl-2- phenylmalonate as a model substrate of a coenzyme B12-dependent enzymatic reaction. Cyclic voltammetric and mass spectrometric studies revealed that this electrocatalysis of the alkyl bromide with 1,2-migration of a carboxylic ester group was achieved by the duet redox process between the reduction of the monoalkylated complex and the oxidation of the dialkylated complex.
Tahara, Keishiro,Chen, Yi,Pan, Ling,Masuko, Takahiro,Shimakoshi, Hisashi,Hisaeda, Yoshio
p. 177 - 179
(2011/04/14)

Practical synthesis of diethyl phenylsuccinate by Mg-promoted carboxylation of ethyl cinnamate
Mg-promoted reduction of ethyl cinnamate (1a) in the presence of carbon dioxide gave a mixture of β-carboxylated compound 2a and α,β-dicarboxylated compound 3a. Similar reductive carboxylation of 1a followed by acidic decarboxylation of one of the two geminal carboxyl groups of the generated 3a and esterification afforded selective formation of diethyl phenylsuccinate (2a) in good yield.
Maekawa, Hirofumi,Murakami, Taro,Miyazaki, Takeshi,Nishiguchi, Ikuzo
scheme or table
p. 368 - 369
(2011/05/04)

Zinc-mediated alkylation and acylation of 1,3-dicarbonyl compounds
1,3-Dicarbonyl compounds undergo smooth allylation, benzylation, propargylation, and acylation with halides using metallic zinc in DMF at 60 °C to afford the corresponding allyl, benzyl, 2-propynyl, and acylated 1,3-diesters in good yields. In the case of cyclic 1,3-diketones, the corresponding enol ethers are obtained as sole products instead of C-alkylation.
Yadav,Reddy, B. V. Subba,Mishra, Anand Kumar
experimental part
p. 280 - 281
(2010/09/05)

Rapid and regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester catalyzed by titanium tetrachloride
A regioselective hydrogenation of α,β-unsaturated ketones and alkylidene malonic diesters using Hantzsch ester as the reducing agent and titanium tetrachloride as a catalyst is described. The short reaction times and mild reaction conditions are the advantages of this method. Georg Thieme Verlag Stuttgart New York.
Che, Jun,Lam, Yulin
experimental part
p. 2415 - 2420
(2010/11/19)

Selective sulfenylative desulfonylation or decarbalkoxylation of α-sulfonyl malonates with DABCO or Bu3N: Reactivity and conformational analysis
The study on reactivity of severalαsubstituted αsulfonyl malonates toward 1,4-diazabicyclo[2.2.2]octane (DABCO) and Bu3N is described. The reactivity with DABCO revealed the possible competition between decarbalkoxylation and unexpected desulfonylation, depending on the-substituent, because of sterical hindrance around the electrophilic centers (SO2 and CO2R). The derivatives with crowded α-substituents suffer selective desulfonylation, and a novel and efficient desulfonylation method can be proposed. The dependence of the reactivity ofα-sulfonyl malonates on the sterical hindrance around the electrophilic centers is confirmed by conformational analysis (Macromodel/MM2* and Mopac/MP3). The carbanionic mechanism is proved because the corresponding protonated, deuterated, and sulfenylated products were obtained by addition of the corresponding electrophilic agents. Bu3N showed itself to be a novel selective decarbalkoxylation agent for any-substituted-sulfonyl malonate.
Donnici, Claudio L.,Pereira, Elaine Henriques Teixeira,Lopes, Julio C. Dias,Marzorati, Liliana,Wladislaw, Blanka
experimental part
p. 342 - 350
(2010/04/04)

Preparation and reactivity of vitaminB12-TiO2 hybrid catalyst immobilized on a glass plate
The vitaminB12-TiO2 hybrid catalyst was effectively immobilized on a glass plate, and the immobilized catalyst shows an efficient reactivity for various molecular transformations, such as the 1,2-migration of a phenyl group and dechlorination of perchloroethylene during irradiation by UV light.
Shimakoshi, Hisashi,Abiru, Makoto,Kuroiwa, Keita,Kimizuka, Nobuo,Watanabe, Midori,Hisaeda, Yoshio
experimental part
p. 170 - 172
(2010/05/15)

TETRAHYDRO ISOQUINOLINE DERIVATIVES, PREPARATION METHODS AND MEDICINAL USES THEREOF
A kind of tetrahydro isoquinoline derivatives (I), their preparation methods, medicine compositions and medicinal uses thereof, especially their uses as κ-opioid receptor excitant in pain relieving, which belongs to the medicine chemistry. The substituents R1, R2, R3, R4 of general formula (I) are defined as the description.
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Page/Page column 8

(2009/04/23)

Green molecular transformation by a B12-TiO2 hybrid catalyst as an alternative to tributyltin hydride
The B12-TiO2 hybrid catalyst was effectively used for the radical reactions, such as 1,2-migrations of phenyl groups and acyl groups under irradiation by UV light, and the selectivity of the reaction was controlled by the solvent system.
Shimakoshi, Hisashi,Abiru, Makoto,Izumi, Shin-Ichiro,Hisaeda, Yoshio
supporting information; experimental part
p. 6427 - 6429
(2010/03/04)

Highly efficient synthesis of functionalized dihydronaphthalenes, tetrahydronaphthalenes, and tetrahydroisoquinolines by iron-catalyzed intramolecular Friedel-Crafts reaction of aryl-containing propargylic alcohols
An efficient, convenient, and one-pot procedure for the synthesis of a series of new dihydro- and tetrahydronaphthalenes as well as tetrahydroisoquinolines has been established through Lewis acid-catalyzed intramolecular Friedel-Crafts reaction of aryl-substituted propargylic alcohols.
Huang, Wen,Hong, Longcheng,Zheng, Pengzhi,Liu, Ruiting,Zhou, Xigeng
body text
p. 3603 - 3610
(2009/09/06)

Peptide deformylase inhibitors of Mycobacterium tuberculosis: Synthesis, structural investigations, and biological results
Bacterial peptide deformylase (PDF) belongs to a subfamily of metalloproteases catalyzing the removal of the N-terminal formyl group from newly synthesized proteins. We report the synthesis and biological activity of highly potent inhibitors of Mycobacterium tuberculosis (Mtb) PDF enzyme as well as the first X-ray crystal structure of Mtb PDF. Structure-activity relationship and crystallographic data clarified the structural requirements for high enzyme potency and cell based potency. Activities against single and multi-drug-resistant Mtb strains are also reported.
Pichota, Arkadius,Duraiswamy, Jeyaraj,Yin, Zheng,Keller, Thomas H.,Alam, Jenefer,Liung, Sarah,Lee, Gladys,Ding, Mei,Wang, Gang,Chan, Wai Ling,Schreiber, Mark,Ma, Ida,Beer, David,Ngew, Xinyi,Mukherjee, Kakoli,Nanjundappa, Mahesh,Teo, Jeanette W.P.,Thayalan, Pamela,Yap, Amelia,Dick, Thomas,Meng, Wuyi,Xu, Mei,Koehn, James,Pan, Shi-Hao,Clark, Kirk,Xie, Xiaoling,Shoen, Carolyn,Cynamon, Michael
scheme or table
p. 6568 - 6572
(2009/09/30)

Selective reduction of mono- and disubstituted olefins by NaBH4 and catalytic RuCl3
Direct use of the relatively inexpensive reagent, RuCl3 × H2O, as a catalyst for the reductions of olefins in the presence of water is reported. The combination of cheap and readily available sodium borohydride and a catalytic amount of RuCl3 × H2O selectively reduces mono- and disubstituted olefins, whereas trisubstituted olefins, unless activated, and benzyl ethers remain inert.
Sharma, Pawan K.,Kumar, Surender,Kumar, Pawan,Nielsen, Poul
p. 8704 - 8708
(2008/03/14)

Unprecedented reaction between ethyl α-cyanocinnamate and o-phenylenediamine: Development of an efficient method for the transfer hydrogenation of electronically depleted olefins
A reaction between ethyl α-cyanocinnamate and o-phenylenediamine under thermal conditions yielded 2-cyano-3-phenyl-propionic acid ethyl ester, 2-phenyl benzimidazole, and ethyl cyanoacetate. The mechanistic revelations led to the development of a simple and efficient transfer-hydrogenation process from the in situ generated benzimidazolines to activated olefins under solventless and catalyst-free conditions. Georg Thieme Verlag Stuttgart.
Kumar, Satish,Kapoor, Kamal K.
p. 2809 - 2814
(2008/02/13)

Fe-Catalyzed reactions of 2-chloro-1,7-dienes and allylmalonates
Fe(III)(BIAP)Cl3 complex catalyzes alkylative cyclization of 2-chloro-1,7-heptadiene in the presence of triethylaluminum. It also catalyzes deallylation of certain 2-allyl-2-substituted malonates under the same reaction conditions.
Ne?as, David,Drabina, Pavel,Sedlák, Milo?,Kotora, Martin
p. 4539 - 4541
(2008/02/03)