- Catalytic Asymmetric Tandem Reaction of o-Alkynylbenzaldehydes, Amines, and Diazo Compounds
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An efficient asymmetric tandem reaction of o-alkynylbenzaldehydes, amines, and diazo compounds catalyzed by chiral silver imidodiphosphate has been established. Chiral 1,2-dihydroisoquinoline analogues have a tertiary stereocenter at the C1 position, and substituents at the C3 position are available with up to 97% yields and 98% ee. These products can be elaborated into the corresponding β-aminophosphonates or PARP1-inhibitor analogues.
- Wu, Wei,Liao, Na,Wei, Qi,Huang, Jiaying,Huang, Qi,Peng, Yungui
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supporting information
p. 6872 - 6876
(2021/09/14)
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- Tunable Synthesis of Indeno[1,2- c]furans and 3-Benzoylindenones via FeCl3-Catalyzed Carbene/Alkyne Metathesis Reaction of o-Alkynylbenzoyl Diazoacetates
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An efficient synthesis of indeno[1,2-c]furan and 3-benzoylindenone derivatives through a FeCl3-catalyzed carbene/alkyne metathesis reaction of o-alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5-exo-dig carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first example in which FeCl3 is used as a catalyst for a carbene/alkyne metathesis reaction. Finally, derivatization reactions were carried out to showcase the value of the products.
- Li, Bin,Shen, Nana,Yang, Yujie,Zhang, Xinying,Fan, Xuesen
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supporting information
p. 388 - 393
(2021/01/13)
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- Light-Enabled Radical 1,4-Aryl Migration Via a Phospho-Smiles Rearrangement
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Rearrangement reactions in organic chemistry are attractive strategies to build efficiently complex scaffolds, in just one step, from simple starting materials. Among them, aryl migrations are certainly one of the most useful and straightforward rearrangement for building attractive carbon-carbon bonds. Of note, anionic aryl migration reactions have been largely described compared to their radical counterparts. Recently, visible-light catalysis has proven its efficiency to generate such radical rearrangements due to the concomitant loss of a particle (often CO2 or SO2), which is the driving-force of the reaction. Here, we disclose a Smiles-type rearrangement, triggered by a phosphorus-containing unit (arylphosphoramidate), therefore called "phospho-Smiles"rearrangement, allowing a Csp2-Csp2 bond formation thanks to a 1,4-aryl migration reaction. In addition, combining this approach with a radical hydroamination/amination reaction produces an amination/phospho-Smiles cascade particularly attractive, for instance, to investigate the synthesis of the phthalazine core, a scarcely described scaffold of interest for medicinal chemistry projects.
- De Abreu, Maxime,Belmont, Philippe,Brachet, Etienne
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p. 3758 - 3767
(2021/02/01)
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- Facile preparation of 3-aryl-4-iodoisoquinolines from N-(o-Arylethynyl)benzyl p-toluenesulfonamides with iodine and base
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Treatment of N-(o-arylethynyl)benzyl p-toluenesulfonamides with molecular iodine in the presence of NaHCO3 at 60 °C, followed by the reaction with tBuOK at room temperature gave 3-aryl-4-iodoisoquinolines in good yields. 4-Iodo-3-phenylisoquinoline, which is one of the obtained 3-aryl-4-iodoisoquinolines, was further transformed into isoquinoline derivatives smoothly. The present approach is a novel one-pot method for the preparation of 3-aryl-4-iodoisoquinolines from N-(o-arylethynyl)benzyl p-toluenesulfonamides under transition-metal-free conditions.
- Naruto, Hiroki,Togo, Hideo
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- Silver/Rhodium Relay Catalysis Enables C?H Functionalization of In Situ Generated Isoquinolines with Sulfoxonium Ylides: Construction of Hexahydrodibenzo[a,g]quinolizine Scaffolds
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Employing silver/rhodium relay catalysis strategy, an intramolecular electrophilic cyclization and C?H activation followed by cascade hydrogenation and reductive amination has been developed. The acylmethylated isoquinoline derivatives could be afforded with broad substrate scope in 23–88% yields, which could be further transformed to the core skeleton of hexahydrodibenzo[a,g]quinolizine as drug-candidates. Moreover, this reaction was achieved in a gram-scale. A reasonable reaction mechanism has been proposed based on a series of control and KIE experiments. (Figure presented.).
- Li, Quanzhe,Liu, Ruixing,Wei, Yin,Shi, Min
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supporting information
p. 2664 - 2669
(2021/04/05)
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- Synthesis of N-(isoquinolin-1-yl)sulfonamides via Ag2O-catalyzed tandem reaction of ortho-alkynylbenzaldoximes with benchtop stabilized ketenimines
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In this project, a moderately efficient approach to multisubstituted N-(isoquinolin-1-yl)sulfonamide derivatives was illustrated, utilizing ortho-alkynylbenzaldoximes and zwitterionic ketenimine salts in a tandem reaction catalyzed by silver oxide. The oxophilicity of Ag2O, along with its nature as Lewis acid, pave the way for a smooth [3 + 2] cycloaddition between isoquinoline N-oxides and ketenimine species, which is a key step in this reaction. DFT calculation suggests that 1,3-dipolar cycloaddition of nitrone and ketenimine proceeds through a selective stepwise mechanism.
- Hayatgheybi, Sepideh,Khosravi, Hormoz,Zahedian Tejeneki, Hossein,Rominger, Frank,Bijanzadeh, Hamid Reza,Balalaie, Saeed
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supporting information
p. 3524 - 3529
(2021/05/10)
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- Radical Cascade Bicyclization/Aromatization of 1,7-Enynes with 1,3-Dicarbonyl Compounds towards 2,3-Dihydro-1H-cyclopenta[a]naphthalenes
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An Ag-catalyzed radical cascade bicyclization/aromatization of C-linked 1,7-enynes with 1,3-dicarbonyls has been achieved, providing a step- and atom-economy approach for the construction of 2,3-dihydro-1H-cyclopenta[a]naphthalenes, an important structural scaffold existed in biologically active compounds. From this transformation, structurally diverse 2,3-dihydro-1H-cyclopenta[a]naphthalenes were obtained in moderate to good yields with high regioselectivity. Moreover, the further product derivatizations were also exemplified. (Figure presented.).
- Cai, Tao,Chen, Jianhui,Chen, Xinyu,Gao, Yuzhen,Li, Peiqin,Ni, Yuqi,Shen, Runpu,Sun, Tao,Wu, Chunlei,Xu, Huiting,Xu, Yanfei,Zhang, Zhebing
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supporting information
p. 3750 - 3755
(2021/07/09)
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- One-pot Synthesis of Isoquinoline-Fused Isoquinolines via Intramolecular Hydroamination/Aza-Claisen Type Rearrangement Cascade
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A one-pot, two-step synthesis of isoquinoline-fused isoquinolines from α-amino acid esters and 2-alkynyl benzaldehydes are reported. The strategy comprises an unconventional Pictet-Spengler reaction between α-amino acid esters and 2-alkynyl benzaldehydes to give isoquinoline intermediates. Subsequent gold-catalyzed intramolecular hydroamination furnishes isoquinoline-fused isoquinolines. The scope of this strategy is further extended to prepare multisubstituted isoquinoline-fused isoquinolines via subjecting the N-allylated isoquinoline intermediates to gold-catalyzed intramolecular hydroamination followed by aza-Claisen type rearrangement. (Figure presented.).
- Chiu, Wei-Jung,Chen, Jin-Yu,Liu, Shih-I,Barve, Indrajeet J.,Huang, Wan-Wen,Sun, Chung-Ming
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p. 2834 - 2842
(2021/04/26)
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- Modular synthesis of 3-substituted isocoumarinsviasilver-catalyzed aerobic oxidation/6-endoheterocyclization ofortho-alkynylbenzaldehydes
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A method involving silver-catalyzed aerobic oxidation/6-endoheterocyclization ofortho-alkynylbenzaldehydes to yield 3-substituted isocoumarins is described. The developed protocol allows convenient access to a range of synthetically useful 3-substituted isocoumarins and related fused heterocyclolactones in good to high yields, using silver tetrafluoroborate as the catalyst, and atmospheric oxygen as the terminal oxidant and the source of endocyclic oxygen. Mechanistic studies suggest the involvement of a free-radical pathway.
- Wu, Hao,Wang, Yi-Chun,Shatskiy, Andrey,Li, Qiu-Yan,Liu, Jian-Quan,K?rk?s, Markus D.,Wang, Xiang-Shan
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p. 6657 - 6664
(2021/08/16)
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- Catalytic asymmetric three-component reaction of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate
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An efficient enantioselective synthesis of cyclic α-aminophosphonates via multicomponent reactions of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate has been developed with the use of a chiral silver spirocyclic phosphate as the catalyst. This protocol provides straightforward access to a series of chiral C1-phosphonylated 1,2-dihydroisoquinoline derivatives with high yields (up to 99%) and high enantioselectivities (up to 94% ee) for a broad substrate scope. The products could be further transformed into densely functionalized compounds and corresponding α-aminophosphonic acids.
- Zou, Liangliang,Huang, Jiaying,Liao, Na,Liu, Yan,Guo, Qixiang,Peng, Yungui
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supporting information
p. 6932 - 6937
(2020/09/15)
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- In situ air oxidation and photophysical studies of isoquinoline-fused N-heteroacenes
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An efficient, metal free and environment friendly synthesis of isoquinoline-fused benzimidazole has been developed via in situ air oxidation. Also, syntheses of isoquinoline-fused quinazolinone heteroacenes were successfully achieved. The synthesized isoquinoline-fused benzimidazole and isoquinoline-fused quinazolinone derivatives showed λmax, Fmax and Φf values in the ranges 356-394 nm, 403-444 nm and 0.063-0.471, respectively, in CHCl3,.
- Koketsu, Mamoru,Ninomiya, Masayuki,Sonawane, Amol D.,Sonawane, Rohini A.,Win, Khin Myat Noe
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p. 2129 - 2138
(2020/03/27)
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- Polarization Effect on Regioselectivity of Pd-Catalyzed Cyclization of 2-Alkynylbenzaldehydes
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We report a study on the relationship between the polarization of C≡C bond in a series of 2-alkynylbenzaldehydes and the regioselectivity of their Pd-catalyzed annulation reactions. The electrophilic and nucleophilic character of the triple bond carbon atoms was examined using 13C and HMBC NMR experiments. The direction of polarization is determined only by the formyl group and its position on an aromatic ring. On the other hand, the strength of the polarization expressed through chemical shift difference Δδ of acetylenic carbon atoms is a result of electron-withdrawing or electron-donating ability of the other substituent. Out of two possible regioisomers, the Pd-catalyzed cyclization reactions of 2-alkynylbenzaldehydes that were studied predominantly afforded 1H-isochromenes suggesting that the polarization of a triple bond is one of the contributing factors in the regioselectivity of this process.
- Nardangeli, Nolan,Topolov?an, Nikola,Simionescu, Razvan,Hudlicky, Tomá?
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supporting information
p. 227 - 233
(2019/11/29)
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- Gold-Catalyzed Cyclization of 2-Alkynylaldehyde Cyclic Acetals via Hydride Shift for the Synthesis of Indenone Derivatives
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An efficient gold-catalyzed cyclization of 2-alkynylaldehyde cyclic acetals has been developed for the synthesis of indenone derivatives. A wide variety of functionalized indenone derivatives can be obtained in good-to-excellent yields. HMBC and NOESY NMR analyses and mechanistic elucidation experiments revealed that the cyclization occurs via a 1,5-H shift. The cyclic acetal group promoted the 1,5-H shift by activating the benzylic C-H bond and preventing the migration of the alkoxy group by tethering both alkoxy groups.
- Yamada, Tsuyoshi,Park, Kwihwan,Tachikawa, Takumu,Fujii, Akiko,Rudolph, Matthias,Hashmi, A. Stephen K.,Sajiki, Hironao
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supporting information
p. 1883 - 1888
(2020/03/03)
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- Transition-Metal-Free Reverse Reactivity of (2-Alkynyl)-Arylaldimines: Assembly of Functionalized Amino-Indinones
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Transition-metal-free regioselective synthesis of functionalized amino-indenones by the reaction of ortho-alkynylaldehydes with a broad range of primary amines by intramolecular cyclization has been described. The designed reaction proceeds through KOH-mediated Prins-type cyclization and DMSO-promoted oxidation of the cyclopent-2-en-1-one system. The proposed mechanism and role of solvent were well supported by control experiments. For the first time, we have disclosed the reverse reactivity of (2-alkynyl)-arylaldimines in a super basic system.
- Saini, Kapil Mohan,Saunthwal, Rakesh K.,Sushmita,Verma, Akhilesh K.
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supporting information
p. 1017 - 1021
(2020/01/25)
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- Regio- and stereoselective intramolecular hydroalkoxylation of aromatic alkynols: an access to dihydroisobenzofurans under transition-metal-free conditions
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An efficient, transition-metal-free method to synthesize dihydroisobenzofuran derivatives via intramolecular hydroalkoxylation of aromatic alkynols with the promotion of cesium carbonate has been developed. The reaction proceeds regioselectively with exclusive formation of 5-exo-dig product, and only Z-isomer of the new generated double bond is observed. This new protocol features with milder reaction conditions, more convenient operation and satisfactory selectivities.
- Yu, Shu-Yan,Gao, Li-Hong,Wu, Jing-Xin,Lan, Hong-Bing,Ma, Yi,Yin, Zhi-Gang
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p. 3303 - 3310
(2020/04/27)
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- Carbonyl-Directed Addition of N-Alkylhydroxylamines to Unactivated Alkynes: Regio- and Stereoselective Synthesis of Ketonitrones
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A variety of ketonitrones were synthesized in moderate to excellent yields with high chemo-, regio-, and stereoselectivity by using carbonyl-directed addition of N-alkylhydroxylamines to unactivated alkynes under mild conditions. The product diverisity could be controlled by the use of different bases, and EtN(n-Pr)2 could promote the formation of ketonitrones while using EtONa as base led to indanone-derived nitrones. Control experiments indicated that the carbonyl group of the substrate acted as an H-bond acceptor except for an electron-withdrawing group, and conjugated enone skeleton accounted for the high selectivity.
- Liu, Yilin,Feng, Xiangqing,Liu, Yanyun,Lin, Hongwei,Li, Yuanxiang,Gong, Yingying,Cao, Lei,Chen, Liping
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supporting information
p. 382 - 386
(2019/01/11)
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- Stereospecific Synthesis of (Z,Z)-Isobenzofurans via Radical-Enabled Cleavage of C(sp3)?C(sp3) and C(sp2)-Halogen Bonds
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A novel radical-induced annulation/1,8-halosulfonylation of β-alkynyl ketones with haloaryl diazonium tetrafluoroborates and DABCO.bis(sulfur dioxide) was first achieved via the cleavage/recombination of C(sp3)?C(sp3) and C(sp2)-halogen bonds, from which 47 examples of sulfone-containing 1,3-dimethylene-substituted (Z,Z)-isobenzofurans as single stereoisomers were synthesized in generally good yields. This multicomponent pathway is proposed to proceed through the in-situ generation of arylsulfonyl radicals, followed by selective radical addition-cyclization and ring-opening of the cyclopropyl unit as well as C(sp2)-halogen bond cleavage, resulting in the consecutive construction of three new chemical bonds, including C?S, C?O and C-halogen bonds. (Figure presented.).
- Huang, Min-Hua,Shi, Hao-Nan,Zhu, Chi-Fan,He, Chun-Lan,Hao, Wen-Juan,Tu, Shu-Jiang,Jiang, Bo
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supporting information
p. 5340 - 5345
(2019/11/14)
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- Hydrophilic Pd-phosphines catalyzed one-pot synthesis of substituted isoquinolines, furopyridines and thienopyridines in aqueous medium
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A first example of simple and efficient hydrophilic Pd-phosphine complexes catalyzed one-pot three-component reaction of ortho-bromo aldehydes, terminal alkynes and ammonium acetate proceeds through the tandem coupling-imination-annulation path for the synthesis of substituted isoquinolines, furopyridines and thienopyridines in good to excellent yields in green aqueous medium at mild temperature was described.
- Guguloth, Veeranna,Thirukovela, Narasimha Swamy,Balaboina, Ramesh,Paidakula, Suresh,Vadde, Ravinder
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supporting information
p. 297 - 299
(2019/01/04)
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- Synthesis of Functionalized Cyclobutane-Fused Naphthalene Derivatives via Cascade Reactions of Allenynes with tert-Butyl Nitrite
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A novel synthesis of cyclobutanol-fused 2-nitronaphthalen-1-ols and nitrocyclobutane-fused naphthalene-1,2-diones through cascade reactions of benzene-linked allenynes with tert-butyl nitrite is presented. The formation of the title compounds involves a tandem process including allenyne [2+2] cycloaddition, radical addition onto the in situ formed cyclobutenyl moiety followed by radical coupling/oxidation. Interestingly, different kinds of functionalized naphthalene derivatives could be obtained selectively from the same substrates, and the selectivity was easily controlled by finely tuning the reaction conditions. (Figure presented.).
- Feng, Tian,He, Yan,Zhang, Xinying,Fan, Xuesen
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supporting information
(2019/02/07)
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- Completely Stereoselective Synthesis of Sulfonated 1,3-Dihydroisobenzofurans via Radical Multicomponent Reactions
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Two types of new oxidant-free radical multicomponent reactions of β-alkynyl ketones, aryldiazonium salts, and DABCO·(SO2)2 (DABSO) were established, leading to the tunable generation of two class of sulfonated 1,3-dihydroisobenzofurans with moderate to good yields and complete stereoselectivity under the mild conditions. The radical-induced scission/recombination of the C(sp3)-C(sp3) bond enabled direct 1,8-halosulfonylation of β-alkynyl ketones, giving 1,3-dimethylene-substituted (1Z,3Z)-1,3-dihydroisobenzofurans with substituent diversity by p-nitrobenzyl bromide (PNBB) or p-nitrobenzyl chloride (PNBC) as the halo source. Fine-tuning substituents to strong electron-withdrawing ones, such as nitro, cyano, and trifluoromethyl, linked to aryldiazonium tetrafluoroborates allowed a different annulation/1,5-azosulfonylation process to access sulfonated (Z)-1,3-dihydroisobenzofurans with one quaternary carbon-amino functionality.
- Shi, Hao-Nan,Huang, Min-Hua,He, Chun-Lan,Lu, Hai-Ping,Hao, Wen-Juan,Tu, Xing-Chao,Tu, Shu-Jiang,Jiang, Bo
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p. 13686 - 13695
(2019/10/16)
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- A Mild and Regioselective Synthesis of α-Fluoroketones via Gold and Selectfluor Partnership
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An efficient, mild and rapid synthesis of α-fluoroketones has been developed, via a fruitful association between gold and Selectfluor starting from aldehyde-yne and alkynylaryl ketone derivatives. Several functionalized and synthetically highly valuable α-fluoroketones (21 compounds, up to 92%) were isolated in good to excellent yields via a remarkable regioselective oxyfluorination reaction in EtOH/H2O at room temperature. We have shed some light on parts of the mechanism by reacting diphenylacetylene and aldehyde-yne with or without Selectfluor. The reaction most presumably occurs via a sequential gold-catalyzed regioselective hydration followed by the α-fluorination reaction, but the presence of aldehyde moiety is crucial for the reactivity of alkyne function. The fluoroketones were efficiently transformed to 4-fluoroisoquinolines (9 compounds, 82–95%) of high pharmaceutical interest. (Figure presented.).
- Chen, Xi,Martini, Sophie,Michelet, Véronique
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supporting information
p. 3612 - 3618
(2019/07/10)
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- Hypervalent iodine compound containing heterocyclic ring as well as preparation method and application thereof
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The invention discloses a hypervalent iodine compound containing a heterocyclic ring as well as a preparation method and application thereof. A structure of the compound is shown as a formula (I): theformula (I) is shown in the description, wherein R is selected from hydrogen, halogen, alkyl, alkoxy, halogenated alkyl, halogenated alkoxy, nitryl, cyano, hydroxyl or -COOR'; R' is alkyl or halogenated alkyl; and Het is substituted or non-substituted 1,4-benzopyranone, substituted or non-substituted quinolone, substituted or non-substituted isoquinoline, substituted or non-substituted thiobenzopyranone, substituted or non-substituted coumarin and substituted or non-substituted oxepin. The compound disclosed by the invention is novel in structure and is the hypervalent iodine compound containing the heterocyclic ring; the hypervalent iodine compound is stable in structure and simple in preparation method; and meanwhile, the hypervalent iodine compound has a very good inhibition effect onML-1 and MOLM-13 cells and has an extremely great application prospect on prevention and/or treatment effect on leukemia.
- -
-
Paragraph 0158; 0159; 0160
(2019/01/08)
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- Heterocyclic Iodoniums for the Assembly of Oxygen-Bridged Polycyclic Heteroarenes with Water as the Oxygen Source
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A diverse set of novel heterocyclic iodoniums was synthesized for the first time. The reactions of these unique iodoniums with environmentally benign water as the oxygen source provided structurally complex oxygen-incorporated heteropolycycles that are essential motifs in natural products and biologically active compounds. The transformation only required low-cost copper acetate. Further derivatization of the obtained polycycles expanded the structural diversity, which is important in the building of chemical libraries for drug discovery.
- Zhu, Daqian,Wu, Zhouming,Luo, Bingling,Du, Yongliang,Liu, Panpan,Chen, Yunyun,Hu, Yumin,Huang, Peng,Wen, Shijun
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supporting information
p. 4815 - 4818
(2018/08/24)
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- Construction of Six-Membered Silacyclic Skeletons via Platinum-Catalyzed Tandem Hydrosilylation/Cyclization with Dihydrosilanes
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Catalytic silicon-carbon or silicon-heteroatom bond-forming hydrosilylation has become increasingly important in synthetic chemistry, catalysis and organosilicon chemistry. Herein we report a platinum-catalyzed one-pot and tandem hydrosilylation/cyclization of OH-containing alkynes with dihydrosilanes, allowing for facile synthesis of six-membered organosilicon compounds, including silyloxycycles and cyclic siloxanes in high yields and with good stereoselectivities. (Figure presented.).
- Long, Peng-Wei,Bai, Xing-Feng,Ye, Fei,Li, Li,Xu, Zheng,Yang, Ke-Fang,Cui, Yu-Ming,Zheng, Zhan-Jiang,Xu, Li-Wen
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supporting information
p. 2825 - 2830
(2018/08/17)
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- Cobalt-catalyzed regioselective syntheses of indeno[2,1-: C] pyridines from nitriles and diynes bearing propargyl fragments
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A highly efficient CoI2/o-phenanthroline catalyzed cycloaddition reaction of diynes bearing TBS protected propargylic alcohol fragments with nitriles has been developed. This methodology offers regioselective access, with good functional group tolerance, to various indeno[2,1-c]pyridine derivatives in moderate to excellent yields. It was found that o-phenanthroline as a bidentate nitrogen ligand showed high efficacy in this cycloaddition reaction.
- Xu, Murong,Zheng, Zhong,Wang, Mengdan,Kong, Lingkai,Ao, Yujuan,Li, Yanzhong
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supporting information
p. 8761 - 8768
(2018/11/30)
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- Synthesis of selectively 4-substituted 9,9′-spirobifluorenes and modulation of their photophysical properties
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Synthesis of selectively 4-substituted 9,9′-spirobifluorenes was accomplished by using catalytic [2 + 2 + 2]-cyclotrimerization of specifically substituted diynols with alkynes to the corresponding fluorenols. Further synthetic transformations provided the target molecules. The measurement of the photophysical properties of the prepared 4-substituted 9,9′-spirobifluorenes revealed that their emission maxima depended on the electronic properties of the substituents present in the para position: the presence of an electron accepting group strongly favored the maxima red shift toward the blue VIS region (CF3λmax = 361 nm vs. MeO λmax = 330 nm). Adding further substituents (aryl or arylethynyl moieties) on the phenyl ring in position 4 did not lead to a dramatic improvement in the emission maxima (CF3C6H4, λmax = 369 nm, CF3C6H4CC, λmax = 370 nm), but increased their quantum yields considerably. In addition, a series of 9,9′-spirobifluorenes possessing various extended π-systems (pyrene, anthracene, etc.) were synthesized. In general, the emission maxima pattern reflected that of the parent π-systems, but they were red shifted by 10-30 nm. Finally, also a 1-[4-(9,9′-spirobifluorene-4-yl)phenyl]-2-aryl-ortho-carborane was prepared. These data thus may provide guidelines for further design of 9,9′-spirobifluorenes with tailored properties.
- Kaiser, Reinhard P.,Mosinger, Ji?í,Císa?ová, Ivana,Kotora, Martin
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supporting information
p. 6913 - 6920
(2017/09/01)
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- Silver-Catalysed Domino Approach to 1,3-Dicarbo-Substituted Isochromenes
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We report herein the first example of the silver triflate catalysed synthesis of 1,3-dicarbo-substituted isochromene derivatives starting from 2-alkynyl(hetero)arylaldehydes and enolizable ketones. The reaction proceeds in a cascade fashion under mild heating with complete regioselectivity and moderate-to-good yields. In some cases, the reaction gives unexpected homodimeric products. Two competitive mechanistic paths for the formation of the desired isochromene derivatives and the homodimeric products are described.
- Dell'Acqua, Monica,Pirovano, Valentina,Peroni, Stefano,Tseberlidis, Giorgio,Nava, Donatella,Rossi, Elisabetta,Abbiati, Giorgio
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supporting information
p. 1425 - 1433
(2017/04/01)
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- Metal-free benzannulation of 1,7-diynes towards unexpected 1-aroyl-2-naphthaldehydes and their application in fused aza-heterocyclic synthesis
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A novel I2-mediated benzannulation of 1,7-diyne-involved 1,4-oxo-migration was established, providing a range of unexpected 1-aroyl-2-naphthaldehydes with a 1,4-dicarbonyl unit. The resulting 1-aroyl-2-naphthaldehydes were successfully applied in the synthesis of benzo[e]isoindol-3-ones and benzo[e]benzo[4,5]imidazo[2,1-a]isoindoles using aromatic amines and benzene-1,2-diamines as nucleophiles, respectively. The mechanisms for the formation of these compounds were proposed.
- Wang, Ai-Fang,Zhou, Peng,Zhu, Yi-Long,Hao, Wen-Juan,Li, Guigen,Tu, Shu-Jiang,Jiang, Bo
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supporting information
p. 3369 - 3372
(2017/03/22)
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- Highly selective construction of medium-sized lactams by palladium-catalyzed intramolecular hydroaminocarbonylation of aminoalkynes
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A novel palladium-catalyzed intramolecular hydroaminocarbonylation of aminoalkynes has been developed. This direct and operationally simple protocol provides a rapid and reliable approach to a diverse array of valuable seven-and eight-membered lactams with high chemoselectivity and regioselectivity. The high selectivity might be attributed to rational tuning the electronic nature of the amine moiety and the palladium catalyst which enabled this transformation to proceed in the absence of acidic or any other additives under fairly mild reaction conditions. This method paves the way for the synthesis of medium-sized lactams.
- Hu, Yue,Huang, Hanmin
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supporting information
p. 5070 - 5073
(2017/11/07)
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- Copper accelerated one-pot sequential tandem synthesis of tetrahydropurinoisoquinoline derivatives
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Copper catalyzed efficient and operationally simple tandem synthesis of purino[8,9-a]isoquinolinedione from 5,6-diamino-1,3-dimethyluracil and in situ generated alkenyl aldehyde has been described. In this cascade reaction C-C and C-N bonds are formed through Sonogashira coupling, 5-endo cyclization, and 6-endo cyclization in a same reaction vessel.
- Maji, Pradip Kumar,Mahalanobish, Ayan
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p. 1847 - 1855
(2017/10/24)
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- Gold-Catalyzed Ring Expansion of Enyne-Lactone: Generation and Transformation of 2-Oxoninonium
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An efficient gold-catalyzed ring-expansion reaction of enyne-lactones to form 2-oxoninonium intermediates is reported. The 2-oxoninonium generated in this work could undergo further 6π electrocyclization and aromatization reaction to produce different aromatic compounds.
- Luo, Kui,Cao, Tongxiang,Jiang, Huanfeng,Chen, Lianfen,Zhu, Shifa
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supporting information
p. 5856 - 5859
(2017/11/10)
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- Merging [2+2] Cycloaddition with Radical 1,4-Addition: Metal-Free Access to Functionalized Cyclobuta[a]naphthalen-4-ols
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A metal-free [2+2] cycloaddition and 1,4-addition sequence induced by S-centered radicals has been achieved by treating benzene-linked allene-ynes with aryldiazonium tetrafluoroborates and DABCO-bis(sulfur dioxide) in a one-pot procedure. The reaction provides a greener and more practical access to functionalized cyclobuta[a]naphthalen-4-ols with valuable applications. More than 50 examples are demonstrated with excellent diastereoselectivity and chemical yields. The reaction pathway is proposed to proceed by the following steps:[2+2] cycloaddition, insertion of SO2, 1,4-addition, diazotization, and tautomerization.
- Liu, Feng,Wang, Jia-Yin,Zhou, Peng,Li, Guigen,Hao, Wen-Juan,Tu, Shu-Jiang,Jiang, Bo
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supporting information
p. 15570 - 15574
(2017/12/02)
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- Visible-Light-Promoted Generation of α-Ketoradicals from Vinyl-bromides and Molecular Oxygen: Synthesis of Indenones and Dihydroindeno[1,2-c]chromenes
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Ortho-alkynylated α-bromocinnamates can be converted by a visible-light-mediated photocascade reaction with molecular oxygen into either indenones or dihydroindeno[1,2-c]chromenes. The one-step process features key photochemical steps, that is, the initial activation of vinyl bromides through energy transfer to give α-ketoradicals in a reaction with molecular oxygen, followed by α-oxidation of an arene moiety by 6-π electrocyclization, and subsequent hydroxylation by an electron-transfer process from the same photocatalyst leads to the dihydroindeno[1,2-c]chromenes.
- Pagire, Santosh K.,Kreitmeier, Peter,Reiser, Oliver
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supporting information
p. 10928 - 10932
(2017/08/30)
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- Zinc-Catalyzed Tandem Diels–Alder Reactions of Enynals with Alkenes: Generation and Trapping of Cyclic o-Quinodimethanes (o-QDMs)
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A systematic investigation of ZnCl2-catalyzed reactions of enynals with alkenes has been undertaken. Structurally unique propeller-like products could be obtained under mild conditions. Cyclic o-quinodimethanes (o-QDMs) are generated through [4+2] cycloaddition between enynals and alkenes. Both electron-poor and electron-rich dienophiles could be used to trap the active intermediate through [4+2] cycloaddition. But [1,5]-H shift products could also be observed when electron-rich alkenes were used as dienophile. DFT calculations were performed to understand the reaction mechanism. A competition between the [4+2] cycloaddition and [1,5]-H shift was proposed for the transformation of cyclic o-QDMs. The selectivity could be affected by the properties of the substrates. (Figure presented.).
- Zhang, Jiantao,Xiao, Yelin,Chen, Kai,Wu, Wanqing,Jiang, Huanfeng,Zhu, Shifa
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supporting information
p. 2684 - 2691
(2016/09/03)
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- Access toward Fluorenone Derivatives through Solvent-Free Ruthenium Trichloride Mediated [2 + 2 + 2] Cycloadditions
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An efficient and practical route for the preparation of highly substituted fluorenones and analogues via solvent-free ruthenium trichloride mediated [2 + 2 + 2] cycloaddition of α,-diynes and alkynes has been developed. This green chemistry approach involves a solventless and atom-economical catalytic process to generate densely functionalized fluorenones and related derivatives of high synthetic utility.
- Ye, Fei,Haddad, Mansour,Michelet, Véronique,Ratovelomanana-Vidal, Virginie
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supporting information
p. 5612 - 5615
(2016/11/17)
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- Gold-Catalyzed Reaction of ortho-Alkynylarylaldehydes with Conjugated Dienes: An Efficient Access to Highly Strained Tetracyclic Bridgehead Olefins
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An unprecedented access to strained tetracyclic bridgehead alkenes by reaction of easily accessible ortho-alkynylarylaldehydes with conjugated dienes is described. The process involves a chemo- and stereo-selective, gold-catalyzed, tandem intermolecular [3+2] cycloaddition/Prins-type ring-closing reaction that allows generating structural complexity in a straightforward manner. This approach for the preparation of anti-Bredt compounds is synthetically superior to those previously reported: the procedure is easy to implement, operates under mild experimental conditions, is efficient, and exhibits a good substrate scope.
- Cao, Ziping,Zhu, Hongbo,Meng, Xin,Tian, Laijin,Sun, Xuejun,Chen, Guang,You, Jinmao
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supporting information
p. 9125 - 9129
(2016/07/14)
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- Pyrazoloisoquinoline compound and synthesis method thereof
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The invention discloses a pyrazoleoisoquinoline compound and a synthesis method thereof. The pyrazoleoisoquinoline compound is represented by a formula I, wherein the R1 represents hydrogen, halogen atoms and alkyl or alkoxy or amino, and the R2 represents hydrogen, halogen atoms and alkyl or alkoxy or amino. The target product is synthesized through four-step reaction, the synthesis method is simple and rapid, the target compound is higher in yield, and a necessary foundation is provided for further research on the compound represented by the formula I or related compounds. In addition, the intermediate provided in the synthesis method is simple in structure and easy to obtain and provides convenience for the preparation of the target compound.
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Paragraph 0038; 0039; 0040
(2016/10/07)
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- Efficient Pathway for the Preparation of Aryl(isoquinoline)iodonium(III) Salts and Synthesis of Radiofluorinated Isoquinolines
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Iodonium compounds play a pivotal role in18F-fluorination of radiopharmaceuticals containing non-activated arenes. However, preparation of these species is limited to oxidation conditions or exchange with organometallics that are prepared from aryl halides. Herein we describe a novel “one-pot” process to assemble aryl(isoquinoline)iodonium salts in 40–94 % yields from mesoionic carbene silver complex and Aryl-I-Py2(OTf)2. The method is general, practical, and compatible with well-functionalized molecules as well as useful for the preparation of a wide range of18F-labeled isoquinolines resulting in up to 92 % radiochemical conversion. As proof of concept, a fluorinated isoquinoline alkaloid,18F-aspergillitine is prepared in 10 % isolated radiochemical yield from the corresponding phenyl(aspergillitine)iodonium salt.
- Yuan, Zheliang,Cheng, Ran,Chen, Pinhong,Liu, Guosheng,Liang, Steven H.
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supporting information
p. 11882 - 11886
(2016/11/17)
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- Silver comes into play: Henry reaction and domino cycloisomerisation sequence catalysed by [Ag(i)(Pc-L)] complexes
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We report herein the synthesis of new pyridine-containing macrocyclic ligands (Pc-L) bearing a non-innocent pendant arm, by exploiting both chiral and functional properties of natural amino acids. The obtained macrocyclic ligands were employed to synthesize well-defined cationic silver(i) complexes that were shown to be competent catalysts for the Henry (nitroaldol) reaction. Good to excellent yields and full selectivity in the β-nitroalcohol product were obtained starting from electron-poor aromatic aldehydes or other activated aldehydes such as furfural under mild reaction conditions. The straightforward synthesis of the macrocyclic ligands starting from cheap commercially available starting materials allowed the introduction of a suitable basic functionality into the ligand pendant arm, thus providing a bifunctional catalyst. Based on our previous experience in the [Ag(i)(Pc-L)] catalysed domino addition/cycloisomerisation reaction of o-alkynylbenzaldehydes and nucleophiles, the synthesis of isochromenes coupling the Henry reaction and the cycloisomerisation in a single step was subsequently explored. Although with low selectivity, [Ag(i)(Pc-L)] cationic complexes were able to promote such a cascade reaction and a possible mechanism based on experimental evidence has been proposed.
- Tseberlidis, Giorgio,Dell'Acqua, Monica,Valcarenghi, Daniele,Gallo, Emma,Rossi, Elisabetta,Abbiati, Giorgio,Caselli, Alessandro
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p. 97404 - 97419
(2016/10/25)
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- Radical Cascade Cyclization: Reaction of 1,6-Enynes with Aryl Radicals by Electron Catalysis
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The radical cascade cyclization of various 1,6-enynes with aryl radicals by electron catalysis under metal-free reaction conditions was explored. Readily available anilines were used as radical precursors, and the reactions proceeded in the absence of any transition metal. These cascades comprise three C–C bond formations, which provide polycyclic structures with extended π-systems. The photophysical properties of some of these novel compounds were investigated, and a plausible reaction mechanism is proposed.
- Xuan, Jun,Gonzalez-Abradelo, Dario,Strassert, Cristian Alejandro,Daniliuc, Constantin-Gabriel,Studer, Armido
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supporting information
p. 4961 - 4964
(2016/10/26)
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- Insights into the Gold-Catalyzed Propargyl Ester Rearrangement/Tandem Cyclization Sequence: Radical versus Gold Catalysis - Myers-Saito- versus Schmittel-Type Cyclization
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A detailed study of the gold-catalyzed tandem 1,3-carboxy migration/allene-enyne cycloisomerization was undertaken. It was found that after the initial allene formation the selectivity of the reaction is strongly influenced by the polarization of the remaining alkyne. Depending on the substitution pattern of the starting diynes, either a Schmittel- or a Myers-Saito-type cyclization was triggered. The 6-endo-dig Myers-Saito-type cyclization gave access to benzo[b]fluorenes, while the Schmittel pathway (5-exo-dig) delivered benzofulvenes as final products. In special cases a yet unknown pathway was opened by the ambiphilic nature of the allene moiety. In these cases completely different products were obtained by the nucleophilic attack of the alkyne moiety onto the allene that can also act as an electrophile. Mechanistic studies revealed that diradical pathways can be ruled out for this type of tandem cyclization reactions and it is shown that both steps of the reaction cascade are catalyzed by the gold complex.
- Rettenmeier, Eva,Hansmann, Max M.,Ahrens, Alexander,Rübenacker, Katharina,Saboo, Tapish,Massholder, Joy,Meier, Christian,Rudolph, Matthias,Rominger, Frank,Hashmi, A. Stephen K.
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supporting information
p. 14401 - 14409
(2015/10/05)
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- Br?nsted Acid-Promoted One-Pot Synthesis of Chrysene Derivatives via Isochromenylium Intermediate Formed in Situ
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Trifluoromethanesulfonic acid (HOTf) promoted cross-coupling of ortho-[2-(4-methoxylphenyl)-alkynyl]acetophenones with ortho-alkynylbenzaldehydes affording chrysene derivatives has been developed. The present cascade reaction provides a facile one-pot synthesis of multisubstituted chrysenes as well as naked chrysene under mild conditions. The mechanism experimental results demonstrate isochromenylium is a key intermediate for this transformation.
- Guo, Biao,Zhou, Yiming,Zhang, Lei,Hua, Ruimao
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p. 7635 - 7641
(2015/08/18)
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- Expedient Iodocyclization Approach Toward Polysubstituted 3H-Benzo[e]indoles
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A facile and expedient iodocyclization of 4-(2-prop-1-ynylphenyl)-1H-pyrroles towards the synthesis of polysubstituted 3H-benzo[e]indoles is reported. The transformation was optimized and the best results were obtained by using iodine (1.2 equiv,) in dichloromethane, and potassium carbonate as base. The starting 1,2,3,4-tetrasubstituted pyrroles were efficiently obtained by means of a nickel(II) chloride-promoted four-component (nitromethane, amine, 2-alkynylbenzaldehyde and ethyl acetoacetate) reaction. Further functionalization of the resulting 5-iodoheterocycles was also explored.
- Martins, Guilherme M.,Zeni, Gilson,Back, Davi F.,Kaufman, Teodoro S.,Silveira, Claudio C.
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supporting information
p. 3255 - 3261
(2015/11/03)
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- Mechanistic insight into transition metal-catalyzed reaction of enynal/enynone with alkenes: Metal-dependent reaction pathway
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A systematic study of the transition metal-catalyzed reaction of enynal/enynone with alkenes has been reported. It was found that the reaction has two metal-dependent reaction pathways. One led to the formation of 1,2-DHN, while another led to cyclic-o-QDM.
- Zhu, Shifa,Huang, Hua,Zhang, Zhicai,Ma, Tongmei,Jiang, Huanfeng
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p. 6113 - 6122
(2014/07/21)
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- Silver-catalyzed domino hydroarylation/cycloisomerization reactions of ortho-alkynylbenzaldehydes: An entry to functionalized isochromene derivatives
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A Ag-catalyzed versatile and efficient access to 1H,1-arylisochromenes is reported. Starting from ortho-alkynylbenzaldehydes bearing various substitution patterns on the benzaldehyde and alkynyl units, the use of silver triflate (10 mol %) allowed a domino hydroarylation/cycloisomerization reaction process, leading to aryl-functionalized 1H-isochromene (>10 compounds, 80-98% yields). Notably, the reaction conditions were also compatible with benzaldehydes bearing an aliphatic-substituted alkynyl moiety with modest to good yields (34-88%, 10 compounds).
- Mariaule, Galle,Newsome, Gregory,Toullec, Patrick Y.,Belmont, Philippe,Michelet, Vronique
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supporting information
p. 4570 - 4573
(2015/02/19)
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- Rapid access to novel 1,2,3-triazolo-heterocyclic scaffolds via tandem knoevenagel condensation/azide-alkyne 1,3-dipolar cycloaddition reaction in one pot
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An operationally simple, one-pot, two-step cascade method has been developed to afford biologically important fused 1,2,3-triazolo-heterocyclic scaffolds from 2-alkynyl aryl(heteroaryl) aldehydes and phenacyl azides. This unique atom economical transformation engages four reactive centers (aldehyde, alkyne, active methylene, and azide) under metal-free catalysis.
- Maurya, Ram Awatar,Adiyala, Praveen Reddy,Chandrasekhar,Reddy, Chada Narsimha,Kapure, Jeevak Sopanrao,Kamal, Ahmed
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p. 466 - 477
(2014/12/10)
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- Bioinspired intramolecular diels-alder reaction: A rapid access to the highly-strained cyclopropane-fused polycyclic skeleton
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A bioinsipred gold-catalyzed tandem Diels-Alder/Diels-Alder reaction of an enynal and a 1,3-diene, forming the highly-strained benzotricyclo[3.2.1.0 2,7]octane skeleton, was reported. In contrast, a Diels-Alder/Friedel-Crafts tandem reaction occurred instead when silver salts were used as the catalyst. Although both reactions experienced the similar Diels-Alder reaction of a pyrylium intermediate with a 1,3-diene, they have different reaction mechanisms. The former proceeded with a stepwise Diels-Alder reaction, while the latter one with a concerted one. Mother nature knows best! A gold-catalyzed reaction of enynals and 1,3-dienes, giving rapid access to the highly strained benzotricyclo[3.2.1.02,7]octane skeleton, is reported (see scheme; QMD=quinodimethane). Owing to the mild reaction conditions, excellent substrate scope, and high functional-group tolerance, this system holds potential for the construction of complex molecules with the tricyclo[3.2.1.02,7]octane skeleton. Copyright
- Zhu, Shifa,Guo, Zhengjiang,Huang, Zhipeng,Jiang, Huanfeng
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supporting information
p. 2425 - 2430
(2014/03/21)
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- Mild regiospecific synthesis of 1-alkoxy-isochromenes catalyzed by well-defined [silver(I)(pyridine-containing ligand)] complexes
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The synthesis of 3-substituted-1-alkoxyisochromenes starting from 2-alkynylbenzaldehydes and different alcohols is reported. The reaction is catalyzed by a silver(I) complex with an original macrocyclic pyridine-containing ligand. The approach is characterized by absolute regioselectivity, mild reaction conditions, good to excellent reaction yields, cleanness of the reaction, and reduced purification steps. The reaction mechanism was investigated by in-depth 1H NMR experiments and an aimed trapping experiment.
- Dellacqua, Monica,Castano, Brunilde,Cecchini, Clara,Pedrazzini, Tommaso,Pirovano, Valentina,Rossi, Elisabetta,Caselli, Alessandro,Abbiati, Giorgio
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p. 3494 - 3505
(2014/05/06)
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- Fluoro-ene reaction versus [2+2] cycloaddition in the thermal C 2-C6 cyclization of enyne-allenes: An experimental and theoretical investigation
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A series of fluoroalkyl-substituted enyne-allenes have been synthesized by a new route with the aim of elucidating the possibility of a fluoro-ene reaction via an intermediate fulvenyl diradical generated in the thermal C 2-C6 (Schmittel) cyclization reaction. As a result of the strong C-F bond, fluorine atom transfer was not observed. Instead, 1H-cyclobuta[a]indenes were formed in good yields despite the high strain energy. DFT calculations at the B3LYP level of theory indicated that although the fluoro-ene reaction is the most exothermic reaction available, cyclobutene formation is kinetically favored over the [1,5]-fluorine shift by 5-15 kcal mol-1 in various model compounds. Copyright
- Cinar, M. Emin,Vavilala, Chandrasekhar,Jaquet, Ralph,Bats, Jan W.,Schmittel, Michael
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p. 5166 - 5177
(2014/10/15)
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- Facile synthesis of halogenated spiroketals via a tandem iodocyclization
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A strategy for the synthesis of spiroketal compounds through a tandem iodocyclization of 1-(2-ethynylphenyl)-4-hydroxybut-2-yn-1-one derivatives is presented. This reaction could proceed under very mild conditions in a short time and avoid the use of expensive and toxic metal catalysts. Moreover, the resulting halides can be further exploited by subsequent palladium-catalyzed coupling reactions, which act as the important intermediates for building other valuable compounds.
- Wang, Jia,Zhu, Hai-Tao,Li, Ying-Xiu,Wang, Li-Jing,Qiu, Yi-Feng,Qiu, Zi-Hang,Zhong, Mei-Jin,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 2236 - 2239
(2014/05/06)
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