نتایج جستجو برای: stereoselectivity

تعداد نتایج: 1551  

Journal: :Organic & biomolecular chemistry 2012
Lihua Yang Peizhong Xie Erqing Li Xin Li You Huang Ruyu Chen

A novel phosphine-catalyzed intermolecular [3 + 2] cycloaddition of ynones and N-substituted isatins was developed. In this reaction, substituted ynones, serving as a C(3) synthon, were successfully applied in intermolecular annulation reactions. A number of functionalized spirooxazolines were obtained in high yields and stereoselectivity.

Journal: :Organic & biomolecular chemistry 2014
Wang Zhou Youqing Yang Zhiwei Wang Guo-Jun Deng

A rhodium-catalyzed intermolecular hydroarylation of internal alkynes with N-1-phenylbenzotriazoles via C-H bond activation is described. This transformation offers an alternative method for the hydroarylation of internal alkynes with high stereoselectivity. The reaction mechanism was discussed according to the deuterium-labeling experiments.

Journal: :Chemical communications 2013
Philip Andrews Christopher M Latham Marc Magre Darren Willcox Simon Woodward

Stabilized AlHCl(2)·(THF)(2) hydroaluminates RC≡CH with exceptional chemo-, regio- and stereoselectivity under efficient ZrCl(2)(η-C(5)Me(5))(2) catalysis (2-5 mol%). The resulting vinyl alanes undergo palladium cross-coupling with a wide range of sp(2) electrophiles (aryl, heteroaryl and vinyl halides/pseudohalides) in good to excellent yields.

Journal: :Chemical communications 2007
Regina Kratzer Bernd Nidetzky

Wild-type Candida tenuis xylose reductase and two Trp-23 mutants thereof catalyze NADH-dependent reduction of a homologous series of aromatic alpha-keto esters with absolute pseudo re-face stereoselectivity and broad tolerance for the substituent on the aromatic ring, producing the corresponding R-alcohols in high yield.

Journal: :Molecules 2017
Sunhwa Park Jiyun Lee Kye Jung Shin Euichaul Oh Jae Hong Seo

Based on consecutive one-pot conditions combining three palladium-catalyzed reactions (Sonogashira, Heck and Suzuki-Miyaura reactions), a more efficient domino multicomponent method has been successfully developed to access a wide variety of 3-(diarylmethylene)oxindoles. Microwave irradiation and use of a silver salt were the most important factors to achieve high yields and stereoselectivity.

Journal: :Organic letters 2010
Sadananda Ranjit Zhongyu Duan Pengfei Zhang Xiaogang Liu

A novel method for the synthesis of vinyl sulfides by the decarboxylative cross-coupling of arylpropiolic acids with thiols using copper(I) salts as catalysts has been developed. In the presence of CuI and Cs(2)CO(3), a variety of thiols reacted with arylpropiolic acids to afford the corresponding vinyl sulfides in good to excellent yields with high stereoselectivity for Z-isomers.

2014
Carole F Despiau Andrew P Dominey David C Harrowven Bruno Linclau

A total synthesis of paroxetine is reported, with a diastereoselective and diastereoconvergent cobalt-catalysed sp3-sp2 coupling reaction involving a 3-substituted 4-bromo-N-Boc-piperidine (Boc = tert-butoxycarbonyl) substrate as a key step. A 9:1 diastereoselectivity was obtained, while a control experiment involving a conformationally locked 3-substituted 4-bromo-tert-butyl cyclohexane ring p...

Journal: :Organic & biomolecular chemistry 2011
Rodolfo Tello-Aburto Kyle A Kalstabakken Kelly A Volp Andrew M Harned

The cyclization of 2,5-cyclohexadienones tethered to activated methylene groups was studied. The substitution around the cyclohexadienone ring serves to regioselectively direct these cyclizations based primarily on electronic effects. In the case of brominated substrates, these reactions proceed to give highly unusual electron-deficient tricyclic cyclopropanes. By using a Cinchona alkaloid-base...

2014
Eduardo Gómez-Torres Diego A. Alonso Enrique Gómez-Bengoa Carmen Nájera

A wide variety of chiral succinimides have been prepared in high yields and enantioselectivities by an asymmetric conjugate addition of 1,3-dicarbonyl compounds to maleimides under very mild reaction conditions using the bifunctional benzimidazole-derived organocatalyst 5f. Computational and NMR studies support the hydrogen-bonding activation role of the catalyst and the origin of the stereosel...

Journal: :Chemical communications 2011
De-Jun Dong Yuan Li Jie-Qi Wang Shi-Kai Tian

A broad range of readily accessible N-sulfonyl imines undergo olefination reaction with nonstabilized phosphonium ylides under mild conditions to afford an array of both Z- and E-isomers of 1,2-disubstituted alkenes, allylic alcohols, and allylic amines in good yields and with greater than 99 : 1 stereoselectivity.

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