Asymmetric Organocatalytic Sequential Reaction of Structurally Complex Cyclic Hemiacetals and Functionalized Nitro-olefins To Synthesize Diverse Heterocycles
作者:Jun-Ping Pei、Ying-Han Chen、Yan-Kai Liu
DOI:10.1021/acs.orglett.8b01386
日期:2018.6.15
Structurally complex cyclic hemiacetals bearing a racemic tetrasubstituted stereocenter have been prepared in a concise manner and were successfully used in an organocatalytic enantioselective sequence to react with functionalized nitro-olefins, providing bicyclic acetal-containing compounds as two separable epimers with excellent stereoselectivity. The reaction showed broad substrate scope, with respect
A series of α-substituted nitroolefins were employed in organocatalytic asymmetric Michael reactions with aldehydes. γ-Nitro carbonyl products were achieved in good yields (up to 86%) with good stereoselectivities (up to 96% ee and 24â:â1 dr). Reduction of the nitro group followed by intramolecular reductive amination successfully afforded various novel optically active 2,4-disubstituted pyrrolidine compounds.
[EN] PROCESS FOR PREPARATION OF OPTICALLY ACTIVE 1-ERYTHRO-2-AMINO-1-PHENYL-1-PROPANOL<br/>[FR] PROCEDE POUR PREPARER DU 1-ERYTHRO-2-AMINO-1-PHENYL-1-PROPANOL ACTIF DE MANIERE OPTIQUE
申请人:EMMELLEN BIOTECH PHARMACEUTICA
公开号:WO2005100299A1
公开(公告)日:2005-10-27
An efficient cost-effective process for preparation of l-erythro-2-amino-1-phenyl-1-propanol from l-1-phenyl-1-hydroxy-2-propanone, which comprises converting l-1-phenyl-1-hydroxy-2-propanone to l-1-phenyl-1-hydroxy-2-propanone oxime and reducing the oxime with a catalyst consisting of finely divided nickel and aluminium metals giving good diastereomeric purity and yield.
Hydrogen-Bond-Assisted Sequential Reaction of Silyl Glyoxylates: Stereoselective Synthesis of Silyl Enol Ethers
作者:Chen Zhu、Man-Yi Han、Xiu-Xia Liang、Bin Guan、Pinhua Li、Lei Wang
DOI:10.1021/acs.orglett.0c03683
日期:2021.1.1
A novel hydrogen-bond-assisted sequential reaction of silyl glyoxylates is described. This method provides an efficient strategy for the synthesis of silyl enol ethers with high selectivity. In these transformations, hydrogen bonds from 2-nitroethanol and its derivatives are critical to the stereochemical outcome. Both E- and Z-isomers are achieved via Henry reaction/Brook rearrangement/elimination
描述了一种新型的氢键辅助的乙醛酸甲硅烷基酯的顺序反应。该方法为合成高选择性的甲硅烷基烯醇醚提供了有效的策略。在这些转化中,2-硝基乙醇及其衍生物的氢键对于立体化学结果至关重要。既ë -和ž 1: -异构体通过Henry反应/重排布鲁克/消除和亨利反应/重排布鲁克/复古亨利反应/消除过程,分别为(最多99实现Ž -选择性,和9.2:1 È -选择性)。
A Recyclable Organocascade Reaction System: Stereoselective Precipitation of Optically Active cis-δ-Lactols with Quaternary Stereocenters during the Michael-Hemiacetalization Reaction
作者:Fanglin Zhang、Mohui Wei、Junfang Dong、Yirong Zhou、Dengfu Lu、Yuefa Gong、Xiangliang Yang
DOI:10.1002/adsc.201000553
日期:2010.11.22
A cascade Michael–hemiacetalization reaction between β-substituted β-nitroethanols and α,β-unsaturated aldehydes is described, which provides a convenient and efficient synthesis for cis-δ-lactols with quaternarystereocenters in moderate yields with excellent enantioselectivity. Based on the selective precipitation of cis-δ-lactols, which were isolated by filtration, the catalytic system in the filtrate