Sulfoxide-mediated diastereoselective Michael additions. New enantioselective synthesis of C-4 substituted 2-pyroaminoadipic acids
摘要:
Diastereoselective reactions of suitably functionalized homochiral beta-iminosulfoxides with Michael accepters provide a new and efficient route for the asymmetric synthesis of C-4 substituted 2-pyroaminoadipates. Extension of the scope of the sulfoxide-mediated aza-enolate conjugate addition (Hua's reaction) has also been explored. (C) 1999 Elsevier Science Ltd. All rights reserved.
Sulfoxide-mediated diastereoselective Michael additions. New enantioselective synthesis of C-4 substituted 2-pyroaminoadipic acids
摘要:
Diastereoselective reactions of suitably functionalized homochiral beta-iminosulfoxides with Michael accepters provide a new and efficient route for the asymmetric synthesis of C-4 substituted 2-pyroaminoadipates. Extension of the scope of the sulfoxide-mediated aza-enolate conjugate addition (Hua's reaction) has also been explored. (C) 1999 Elsevier Science Ltd. All rights reserved.
Enantioselective synthesis of (+)-(2S,4S,6S)-1-ethoxycarbonyl-6-hydroxymethyl-4-methylpipecolate
作者:Hassan Acherki、Carlos Alvarez-Ibarra、Susana Guzmán-Fernández、Marı́a L. Quiroga-Feijóo
DOI:10.1016/j.tetasy.2003.11.035
日期:2004.2
The enantioselectivesynthesis of (+)-(2S,4S,6S)-1-ethoxycarbonyl-6-hydroxymethyl-4-methylpipecolamide 16 is described. The absoluteconfiguration of stereocenters introduced in (+)-16 was assigned on the basis of 1H NMR data. The results extend the chirality transfer with complete control of stereoselectivity from the sulfinyl group to the 4-position and, hence, to the 6- and 2-positions of the piperidine
描述了(+)-(2 S,4 S,6 S)-1-乙氧基羰基-6-羟甲基-4-甲基哌酰胺16的对映选择性合成。根据1 H NMR数据确定(+)- 16中引入的立体中心的绝对构型。结果通过不对称诱导完全控制了立体选择性,从亚硫酰基到哌啶环的4位,进而到6位和2位,扩展了手性转移。
Diastereoselective synthesis of 4-substituted 5-(p-tolylsulfinyl)-5,6-dehydropiperidin-2-ones. A new approach to methyl l-(2S,4S)-4-methyl-6-oxopipecolate
作者:Hassan Acherki、Carlos Alvarez-Ibarra、Alfonso de Dios、Marta Gutiérrez、Marı́a L. Quiroga
DOI:10.1016/s0957-4166(01)00553-5
日期:2001.12
The sulfoxide-mediated diastereoselective Michael reaction of homochiral alpha-sulfinylketimines 1a-d and beta-substituted ene esters 2a-d (Hua's reaction) was explored. Straight forward cyclization of the open-chain adducts take place under the reaction conditions to provide the 4-substituted 5-(p-tolylsulfinyl)-5,6-dehydropiperidin-2-ones 3 and 7-12, whose stereochemistry is formed in the prior step. Furthermore. the role of the metal ion of the aza-enolate reagents and the steric demands of the O-alkyl ester group have been examined. It seems that the anti-diastereoselectivity depends on metal chelation by the oxygen of the ester as well as the oxygen of the sulfinyl group and the nitrogen in the aza-enolate ((Z)-configuration). In addition, the synthesis of methyl L-(2S,4S)-4-methyl-6-oxopipecolate has been achieved from the suitably functionalized 2-sulfinylketimine 1a (five steps; overall yield: 53-65%). (C) 2002 Elsevier Science Ltd. All rights reserved.