Highly stereoselective oxy-Michael additions to α,β-disubstituted nitro olefins: asymmetric synthesis of pseudo-norephedrine derivatives and THP* protected α-hydroxy ketones
作者:David J. Buchanan、Darren J. Dixon、Felix A. Hernandez-Juan
DOI:10.1039/b406804c
日期:——
delta lactol undergoes efficient oxy-Michael addition to alpha,beta-disubstituted nitro olefins to give the THP* protected Henry products with excellent (95-->98% de) stereocontrol at the beta-position and moderate (up to 3 : 1) stereocontrol at the alpha-position in favour of the syn-diastereoisomer. Nitro group reduction with in situN-Boc protection and THP* removal provides alpha,beta-disubstituted
(S)-6-甲基δ乳醇的“裸”阴离子在α,β-二取代的硝基烯烃上进行有效的氧-迈克尔加成反应,从而得到THP *保护的亨利产物,在90℃时具有出色的(95-> 98%de)立体控制。有利于顺-非对映异构体的β-位和中等(最高3:1)立体控制在α-位。通过原位N-Boc保护和THP *去除进行硝基还原可提供α,β-二取代的乙醇胺衍生物,而过钌酸四丙基铵处理则可得到非对映异构体过量的THP *保护的α-羟基酮衍生物。