Compounding Selectivity in Reactions of Diastereoisomeric Radical Intermediates. An experimental demonstration that the yield of a product from a diastereotopic-group-selective reaction can significantly exceed the level of group selectivity
作者:Dennis P. Curran、Hongyan Qi
DOI:10.1002/hlca.19960790104
日期:1996.2.7
one (6), with 3 equiv. of Ph3SnH provides mixtures of cis,cis- or cis,trans-angular triquinane products (3aα,5aβ,8β,8aR*)- and (3aα,5aα,8β,8aR*)-hexahydro-3a-propyl-8-phenyl-5H-dicyclopenta[b,c]furan-7(8H)-one (cis,cis-12/cis,trans-12), in yields that vary from 50%/50% to 91%/6% depending on the reaction concentration. A mechanistic model for this process is proposed that involves a non-selective
双自由基前体6-苯基-1,1-双[3-(苯基硒基丙基)丙基] -3a,4-二氢-1 H,3 H-环戊[ c ]呋喃-5-酮(6)的还原,具有3个当量。Ph 3 SnH的混合物提供顺式,顺式或顺式反角三喹烷产物(3aα,5aβ,8β,8a R *)-和(3aα,5aα,8β,8a R *)-六氢-3a-丙基-的混合物8苯基-5- ħ -dicyclopenta [ b,C ]呋喃-7-(8 ħ) -酮(顺式,顺式- 12 /顺式,反式- 12),根据反应浓度的不同,收率从50%/ 50%到91%/ 6%不等。提出了用于该过程的机械模型,该模型涉及非选择性苯基硒基团的提取步骤,然后是非对映异构自由基中间体的连续动力学拆分。该反应表明如何将组选择性反应中的产率复合到表面上高于组选择性步骤所允许的水平。