Synthesis of 7-Oxabicyclo[2.2.1]heptanes and 8-Oxabicyclo[3.2.1]octanes from C-Glycosides via an Intramolecular Cyclization
作者:Wei Zou、Kannan Vembaiyan
DOI:10.1021/jo3024973
日期:2013.3.15
A simple and effective method for the synthesis of 7-oxabicyclo[2.2.1]heptanes and 8-oxabicyclo[3.2.1]octanes from acetonyl C-glycoside substrates is described, which involves an intramolecular cyclization reaction through a nucleophilic substitution at C-5 or C-6 of C-glycosides by a 2′-enamine intermediate formed in the presence of pyrrolidine. Because anomeric epimerization occurs under these conditions
描述了一种从丙酮酰基C-糖苷底物合成7-氧杂双环[2.2.1]庚烷和8-氧杂双环[3.2.1]辛烷的简单有效的方法,该方法涉及通过C-端的亲核取代进行分子内环化反应。通过在吡咯烷存在下形成的2'-烯胺中间体形成C-糖苷的5或C-6。因为在这些条件下发生异头异构体差向异构化,所以具有任一异头异构体构型的C-糖苷底物都以相同的立体选择性和相似的化学产率转化为相同的产物。