Highly Efficient Asymmetric Access to 1-Azaspiro[4.4]nonane Skeleton
作者:Jacques Royer、Loïc Planas、Joëlle Pérard-Viret、Mohamed Selkti、Alain Thomas
DOI:10.1055/s-2002-34232
日期:——
Vinylogous Mukaiyama aldol type reaction of chiral non-racemic silyloxypyrroles followed by acidic treatment affords an efficient asymmetric access to 1-azaspiro[4.4]nonanes in high diastereoisomeric excess (up to 79%).
Stereoselective Synthesis of (−)-Cephalotaxine and C-7 Alkylated Analogues
作者:Loïc Planas、Joëlle Pérard-Viret、Jacques Royer
DOI:10.1021/jo049884l
日期:2004.4.1
A total asymmetric synthesis of (−)-cephalotaxine is reported. The chemistry of α,β-unsaturated γ-lactams was used to access the 1-azaspiro[4.4]nonane skeleton in enantiomerically pure form via a stereocontrolled semipinacolic rearrangement of an α-hydroxyiminium ion. This spiro compound was transformed into (−)-cephalotaxine without any racemization or epimerization by following the racemic synthesis