Synthesis and structure–activity relationship studies of novel tubulysin U analogues – effect on cytotoxicity of structural variations in the tubuvaline fragment
Studies towards a Novel Synthesis
of Tubulysins: Highly Asymmetric Aza-Michael Reactions
of 2-Enoylthiazoles with Metalated Chiral Oxazolidinones
作者:Matteo Zanda、Monica Sani、Giancarlo Terraneo
DOI:10.1055/s-0029-1216729
日期:——
Herein we report the highly asymmetric aza-Michael reactions of α,β-enones (2-enoylthiazoles) with metalated chiral oxazolidinones under different reaction conditions and for different substituents at the β-position of the Michael acceptor. The reaction proceeds with complete diastereoselectivity to give exclusively one of the two diastereomers. The significance of the reaction is that no catalyst has been used; the steric requirements of the chiral Michael nucleophile drive the stereospecificity of the reaction and the reaction time is much less compared to the reported procedures. This methodology might be useful for an improved total synthesis of the highly cytotoxic peptides known as the tubulysins.