摘要:
The C21-C34 subunit 27 of the aplyronines, containing eight stereocentres and a terminal N-methyl-N-vinylformamide moiety, was prepared using the Horner-Wadsworth-Emmons coupling of beta-ketophosphonate 5 with aldehyde 19. The two stereotetrad sequences were constructed by chiral ketone aldol reactions, while the N-methyl-N-vinylformamide was introduced using a novel Wittig olefination. (C) 2002 Elsevier Science Ltd. All rights reserved.