Highly diastereoselective [2+2] cycloadditions via chelation control: Asymmetric synthesis of β-lactones
作者:Ronald Zemribo、Daniel Romo
DOI:10.1016/0040-4039(95)00716-p
日期:1995.6
Chelation controlled [2+2] cycloadditions of trimethylsilylketene to chiral alpha- and beta-benzyloxyaldehydes followed by desilylation provides a highly diastereoselective route to functionalized beta-lactones. Several Lewis acids were examined and MgBr2 . Et(2)O was found to give the highest diastereoselectivities and yields.
Hybrid polyketide synthase I gene
申请人:Biotica Technology Limited
公开号:EP0910633B1
公开(公告)日:2009-12-09
(+)-11,11′-Di-O-methylelaiophylidene – preparation from elaiophylin and total synthesis from (R)-3-hydroxybutyrate and (S)-malate
作者:Dieter Seebach、Hak-Fun Chow、Richard F. W. Jackson、Marius A. Sutter、Suvit Thaisrivongs、Jürg Zimmermann
DOI:10.1002/jlac.198619860714
日期:1986.7.14
methanol, with replacement of two lactol OH-groups by OCH3 (C-11 and C-11′). The di-O-methylelaiophylidene (8a), a C2-symmetrical macrodiolide with 2 × 11 stereogenic units, was synthesised from (R)-3-hydroxy-butanoate (from the biopolymer PHB) and (S)-malic ester, using diastereoselective steps for the generation of the other stereogenic units. The key intermediates (Scheme 2) are the macrocyclic dialdehyde