Stereopure 1,3-butadiene-2-carboxylates and their conversion into non-racemic α-alkylidenebutyrolactone natural products by asymmetric dihydroxylation
作者:Christian Harcken、Reinhard Brückner
DOI:10.1016/s0040-4039(01)00598-6
日期:2001.6
Dienoic esters 1 with the four possible permutations of the C=C configurations were prepared in two steps via non-stereoselective aldol additions followed by stereospecific beta -eliminations. Sharpless dihydroxylations of these esters yielded natural and unnatural alpha -alkylidene-beta -hydroxybutyrolactones 2. Among these were synthetic dihydromahubanolide B (cis,Z-2a), isodihydromahubanolide B (cis,E-2a) and, for the first time, litsenolide D-1 (ent-trans,Z-2b) and the enantiomer trans,E-2b of litsenolide D-2. Competitively, dihydroxyesters 10 were formed. (C) 2001 Elsevier Science Ltd. Al rights reserved.