Improved synthesis of the polyhydroxylated central part of phoslactomycin B
摘要:
A new approach to the C(7)-C(13) intermediate for the synthesis of phoslactomycin B was investigated. Asymmetric dihydroxylation of the beta,gamma-unsaturated ester proceeded cleanly to afford the beta-hydroxyl-gamma-lactone with 97.6% ee, which upon protection as the PMB ether followed by hydride reduction furnished a diol. After selective protection of the prim-OH, oxidation of the see-OH and chelation-controlled addition of CH2=CHMgBr afforded the C(7)-C(11) segment. Later on, the C(11) stereocentre was constructed by the asymmetric transfer hydrogenation using the Noyori catalyst. (c) 2007 Elsevier Ltd. All rights reserved.
Stereoselective Syntheses of Rolliniastatin 1, Rollimembrin, and Membranacin
摘要:
A radical cyclization of beta-alkoxyvinyl sulfoxides-Pummerer rearrangement-allylation protocol was successfully applied to the synthesis of the threo/cis/threo/cis/erythro bis-oxolane moiety in rolliniastatin 1 (1), rollimembrin (2), and membranacin (3).