Decarboxylative Grob-Type Fragmentations in the Synthesis of Trisubstituted Z Olefins: Application to Peloruside A, Discodermolide, and Epothilone D

Prantz, Kathrin; Mulzer, Johann.   

Angewandte Chemie, International Edition  (2009),  48(27),  5030-5033, S5030/1-S5030/105.

Discriminating elimination: A new method for the synthesis of methyl-branched trisubstituted Z olefins, a structural motif in many polyketides with anticancer activity, relies on an -OH-induced decarboxylative Grob-type fragmentation (see scheme; Ms=mesyl). The starting materials are beta-mesyloxy lactones with a quaternary alpha center, which are prepared by aldol reactions in a diastereo- and enantioselective manner.