A new variant of the Claisen rearrangement from malonate-derived allylic trimethylsilyl ketene acetals: Efficient, highly enantio- and diastereoselective syntheses of (+)-methyl dihydroepijasmonate and (+)-methyl epijasmonate

Abstract

Complete chirality transfer occurs in the smooth Claisen rearrangement of the trimethylsilyl (TMS) ketene acetals, which were prepared from allylic malonates (R)-1 (R = pentyl, 2-(Z)-pentenyl). These are in turn accessible by enantioselective reduction/esterification or by enzymatic kinetic resolution. The cis configuration in (+)-3 was achieved by highly syn-selective epoxidation of (+)-2, followed by suprafacial 1,2-H migration.