Stereoselective synthesis of (−)-metasequoic acid B

Abstract

A stereoselective synthesis of the ent-labdane diterpene (-)-metasequoic acid B (ent-2) and its corresponding methyl ester (ent-3) starting from (R)-(-)-carvone 6 is described. The synthesis is based on the construction of a phenanthrenone system 5 which is converted into the ent-labdane skeleton after selective cleavage of the C(13)–C(14) bond.