Epoxide opening transformations in syntheses of acyclic polyketides

This chapter describes the syntheses of acyclic polyketides by using epoxide opening reactions. Acyclic polyketides including polyacetates and polypropionates have attractive structures and bioactivities. Since acyclic polyketides possess a lot of stereogenic centers, methodologies to synthesize polyketides have been developed to obtain the desired stereoisomers. Especially, the acyclic stereocontrol reactions provide acyclic polyketide skeletons directly, so that straightforward synthetic routes toward polyketides have established by combination of acyclic stereocontrol reactions. In order to apply epoxide opening transformations to syntheses of polyketides, both epoxidation and epoxide opening reactions are required to proceed in stereoselective manners. The key reactions of the epoxide opening transformation and their applications to the natural product syntheses are described. In Introduction (Section 1), the stereoselective epoxidations of the allylic alcohols are briefly described. Not only catalytic asymmetric epoxidation reactions but also the stereospecific reactions due to substrate-control are frequently used to synthesize polyketides. From Section 2 to Section 8, a variety of epoxide opening reactions and applications in natural product synthesis are reviewed. Synthetic studies using epoxide opening reactions show how to use epoxides to prepare the desired compounds.