Complex fragment coupling by crotylation: a powerful tool for polyketide natural product synthesis

Abstract

The first examples of the use of crotylation as a stereocontrolled complex fragment coupling strategy are described. Asymmetric aldehyde isoprenylation provides access to 2-substituted-1,3-butadienes that may be subjected to highly regio- and stereoselective 1,4 hydrosilylation with trichloro-silane. After complexation with a chiral diamine, the 2-substituted-cis-crotylsilanes may be employed in highly diastereoselective Sc(OTf)₃-catalyzed aldehdye crotylation reactions.