Stereocontrolled synthesis of 1,5-stereogenic centers through three-carbon homologation of boronic esters

Abstract

Allylic pinacol boronic esters are stable toward 1,3-borotropic rearrangement. We developed a Pd(II)-mediated isomerization process that gives di- or trisubstituted allylic boronic esters with high E selectivity. The combination of this method with lithiation-borylation enables the synthesis of carbon chains that bear 1,5-stereogenic centers. The utility of this method has been demonstrated in a formal synthesis of (+)-jasplakinolide.

Keywords: 1,5-stereocenters; allylic boronic esters; asymmetric synthesis; lithiation-borylation; palladium.