Stereocontrolled Synthesis of 1, 5-Stereogenic Centers through Three-Carbon Homologation of Boronic Esters

Allylic pinacol boronic esters are stable toward 1,3-borotropic rearrangement. We developed a PdII-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.