effective synthetic methods stands in stark contrast to the large number of encumbered sites encountered in molecules of interest. Here, we demonstrate that 1,2-bis(boronates) undergo selective alkynylation and alkenylation at the more sterically hindered C–B bond. Our preliminary mechanistic studies disclosed that this reaction can proceed through two convergent pathways involving direct coupling of sterically
Stereocontrolled Synthesis of 1,5-Stereogenic Centers through Three-Carbon Homologation of Boronic Esters
作者:Phillip J. Unsworth、Daniele Leonori、Varinder K. Aggarwal
DOI:10.1002/anie.201405700
日期:2014.9.8
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‐stereogeniccenters. The utility of this method has been demonstrated in a formal