Synthesis of Highly-Substituted Enantiomerically Pure Allylboronic Esters and Investigation of Their Stereoselective Addition to Aldehydes

Diastereomerically
pure allylboronates bearing the readily available
tartrate derivative were obtained via sigmatropic rearrangement. Allyl
additions were performed, and the influence of γ-disubstituted
allylboronates was studied. Highly γ-substituted boronic esters
were found to lead to the corresponding enantiomerically enriched
homoallyl alcohols with exclusively E configuration;
their synthesis and the mechanism of the reaction is proposed here.