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.