Asymmetric ring cleavage reaction with a combination of optically active cycloalkane-1,2-diol and Lewis acid: application to formal synthesis of (−)-alloyohimbane and approach to construction of adjacent chiral quaternary centers

Asymmetric ring cleavage reaction of meso-carbobicyclic ketones by a combination of benzaldehyde, chiral cycloalkane-1,2-diol, and Lewis acid gave optically active styrenyl esters of 26-69% ee in moderate yield. The ring cleavage reaction could be applied to the construction of adjacent chiral quaternary carbons, and also to the formal synthesis of natural alkaloid (−)-alloyohimbane.