Anti-Selective dihydroxylation reactions of monosubstituted and (E)-ester conjugated allylic amines by bulky alkyl groups

The OsO₄-catalyzed dihydroxylations of a monosubstituted allylic amine and γ-amino-α,β-unsaturated (E)-esters with bulky alkyl groups showed a high anti-selectivity. Since the acyclic conformation of N-acyloxy protected allylic amines was efficiently controlled by a bulky t-Bu or OBO ester group, the anti diastereoselectivity of >12.5:1 was obtained without applying a chiral reagent. The synthetic utility of the present method was demonstrated by a stereoselective and efficient synthesis of an α-glucosidase inhibitor 15 from commercially available N-Cbz-L-serine 6 in 11 steps and 31% yield.