Molybdenum-catalyzed asymmetric anti-dihydroxylation of allylic alcohols

Abstract

Asymmetric dihydroxylation of alkenes is one of the fundamental reactions in organic synthesis, but the anti-dihydroxylation is much less developed than its syn-variant. Here we report a highly enantio- and diastereoselective anti-dihydroxylation of allylic alcohols by using a chiral molybdenum-bishydroxamic acid complex as catalyst and environmentally benign hydrogen peroxide as oxidant. This reaction enables the construction of the 1,2,3-triol structural unit in high enantio- and diastereocontrol starting from simple allylic alcohol precursors. Our reaction complements the Sharpless dihydroxylation not only in its diastereoselectivity, but also in regiocontrol. The mechanistic studies indicate that this dihydroxylation reaction consists of an initial enantioselective epoxidation and the following in situ regioselective ring opening, both of which are promoted by the molybdenum-catalyst.