The present invention relates to a recyclable method to prepare chirally
pure epoxides directly from olefins using a novel chiral acid
2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid monohydrate as chiral
inducer and anhydrous hydrogen peroxide in the form of urea hydrogen
peroxide adduct (UHP) as oxidant and lipase enzyme as catalyst. Under the
influence of lipase, the chiral acid
2,3:4,6-di-O-isopropylidene-2-keto-L-gulonic acid monohydrate is
converted to per-acid in situ by the oxidant urea hydrogen peroxide which
in turn transfers oxygen to olefin inducing chirality to the product
epoxide. Using this technique, important epoxide building blocks of
different industrially important compounds can be prepared with good
yield and moderate enantioselectivity. Chiral epoxidation of olefins with
environment friendly catalytic system that can be recycled is highly
desirable in the context of Green Chemistry for preparation of many
industrially important compounds.