5.3.2 Vanadium-Catalyzed Epoxidation

Few Studies are focused on chiral vanadium catalyzed the epoxidation of allylic alcohols. The epoxidation of homoallylic alcohol has been found to be successful (Scheme 8).

Examples:

Scheme 8

5.3.3 Niobium-Catalyzed Epoxidation

Chiral niobium-complexes catalyze the epoxidation of allylic alcohols in the presence of hydrogen peroxide (H₂O₂) or urea hydrogen peroxide (UHP). From environmental and economic standpoint, this process is more attractive because it is atom economical and generates water as by-product. For example, [(μ-oxo){Nb(salan)}₂] 20 catalyzes the epoxidation of allylic alcohols in the presence of UHP at ambient conditions (Scheme 9-10).

Scheme 9

Scheme 10