Asymmetric weitz - scheffer epoxidation promoted by bovine serum albumin. Part III. Highly stereoselective synthesis of optically active epoxynaphthoquimones

The epoxidation of 2-substituted naphthoquinones with t-BuOOH in an aqueous buffer solution containing a small amount (up to 5 % molar equiv) of bovine serum albumin (BSA) gives the corresponding epoxides with enantiomeric excess (e.e.) up to 100 %. The enantioselectivity is very sensitive to the addition of water miscible or immiscible cosolvents and to the length of the alkyl chain in position 2. The mechanism by which the cosolvents influence the e.e. was studied. Correlations between the circular dichroism spectra of the BSA-quinone complexes and the stereochemistry of the epoxidation products were found. © 1988.