Asymmetric epoxidation of cis-1-propenylphosphonic acid (CPPA) catalyzed by chiral tungsten(VI) and molybdenum(VI) complexes

In the presence of 5.0 mol% chiral tungsten(VI) and molybdenum(VI) complexes, the catalytic asymmetric epoxidation of cis-1-propenylphosphonic acid (CPPA) with 30% aqueous H2O2 affording (1R,2S)-(−)-(1, 2)-epoxypropyl phosphonic acid (fosfomycin) was first described. The enantioselectivities of the tungsten and molybdenum catalysts depend strongly on the ligands, reaction temperature and solvent. In CH2Cl2 at 0 °C for 72 h, complex MoO2[(+)-campy]2 catalyzed the asymmetric epoxidation in a 100% conversion of CPPA with the highest 80% ee. The mechanism of the present epoxidation could be described as direct oxygen transfer occurred on the interface of the biphasic H2O–nonprotic system.