Enantioselective Hydroxylations of Benzylic C-H Bonds Using Biocatalysis

Significance

A highly enantioselective benzylic hydroxylation of benzene derivatives containing reactive functional groups employing resting cells of Pseudomonas monteilii TA-5 as a biocatalyst is reported. Based on experimental results it is suggested that an NADH- or NADPH-dependent monooxygenase in the resting cells is responsible for the benzylic hydroxylation. The synthetic utility of this transformation is demonstrated by conducting it on a 0.8 mmol scale where benzylic alcohol 2 was obtained in 56% yield with a slightly decreased enantiomeric ratio of 97:3. Remarkably products 1 and 3 are the first examples of enan­tioselective benzylic hydroxylations of these substrates.