DIRECT AND ENANTIOSPECIFIC ORTHO-BENZYLATION OF PHENOLS BY THE MITSUNOBU REACTION

ortho-Substituted phenol derivatives with high optical purity have bee n obtained directly by Mitsunobu reaction between an appropriate pheno l and an optically active benzyl alcohol, In this reaction, the chemic al yield was well balanced with the optical purity of the ortho-substi tuted compound when 5 equiv, of phenol was allowed to react with 1 equ iv, of alcohol in a solvent such as dichloroethane or toluene, In addi tion, it was confirmed by an X-ray analysis of the product that stereo chemical inversion of the asymmetric centre took place in this reactio n, as well as the usual Mitsunobu reaction, This reaction is useful in the preparation of optically active phenol derivatives possessing a d iarylmethane moiety.