Asymmetric Synthesis of Diarylmethyl Sulfones by Palladium-Catalyzed Enantioselective Benzylic Substitution: A Remarkable Effect of Water.

A Pd/(R)-BINAP-catalyzed enantioselective benzylic sulfonation of diarylmethyl carbonates with sodium sulfinates proceeds to deliver the corresponding chiral diarylmethyl sulfones in good yields with high enantioselectivity. The reaction occurs in a dynamic kinetic asymmetric transformation (DYKAT) manner and thus provides convergent access to optically active benzylic sulfones from racemic secondary benzylic carbonates. Additionally, the addition of H O is found to be critical for high enantioselectivity.