Catalytic asymmetric conjugate boration of alpha,beta-unsaturated sulfones

The alpha,beta-unsaturated sulfones are suitable activated olefins in catalytic asymmetric conjugate beta-boration. These substrates undergo smooth conjugate addition of bis(pinacolato) diboron [B(2)(pin)(2)] catalyzed by nonracemic Cu(I)-diphosphine complexes to provide, upon subsequent oxidation, beta-hydroxy sulfones in good yields and high enantiocontrol.