Microwave-accelerated enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl)imines catalysed by β-aminoalcohols with the prolinol skeleton

Abstract

The addition of dialkylzinc reagents to N-(diphenylphosphinoyl)imines in the presence of a catalytic amount of a β-aminoalcohol with the prolinol framework under microwave irradiation gives the expected addition products in good yields and with an ee of up to 92%. The reaction times (20–30 min) are much shorter than the ones observed in the same reactions performed at room temperature without microwave irradiation. In most cases, in the microwave-promoted reactions yields improve and enantiomeric excesses are very close to the ones achieved in the reactions stirred at room temperature. High enantioselectivities are obtained in the addition of dialkylzincs to both aromatic and aliphatic imines.