A highly enantioselectivecatalytic protocol for the desymmetrization of meso-aziridines via ring-opening with pyrazoles is reported using an N,N′-dioxide-Mg(OTf)2 complex as the catalyst. The corresponding trans-α-pyrazole-substituted amines were obtained in good yields and enantioselectivities (up to 99% yield and 94% ee) under mild reaction conditions. Moreover, a remarkably high asymmetric amplification