A Chiral Imidazoline-phosphoric Acid Catalyst Usable for the Desymmetrizating Reaction of meso-Aziridine Derivatives

1, composed of an imidazoline moiety and a binaphthyl moiety, is an optically active phosphoric acid derivative developed by Nakamura et al. and it is used as a catalyst for the enantioselective desymmetrizating reaction of symmetric aziridines. A trans-β-thiocyanate is given in good enantioselectivity by the treatment of trimethylsilylisothiocyanate (TMSNCS) with N-2-pyridylsulfonyl group-substituted symmetric aziridines (2) in the presence of a catalytic amount of 1, calcium methoxide and molecular sieves. The synthetic process is presumed to proceed via the formation of an octahedral Ca cation complex intermediate coordinated with the imidazoline nitrogen atom of the catalyst 1, and the oxygen and nitrogen atoms on the 2-pyridylsulfonyl group of 2. The products are expected to be useful for the synthesis of bioactive compounds such as taurine derivatives because they can be converted into optically active β-aminothiols or β-aminosulfonic acids.