Anionic Chiral Co(III) Complexes Mediated Asymmetric Halocyclization-Synthesis of 5-Halomethyl Pyrazolines and Isoxazolines

An asymmetric synthesis of 5-halomethyl pyrazolines and isoxazolines which bear a tertiary stereocenter by catalytic halocyclization of beta,gamma-unsaturated hydrazones and ketoximes is described. By using Bronsted acids of anionic chiral Co(III) complexes as catalysts, a variety of chiral 5-halomethyl pyrazolines and isoxazolines were obtained in good yields with high enantioselectivities (up to 99% yield, 97:3 er). Preliminary bioassay results indicated that several isoxazoline derivatives exhibited significant antifungal activities.

Automated summary

An asymmetric synthesis of 5-halomethyl pyrazolines and isoxazolines bearing a tertiary stereocenter was achieved through catalytic halocyclization of beta,gamma-unsaturated hydrazones and ketoximes. The use of Bronsted acids of anionic chiral Co(III) complexes as catalysts led to the formation of chiral compounds with high yields and enantioselectivities. Preliminary bioassay results showed that some isoxazoline derivatives exhibited significant antifungal activities.