摘要
An efficient and practical organocatalytic asymmetric[3+2]cycloaddition of difluoromethylated ketoimines and methyleneindolinones catalyzed by a quinine-derived squaramide has been disclosed.Under mild conditions,a broad range of CF_(2)H-containing dispiro[benzo[b]thiophene-oxindole-pyrrolidine]s bearing four adjacent chiral centers including two vicinal spiro quaternary stereocenters were obtained in high yields(up to 99%yield)with excellent diastereoselectivities(>20:1 dr,in all cases)and enantioselectivities(up to 99%ee).
基金
the National Natural Science Foundation of China(no.81872723 and 82073679).
