C2‑Symmetric 1,2-Diphenylethane-1,2-diamine-Derived Primary–Tertiary Diamine-Catalyzed Asymmetric Mannich Addition of Cyclic N‑Sulfonyl Trifluoromethylated Ketimines
journal contributionposted on 2020-08-25, 13:42 authored by Hui-Xin Duan, Yongna Zhang, Zhen-Zhen Zhang, You-Qing Wang
A simple chiral primary–tertiary diamine derived from C2-symmetric 1,2-diphenylethane-1,2-diamine as the organocatalyst in combination with the trifluoroacetic acid additive for the asymmetric Mannich reaction of cyclic N-sulfonyl trifluoromethylated ketimines and methyl ketones afforded the desired product with high enantioselectivity (73–96% ee). The reactions proceeded well for a variety of different substituted cyclic N-sulfonyl trifluoromethyl ketimines and various alkyl methyl ketones, providing access to diverse enantioenriched benzo-fused cyclic sulfamidate N-heterocycles bearing a trifluoromethylated α-tetrasubstituted carbon stereocenter. This study also investigated the diastereoselective reduction of the carbonyl group and ring cleavage reduction of the sulfamidate group of the corresponding Mannich product.