Enantioselective Radical Construction of 5-Membered Cyclic Sulfonamides by Metalloradical C–H Amination

• DOI: 10.1021/jacs.9b08894
• Publication Date: 2019-10-17T19:15:12Z
• Authors: Yang Hu; Kai Lang; Chaoqun Li; Joseph B. Gill; Isaac Kim; Hongjian Lu; Kimberly B. Fields; McKenzie Marshall; Qigan Cheng; Xin Cui; Lukasz Wojtas; X. Peter Zhang
• Keywords: Azides; Sulfonamides; Coordination Complexes; Stereoisomerism; Cobalt; 01 natural sciences; Catalysis; Amination; Cyclic S-Oxides; 0104 chemical sciences

Both arylsulfonyl and alkylsulfonyl azides can be effectively activated by the cobalt(II) complexes of D2-symmetric chiral amidoporphyrins for enantioselective radical 1,5-C-H amination to stereoselectively construct 5-membered cyclic sulfonamides. In addition to C-H bonds with varied electronic properties, the Co(II)-based metalloradical system features chemoselective amination of allylic C-H bonds and is compatible with heteroaryl groups, producing functionalized 5-membered chiral cyclic sulfonamides in high yields with high enantioselectivities. The unique profile of reactivity and selectivity of the Co(II)-catalyzed C-H amination is attributed to its underlying stepwise radical mechanism, which is supported by several lines of experimental evidence.