Rh-Catalyzed Asymmetric Hydrogenation of Unsaturated Medium-Ring NH Lactams: Highly Enantioselective Synthesis of N-Unprotected 2,3-Dihydro-1,5-benzothiazepinones

• DOI: 10.1021/acs.orglett.9b04478
• Publication Date: 2020-01-09T15:13:15Z
• Authors: Congcong Yin; Tao Yang; Yingmin Pan; Jialin Wen; Xumu Zhang
• Keywords: Asymmetric hydrogenation

A straightforward method to prepare 1,5-benzothiazepines was reported. Catalyzed by a Rh/Zhaophos complex, unsaturated cyclic NH lactams with medium-size ring were hydrogenated smoothly, giving remarkably high enantioselectivities. The sulfur atom in the substrates did not bring an inhibition which observed commercially available bisphosphine ligands. This successfully applied scale-up synthesis of (R)-(−)-thiazesim.