An enantioselective sulfa‐Michael‐cyclization reaction was developed for the synthesis of 1,5‐benzothiazepines with versatile pharmacological activities. The reaction between 2‐aminothiophenol and α,β‐unsaturated pyrazoleamides gave direct access to N−H‐free 1,5‐benzothiazepines in the presence of a chiral N,N′‐dioxide/Yb(OTf)3 complex. Excellent enantioselectivities (up to 96 % ee) and high yields
Catalytic Enantioselective Synthesis of Protecting-Group-Free 1,5-Benzothiazepines
作者:Sara Meninno、Chiara Volpe、Alessandra Lattanzi
DOI:10.1002/chem.201700837
日期:2017.4.3
2,3‐dihydro‐1,5‐benzothiazepinones, by an organocatalyzed sulfa‐Michael reaction of readily available α,β‐unsaturated N‐acyl pyrazoles with 2‐aminothiophenols followed by silica‐gel‐catalyzed lactamization, has been developed. The method proceeds under mild conditions at room temperature and it requires only 1 mol % catalyst loading, to give 2‐aryl/alkyl‐substituted 1,5‐benzothiazepines in generally
Formal [3 + 4] Annulation of α,β-Unsaturated Acyl Azoliums: Access to Enantioenriched N–<i>H</i>-Free 1,5-Benzothiazepines
作者:Chao Fang、Tao Lu、Jindong Zhu、Kewen Sun、Ding Du
DOI:10.1021/acs.orglett.7b01457
日期:2017.7.7
An unprecedented formal [3 + 4] annulation of α,β-unsaturatedacyl azoliums with 2-aminobenzenethiols has been utilized to synthesize enantioenriched N–H-free 1,5-benzothiazepines, which are recognized as privileged structures in numerous biologically active scaffolds. This protocol offers a rapid and direct pathway to access the target compounds with high enantioselectivities and has been applied
cyclic NH lactams with a medium-size ring were hydrogenated smoothly, giving remarkably high enantioselectivities. The sulfur atom in the substrates did not bring an inhibition which was observed with commercially available bisphosphine ligands. This method was successfully applied in the scale-up synthesis of (R)-(-)-thiazesim.