Oxazepines and thiazepines, XXI: CD-spectra of optically active 2-methyl-2,3-dihydro-1,5-benzothiazepin-4(5H)-ones and related 3-phenylthio-butyric acid derivatives
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