A Convenient Synthesis of 1,4-Benzothiazepines from 1,3-Benzothiazines via the Ring Transformation of p-Lactam-Condensed 1,3-Benzothiazine Derivatives

摘要

A convenient synthesis was devised for rare 2,3-disubsti-tuted 4,5-dihydro-l,4-benzothiazepines from 2-aryl-4H-l,3-ben-zothiazines. The Staudinger reaction of 1,3-benzothiazines obtained with chloroacetyl chloride selectively furnished trans-monochloro-beta-lactam-condensed thiazines. The ring expansion of azeto[2,l-i][l,3]benzothiazin-l-one derivatives with sodium methoxide afforded 1,4-benzothiazepines as the sole product in good yields. The structures of the new molecules were proved by means NMR and IR spectroscopy.