2,4-Diaryl-2,3-dihydrobenzo[b][1,4]thiazepines

2,4-Diaryl-2,3-dihydrobenzo[b][1,4]thiazepines are obtained in a single stage from chalcones and ortho-aminothiophenol in the presence of triethylamine. The nature of the electronic transitions in their UV absorption spectra is discussed with the use of quantum-chemical methods. It was shown that the seven-membered ring does not invert in the range of temperatures between –80 and +140 °C and is in the boat form. The main initial event in the fragmentation of the molecules of the obtained compounds under electron impact is the formation of benzothiazole-containing radicalions. In an acidic medium 2,4-diphenyl-2,3-dihydrobenzo[b][1,4]thiazepine is hydrolyzed to 3-(2-aminophenylthio)-1,3-diphenyl-1-propanone, and in its reaction with 2,4-dinitrophenylhydrazine chalcone hydrazone and o-aminothiophenol are formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1638–1642, December, 1983.