Synthesis of aryl substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine3-thionesi/ones starting from chalcone-derived β-isothiocyanato ketones

A general two-step synthesis of 7-aryl substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones from 1-aryl-3-isothiocyanatopropan-1-ones has been developed. The synthesis involved reaction of these isothiocyanato ketones with hydrazines followed by acid-catalyzed heterocyclization of the prepared 4(3-oxopropyl)thiosemicarbazides or their hydrazones. Triazepine-3-thiones were converted into their 3oxo analogs by oxidation with H2O2 under basic conditions. Conformations of the obtained triazepine-3thiones/ones in DMSO solution and in solid state were established using H-1 NMR spectroscopy and single crystal X-ray diffraction. (C) 2016 Elsevier Ltd. All rights reserved.