Researches on thiazolobenzodiazepines: Behavior of tetrahydro-1,5-benzodiazepinethiones with aromatic α-haloketones

A number of 1-substituted 4H,5H,6H-[1,3]thiazolo[3,2-a][1,5]benzodiazepinium-11-bromides and S-(2-oxo-2-phenyl-X-(p)-ethyl)-3-(2-methyl-1H-benzimidazol-1-yl) propane (or butane) thioate hydrobromides were obtained by direct reaction of the 5-acetyl(or formyl, or anilinocarbonyl)-substituted tetrahydro-1,5-benzodiazepine-2-thiones with aromatic α-bromoketones. 2-[(1-Acetyl-2(or 3)-methyl-2,3-dihydro-1H-1,5-benzodiazepin-4-yl) sulfanyl]-1-phenylethanones as intermediates of the formation of thiazolo [3,2-a][1,5]benzodiazepine and N-substituted 2-methyl-1H-benzimidazole derivatives have been synthesized. Semiempirical AM1 calculations of a mechanism and energetic parameters for the heptatomic nucleus rearrangement to benzimidazole ring are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:72–81, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20414