ChemInform Abstract: Unexpected Pyrazolo(4,3-d)(2,3)benzodiazepine Synthesis from 1-(N,N- Diaroyl)amino-4-phenyl(1,2,3)triazol-5-yl-methyltriphenylphosphonium bromide via Tandem Phosphorylide Formation and Subsequent Dimroth-Like Rearrangement of the Tria

1-(N,N-Diaroyl)amino-4-phenyl-1,2,3-triazol-5-yl-methyltriphenylphosphonium bromide 2 reacted with potassium t -butoxide or triethylamine in dry toluene giving the very stable phosphorus ylide 5 . Refluxing of 5 in xylene gave the unexpected 3-aroyl-6-arylpyrazolo[4,3- d ][2,3]benzodiazepines 6 by a Dimroth-like rearrangement of the triazole ring and a 1,7-electrocyclization of the nitrilimine intermediate 11 . When the xylene solution was not rigorously refluxed the 3(5)-aroyl-5(3)-phenyl pyrazole 7 was isolated. The x-ray crystal structures of compounds 5d and 6b are also given.