REACTIONS OF 2-HYDRAZINO-1-AZAAZULENES WITH DIPHENYLCYCLOPROPENONE

The reaction of ethyl 2-hydrazino-1-azaazulene-3-carboxylate with diphenylcyclopropenone (DPP) gave ethyl (Z)-2-[N'-(3-amino-2,3-diphenylpropenoyl)hydrazino]-1-azaazulene-3-carboxylate, ethyl 8,9-diphenyl-1,2,9b-triazaindeno[1,7,6-bcd]azulene-3-carboxylate, ethyl (E)-3-(1,2-diphenylethyl)-1,2,3a-triazacyclopent[a]-azulene-9-carboxylate, and ethyl 2-amino-1-azaazulene-3-carboxylate (8a), together with the products of 8a with DPP. However, the reaction of 2-hydrazino-1-azaazulene with DPP gave 4H-2,3-diphenyl-1,4a-diazabenz-[a]azulen-4-one, (Z)-3-[(1-azaazulen-2-yl)amino]-2,3-diphenylpropenamide, 3,4-diphenyl-3,4-dihydro-2H-1,4a-diazabenz[a]azulen-2-one and 2-amino-1-azaazulene. The structures of the obtained products were determined by inspections of their physical and spectral data, as well as single-crystal X-ray structure analyses of some of these compounds. The reaction mechanisms are discussed.