Some 1,3-Dipolar Adducts from Benzodiazepine. I. Condensation of Nitrilimines with 2-Methyl-4-phenyl-1,5-benzodiazepines

The condensation reaction of N-p-nitrophenyl-C-ethoxycarbonyl nitrilimine or N-p-chlorophenyl-C-ethoxycarbonyl nitrilimine with 7-X-2-methyl-4-phenyl-1,5-benzodiazepine (X = H or CH₃) is regio- and periselective. The 1,3-dipolar cycloaddition occurs in a unique way on the N1=C2 double bond of the 1,5-benzodiazepine and leads to ethyl 3a-methyl-3-(4-nitrophenyl)-5-phenyl-3a,4-dihydro-3H-[1,2,4]triazolo[4,3-a] [1,5]benzodiazepine-1-carboxylate, C₂₆H₂₃N₅O₄ (3a), or ethyl 3a,8-dimethyl-3-(4-chlorophenyl)-5-phenyl-3a,4-dihydro-3H-[1,2,4]triazolo[4,3-a] [1,5]benzodiazepine-1-carboxylate, C₂₇H₂₅ClN₄O₂ (3b).

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