N. Abe, A. Kakehi,
Jun 1, 1992
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Journal
Bulletin of the Chemical Society of Japan
Abstract
We synthesized Schiff bases, ethyl 2-[2-(benzilideneamino)anilino]cyclohepta[b]pyrrole-3-carboxylate (2a) and ethyl 2-[2-(2-butenylideneamino)anilino]cyclohepta[b]pyrrole-3-carboxylate (2b), from ethyl 2-(2-aminoanilino)cyclohepta[b]pyrrole-3-carboxylate (1) in excellent yields by treating 1 with benzaldehyde or 2-butenal in the presence of molecular sieves 4A, respectively. Further, the cyclization and cycloaddition reactions of the Schiff bases were investigated. Treatment of 2a with iron(III) chloride or Pd–C gave ethyl 2-(2-phenylbenzimidazol-1-yl)cyclohepta[b]pyrrole-3-carboxylate and 12H-5,13-dihydrocyclohepta[1′,2′ : 4,5]pyrrolo[2,3-b][1,5]benzodiazepin-12-one (4). A similar treatment of 2b, however, gave ethyl 2-(4-methylqinolin-8-yl)aminocyclohepta[b]pyrrole-3-carboxylate and 4. The reaction of 2a with dimethyl acetylenedicarboxylate (DMAD) gave 15a-ethyl 5,6,7,15-tetramethyl 15,15a-dihydro-14H-pyrrolo[2′,1′ : 1,2]isoquino[3,4-b][1,5]benzodiazepine-5,6,7,15,15a-pentacarboxylate (6) and methyl 4-(...