2-amidinylindole-3-carbaldehydes: Synthesis of new tetracyclic compounds containing the pyrrolo[1,2-c]1,4-diazepine ring

2-Amidinylindol-3-carbaldehydes bearing an alpha-alkoxycarbonyl substituent on the cyclic-tertiary amine moiety were prepared. Pyrolysis of these amidines in diethylenglycol-monoethyl ether produced mainly a pyrrolo[ 1',2'-1,2]-1,4-diazepino[5,6-b]indol-7,11-dione. A similar result was obtained starting from 2-amidinylbenzofuran-3-carbaldehyde.