STUDIES ON SYNTHESES OF HETEROCYCLIC-COMPOUNDS .783. PHOTOOXYGENATION OF 9-OXO-9H-PYRROLO[1,2-A]INDOLES

Photo-oxygenation in methanol of 7-methoxy-6-methyl-9-oxo-9H-pyrrolo[1,2-a] indole (10), prepared from 2-bromo-5-methoxy-4-methylbenzaldehyde (5) via 2-(2-bromo-5-methoxy-4-methylbenzoyl)pyrrole (8), formed (±)-9,9a- dihydro-3α-hydroperoxy-9-oxo-7,9aβ-dimethoxy-6-methyl-3H-pyrrolo[1, 2-a]indole (14) and the (±)-3α-hydroxy-compound (16). The corresponding 9a-ethoxy- (20) and 9a-isopropyloxy-derivatives (21) were obtained from the photo-oxygenation of compound (10) in ethanol and isopropyl alcohol, respectively. The dyesensitized photo-oxygenation of 9-oxo-6,7-dimethoxy-9H- pyrrolo[1,2-a]indole (11) was also carried out in methanol.