SYNTHESIS OF 2-SUBSTITUTED -DIHYDRO-9-PHENYL-1H-PYRROLO[3,4-B]QUINOLIN-3-ONES AS POTENTIAL PERIPHERAL BENZODIAZEPINE-RECEPTOR LIGANDS

Two synthetic routes to the achievement of the title compounds are des cribed. 2-Chloromethyl-3-ethoxycarbonyl-4-phenylquinoline (4) was tran sfomed into the corresponding lacton (5) which in two steps was conver ted into its isomeric lacton (7). Aminolysis of 7 gave gamma-hydroxyam ide (8) which was in turn transformed into gamma-chloroamide (9). Cycl ization of 9 with sodium hydride in presence of oxygen led to the oxid ized compound (10), while by carrying out the cyclization reaction und er inert atmosphere, 3-dihydro-9-phenyl-1H-pyrrolo[3,4-b]quinolin-3-on e (3a) was obtained. Autoxidation of anion at 1-position of compound ( 3a) was considered to account for these results and a mechanistical in terpretation was given. A simplier and more versatile route to obtain the title compounds was also developed.