SYNTHESIS OF 4,6-DIHYDRO-4-OXOPYRIDO[2,1-A]ISOINDOLES AND 4,6-DIHYDRO-6-OXOTHIENO[2',3'/3,4]PYRROLO[1,2-A]PYRIDINES

Tricyclic pyridones (3) which are important intermediates for the preparation of potent benzodiazepine receptor ligands were obtained by different chemical routes. Key reaction in the so far optimal synthesis of 3a is the base catalyzed ring contraction reaction of 2 to intermediate (13). Under similar reaction conditions, however, thiophene derivative (14) yielded instead of the analogous acid (16), the nitrile (15). In two additional steps the final product (3b) was obtained in good yield.