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Communication | Special issue | Vol 37, No. 1, 1994, pp.239-243
Published online, 1st January, 1970
DOI: 10.3987/COM-93-S41
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

Serge Burner, Rolf Canesso, and Ulrich Widmer*

*Pharma Division, Preclinical Research, F.Hoffmann-La Roche Ltd., CH-4002 Basel, Switzerland


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.