1H-pyrrolo[2,3-b]pyridines. Part III. A novel synthetic route from 1-substituted 2-aminopyrroles
Abstract
A variety of 1-alkyl- and 1-aryl-2-amino-4-cyanopyrroles have been shown to undergo condensation with 1,3-dicarbonyl compounds and their acetals, β-oxo-esters, and diethyl malonate in the presence of hydrochloric acid to yield, in one stage, 1H-pyrrolo[2,3-b]pyridines. With ethyl ethoxymethylenemalonate, 2-bis(ethoxycarbonyl)vinylaminopyrroles were isolated, and thermally cyclised to ethyl 4,7-dihydro-4-oxopyrrolo[2,3-b]-pyridine-5-carboxylates. Spectroscopic evidence has been obtained for the structures of all the products.