Intramolecular cycloaddition of (allylimino)ketens: access to 3-azabicyclo[3.2.0]hept-2-en-7-ones
Abstract
Pyrolysis of the enamino esters (1 a, b) leads to the (allylimino)keten intermediates (2 a, b) which by cycloaddition and 1,5-sigmatropic hydrogen shift are converted into the new bicyclic heterocycles (3 a, b), respectively, and, via the azatrienals (5), to the formylpyridines (6 a, b).