The Regiochemistry of the Cycloaddition of 4‐R‐Phenacylpyridazinium Ylides to Nonsymmetrical Substituted Olefins

The regiochemistry of the [3+2] cycloaddition reactions between 4-R-phenacylpyridazinium ylides and acrylonitrile has been studied. Theoretical and experimental studies have been performed, both of which show that the reaction is regiospecific. Four new tetrahydropyrrolopyridazine heterocycles have been obtained. The structures of the new compounds were established by elemental (C,H,N) and spectral analyses (IR, 1H and 13C NMR, MS).