Concomitant Formation of Isomeric 1-, 2-, and 3-Substituted Heptafulvenes from 2-Substituted Tropones and Active Methylene Compounds

Article abstract of DOI:10.1246/cl.1992.855

Condensations of methyl cyanoacetate and 4-nitrobenzyl cyanide with 2-isopropyl-, 2-methyl-, and 2-phenyltropones in Ac2O gave isomeric 1-, 2-, and 3-substituted heptafulvene derivatives.The mechanism of reaction was explained in terms of a remote nucleophilic attack of the active methylene compounds to acetoxycycloheptatrienylium salt, followed by <1,5> sigmatropic hydrogen shift and elimination of acetic acid.