Trialkylamine-mediated intramolecular cyclization of pent-4-enoyl chlorides was studied. Substitution with a tertiary alkyl group at the 2-position gave cyclopent-2-en-1-ones, while substitution with an aromatic group gave enol esters, which were formed by O-acylation of initially formed 3-chlorocyclopentanones with ketenes.
