Enyne ring-closing metathesis on heteroaromatic cations

Cationic heteroaromatic enynes have been employed as substrates in enyne ring-closing metathesis, under an atmosphere of ethylene and using the Hoveyda-Grubbs catalyst, for the first time; the reaction affords new 1-vinyl- and 2-vinyl-substituted 3,4-dihydroquinolizinium salts, useful precursors for biologically relevant cations based on the quinolinizium system.