Ethyl 2-ethenyl-6,7-methylenedioxy-1,2,3,4,-tetrahydro-1-(3′,4′,5′-trimethoxyphenyl)-4-oxoquinoline-3-carboxylate 1 was prepared by the reaction of vinylcuprate on ethyl 1,4-dihydro-6,7-methylenedioxy-1-(3′,4′,5′-trimethoxyphenyl)-4-oxoquinoline-3-carboxylate 9. Different quinolones and a tetrahydro-4-oxoquinoline have been obtained by oxidation of 1. Depending on the reagent, the initial addition