Reaction of methyl bromocycloalkanecarboxylates with zinc and dihydroisoquinoline derivative

The reaction of 5–7-membered methyl 1-bromocycloalkanecarboxylates with zinc and 6,7-dimethoxy-3,4-dihydroisoquinoline leads to 7,8-dimethoxy-5,9b-dihydro-2H,4H-spiro{azeto[2,1-a]isoquinoline-1,1′-cycloalkan}-2-ones. In the case of 1-bromocyclobutanecarboxylate, 9′,10′-dimethoxy-7′,11b′-dihydro-2′H,4′H,6′H-dispiro{cyclobutane-1,1′-pyrido[2,1-a]isoquinoline-3′,1″-cyclobutane}-2′,4′-dione is formed. The structures of the products were confirmed by X-ray diffraction.