Cyclization of dialkyl(3-phenylpropen-2-yl)-(3-phenylpropyn-2-l)ammonium bromides by the action of an aqueous alkali solution. aqueous-alkaline cleavage of the cyclization products – n,n-dialkyl-4(9)-phenyl-3a,4-dihydro-benzo[f]isoindolinium bromides

When heated in an alkaline aqueous medium, dialkyl(3-phenylpropen-2-yl)(3-phenylpropyn-2-yl)- ammonium bromides undergo intramolecular cyclization, forming N,N-dialkyl-4(9)-phenyl-3a,4-dihydrobenzo[ f ]isoindolinium bromides. The cyclization products undergo aqueous-alkaline cleavage at the C(1)–N(2) or N(2)–C(3) bond, which leads to a mixture of 2-(dialkylaminomethyl)-3-methyl- and 3-(dialkylaminomethyl)-2-methyl-1-phenylnaphthalenes. However, only the C(1)–N(2) bond cleavage product is formed in the case of 2,2-pentamethylene-9-phenyl-3a,4-dihydrobenzo-[f]isoindolinium bromide.