Base catalyzed intramolecular cyclization of dialkycrotyl(3-alkenylpropyn-2-yl)ammonium salts and aqueous base fission of 2,2-dialkyl-4-methyl-and 2,2-dialkyl-4,6-dimethyl-2,6,7,7a-tetrahydro-1H-isoindolium bromides

Cyclization of dimethylcrotyl(3-vinyl-or-3-isopropenylpropyn-2-yl)ammonium bromides in the presence of base gave a mixture of the isomeric 2,2-dialkyl-4-methyl-and 2,2-dialkyl-4,6-dimethyl-2,6,7,7a-tetrahydro-1H-isoindolium bromides. Basic fission of the salts obtained at increased temperature gave a mixture of the isomeric N,N-disubstituted di-and trimethylbenzylamines whose structures were confirmed by their IR, ¹H NMR, and ¹³C NMR spectra.