Refluxing 3-(2-azidoethyl)-3-[3, 4-(methylenedioxy) phenyl] cyclohex-1-ene (2) in toluene for 24 hours afforded 3a-[3, 4-methylenedioxy) phenyl]-3, 3a, 4, 5, 6, 7-hexahydro-2H-indole (12) in quantitative yield. This reaction proceeds by intramolecular 1, 3-dipolar cycloaddition of the azide onto the alkene followed by loss of nitrogen from the triazoline intermediate to give an imine. Reduction of the imine 12 with sodium cyanoborohydride in acetic acid/THF ...