Nucleophilic substitution of a phthalimidyl group with morpholine in an N1-methyl-1,2,3-triazole: crystallographic evidence for migration of the methylene bridge.

2-{[4-(4-Bromophenyl)-1H-1,2,3-triazol-1-yl]methyl}phthalimide, C17H11BrN4O, was synthesized by click chemistry employing a copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition. The molecule adopts an angular structure and was found to crystallize in the monoclinic system (space group P21/n, Z = 4). Reaction with morpholine in the presence of a base afforded 4-{[4-(4-bromophenyl)-2H-1,2,3-triazol-2-yl]methyl}morpholine, C13H15BrN4O, as the major product, involving a nucleophilic substitution of morpholine for the phthalimide group and migration of the substituent from N1 to N2 on the 1,2,3-triazole ring. The morpholine-substituted compound likewise crystallizes in the monoclinic system (space group P21/c, Z = 4) with the molecule exhibiting an angular shape. Both crystal structures appear to be governed by close packing, with weak C-H...O and C-H...N hydrogen bonds as the prevailing intermolecular interactions.