Regioselective Anionic [3+2] Cyclizations of Imidazole Dinucleophiles with Oxaldiimidoyl Dichlorides − A Combined Experimental and Theoretical Study

Regioselective cyclization reactions between oxaldiimidoyl dichlorides and imidazole-derived dinucleophiles provide convenient access to biologically relevant diazabicyclo[2.2.1]heptanones, 1H-pyrrolo[1,2-a]benzimidazoles, 3H-imidazo[1,2-a]benzimidazoles and 2,3-dihydrothiazolo[3,2-a]benzimidazoles. All cyclizations proceed with good regioselectivity, directed by the heteroatoms of the dinucleophile. The tautomeric forms of the structurally mobile benzimidazoles have been studied both in solution and in the solid state. The structural properties and the regioselectivities are explained by semiempirical calculations.