Studies on the mechanism of Mannich reaction involving iminium salt as potential Mannich reagent. III. Furan as pseudo acid component

Structures, heats of formation, and vibrational eigenvalues have been calculated by semiempirical AM 1 quantum mechanical method for the reactants, products, and activated complexes of three Mannich reactions, namely, the reaction between potential Mannich reagent H₂N⁺ = CH₂Cl^? and furan and the conventional Mannich reactions between ammonia, formaldehyde, and furan in neutral and acidic media. It has been found that the Mannich reaction involving the potential Mannich reagent occurs more quickly than do the conventional Mannich reactions in neutral medium; the Mannich reaction in acidic medium proceeds most quickly. The results have been discussed in terms of the orbital match and static electric interaction between some atoms of reactant complexes. © 1995 John Wiley & Sons, Inc.