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The regioselectivity of nucleophilic addition of azoles to unsymmetrical fumarates producing the corresponding (+/-)-2-azol-1-ylsuccinates was examined. The main regioisomer was identified as the one derived from the attack of the azole to the more congestive side of the double bond. The results were analyzed in terms of HOMO-LUMO interactions by semiempirical AM1 molecular orbital computations.

Regioselective neutral hydrolysis of 2-imidazol-1-ylsuccinic esters, prepared by the thermal addition of imidazol to fumaric or maleic ester, generates corresponding half-esters of 2-imidazol-1-yl-3-(alkoxy-carbonyl)-propionic acids. NMR spectroscopic studies of the kinetics of hydrolysis using 18O and 17O labeling support the mechanism proposed for hydrolysis. Nature of the alcohol group influences the results of hydrolysis. Hydrolysis of imidazolylsuccinic esters is faster than that of homologous derivatives from pyrazole or benzimidazole.