NAD(P)H Models 20

Ethyl 2-oxo-4-aryl-3-butene-1-oates 1a–1c are reduced by NAD(P)H models (1-n-propyl-1,4-dihydronicotinamide (4) and Hantzsch ester(5)), in presence of magnesium perchlorate. One equivalent of the reductant reduces the substrates selectively to the corresponding 2-oxo-4-arylbutanoates (6,10a,b). An additional equivalent and higher temperature, converts ethyl 2-oxo-4-phenylbutanoate (6) to ethyl 2-hydroxy-4-phenylbutanoate (7). Reduction of ethyl 2-oxo-4-phenyl-3-buten-1-oate (1a) by Hantzsch ester in C2H5OD or by Hantzsch ester-4,4-d2 in C2H5OH, leads to direct transfer of the hydrogen or deuterium, respectively, without isotopic scrambling. These results have been interpreted to support the hydride transfer mechanism.