Study of the mechanism of the hydride transfer with a highly reactive and stereoselective NADH model

Abstract

The 1H and 13C NMR spectra of the chiral NADH models 3 and 4 were studied both in the presence or absence of Mg 2+ ions. These two compounds have a chiral carboxamide part derived from (S)-phenylalaninol but contrary to 3, compound 4 has the ability to free-rotate about the C 3CO bond. Careful analysis of the spectral results and comparison with some other studies recently published in the literature allowed the following assumptions: 1-the 1,4-dihydropyridine structure is planar both in the absence or presence of magnesium ions. 2-in the case of the rigid model 3, the CO is out of the plane of the dihydropyridine structure. 3-with Mg 2+ the chiral amino alcohol moiety adopts a quasi-cyclic conformation in the case of 4 but not in the case of 3. The observed enantioselectivities are explained by the mean of ternary complexes between the model, Mg 2+ and the substrate.