2-Amino-4-aryl-1-arylideneaminoimidazoles and Acylation Products: A Multinuclear (1H, 13C, 15N) NMR Study
The structure of 2-amino-4-aryl-1-arylideneaminoimidazoles in DMSO-d6 solution was investigated by means of NMR spectroscopic methods (1H, 13C, 15N). From these data the (E)-configuration at the excocyclic C=N bond and a strong preference for the conformer with the imidazole H-5 and the N=CH proton being spatially close (s-trans regarding the N–N bond) can be concluded. Reaction of the title compounds with acetic anhydride leads to mono and diacylation at the 2-amino group, whereas treatment with pivalic anhydride exclusively affords the corresponding monoacyl product. The mono- and diacylation products exhibit similar configurational and conformational properties as the parent compounds.
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