Analysis of the conformational preferences of (4R,5R)-4,5-bis(alkylcarbamoyl)-1,3-dioxolanes

The conformational preferences of several 4,5-bis(alkylcarbamoyl)-1,3-dioxolanes in R,R configuration were examined by FT-IR, H-1-NMR, C-13-NMR and computational methodologies. On the other hand, both the coupling of the C-13 satellite signals of dioxolane methine protons observed in H-1-NMR spectra and the (3)J(CH) coupling constants in the C-O-C-H segments observed in C-13-NMR were consistent with the two low energy conformations derived from quantum mechanical calculations. These preferred conformations were envelope forms predicted to be approximate to 3.5 - 4 kcal/mol more stable than the twist forms. Copyright (C) 1996 Elsevier Science Ltd