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

Abstract

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