A mechanistic study for efficient CO2 coupling with epoxides to yield the corresponding carbonates catalyzed by zinc ascorbate under ambient conditions under external additive-free conditions.

We report on the reaction of ethylene-terminated heteroatoms (C 2 X; X = N, O, and S) with CS 2 /CO 2 using Mukaiyama reagent (2-chloro-1-methylpyridinium iodide, CMPI) as a promoter for the preparation of imidazolidin-2-one, oxazolidin-2-one, 1,3-dioxolan-2-one, 1,3-dithiolan-2-one, and their thione counterparts at ambient temperature and pressure. Spectroscopic measurements, viz. , 1 H/ 13 C nuclear magnetic resonance (NMR) and ex situ attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy methods verified the reaction of CS 2 /CO 2 with the ethylene-based substrates and subsequently the formation of cyclic products. The experimental data indicated the formation of the enol -form of imidazolidin-2-one and oxazolidin-2-one, while the keto -form was obtained for their thione correspondents. Furthermore, density functional theory calculations revealed the stability of the keto - over the enol -form for all reactions and pointed out the solvent effect in stabilizing the latter.

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