Eco-Efficient Synthesis of Cyclic Carbamates/Dithiocarbonimidates from Cyclic Carbonates/Trithiocarbonate and Aromatic Amines Catalyzed by Ionic Liquid BmimOAc.

We have investigated the reactions of cyclic carbonates/trithiocarbonate and aromatic amines in the presence of a basic ionic liquid, 1-butyl-3-methylimidazolium acetate (BmimOAc), which produced various cyclic carbamates/dithiocarbonimidates in fairly good to excellent yields. The use of BmimOAc as catalyst here not only offers an effective approach to the synthesis of the target compounds, but also avoids the use of conventional toxic materials. By means of the reactions of cyclic carbonates and aromatic amines, 3-aryloxazolidin-2-ones, 3,3′-aryldioxazolidin-2-ones and 3-aryl[1,3]oxazinan-2-ones could be synthesized. NMR spectroscopy and DFT calculations revealed that both the cation and the anion of BmimOAc activate cooperatively the substrates in these reactions by means of inducing hydrogen bonding. In addition, condensation reactions of ethylene trithiocarbonate and aromatic amines also proceeded very well in the presence of the BmimOAc catalyst, which opened a hitherto unreported route to [1,3]dithiolan-2-ylidene-arylamine derivatives in a straightforward way. [ABSTRACT FROM AUTHOR]