At 170°C and using ionic liquids as solvent and catalyst, primary and secondary aliphatic amines could react with dimethyl carbonate to give alkyl carbamates with good yield. Due to its insolubility, the desired carbamate solid could be recovered by simple filtration from the two-layer mixture of dimethyl carbonate and ionic liquid after reaction and the formation of N-methylated and deammoniated products were restrained.

★★★★☆ T. Sima et al. / Tetrahedron Letters 43 (2002) 8145–8147.