Ethyl 2-0xo-1, 3, 4-oxathiazole-5-carboxylate (4). A mixture of 99.7 g (0.85 mol) of ethyl oxamate and 552 g (4.23 mol) of chlorocarbonylsulfenyl chloride in toluene was held at reflux for 5.25 h and then was concentrated under vacuum. Benzene was added to the residue, and the solution was extracted twice with water, twice with 5% NaHC03, again with water, and was dried (CaS04) and concentrated under vacuum. The residual oil was ...
