Abstract Starting with chlorosulfonylisocyanate (CSI) two new series of 2-haloethyl carboxysulfamides 5 and 2-haloethyl oxosulfonylureas 6 have been prepared. The haloethyl carboxylate 5 underwent a novel cyclisation in the presence of Et 3 N to furnish quantitative yields of N-substituted oxazolidin-2-ones. This procedure constitutes a new route to these heterocycles.
