Abstract The synthesis of methyl N -(4-nitrophenyl)-3-oxomorpholine-2-carboxylate and ethyl N -(4-nitrophenyl)-2-oxomorpholine-3-carboxylate, via rhodium(II) acetate catalyzed intermolecular O–H and intramolecular N–H carbene insertion, is described. The products represent new and versatile building blocks for the synthesis of bioactive compounds of pharmaceutical interest.