A short and practically convenient, modular approach to hitherto unknown dehydromorpholine sulfones and sulfonamides from α-acyl-α-diazomethyl sulfones and sulfonamides, respectively, has been developed. It involves Rh(II) carbene insertion into the O–H bond of 2-bromoethanol followed by thermally promoted tandem S_N2 displacement of the bromine atom by a primary amine and cyclodehydration.