The aza Curtius rearrangement

On interaction of N-(trifluoromethylsulfonyl)carboximidoyl chloirdes in whi ch the carbonyl oxygen atom is substituted by the more strongly electrom-wi thdrawing =NSO2CF3 group) with sodium azide in glyme or acetonile at -5 to +10 degreesC, dinitrogen is eliminated quantitatively and carbodiimides RN= C=NSO2CF3 are formed in high yield. In other words, an aza Curtius rearrang ements occurs. The carbodiimides react with water, alcohols, and secondary amines to give corresponding ureas, isoureas, and guanidine derivatives. Im idoyl chlorides with substituents other than SO2RF do not enter into the az a Curtius reaction.