Structure of N-acetoxy-N-benzyloxyurea

The crystal structure of N-acetoxy-N-benzyloxyurea has been studied by single crystal X-ray diffraction study. It has demonstrated that this compound is a typical anomeric amide. ON(1)O nitrogen atom has a pyramidal configuration; the sum of the bond angles centered on N(1) atom is 335.20 and this atom is sp3 hybridized. The N(2) nitrogen atom of the carbamoyl moiety (H2NC=O) has planar configuration. The N–OAc bond is somewhat elongated and the N–OBn bond is shortened due to the action of nO(Bn)*N–OAc anomeric effect. In the molecule of N-acetoxy-N-benzyloxyurea, the N–C amide bonds are nonequivalent, and the (AcO)(BnO)N–C(O) bond is longer that the H2N–C(O) bond. Evidently, that this difference in bond lengths is caused by the stronger conjugation between lone pair (Lp) of the N(2) atom and the C=O carbonyl compared to conjugation between the lone pair of N(1) atom and the C=O carbonyl. The overall analysis of the structural parameters on all known N-acyloxy-N-alkoxyureas had been done. In addition, the structural parameters of N-acetoxy-N-benzyloxyurea have been compared with the same structural parameters of N-benzyloxyurea and N-benzyloxy-N-methoxyurea.