中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
N-苄氧羰基氨基乙腈 | phenylmethyl cyanomethylcarbamate | 3589-41-1 | C10H10N2O2 | 190.202 |
The synthesis and resonance Raman spectra of several new N-acyl glycine ethyl dithioesters RC(=O)NH—CH2—C(=S)SR are reported. The resonance Raman spectra of these compounds contain at least two peaks in the "C=S stretching region" between 1050 and 1200 cm−1. The solvent, concentration, temperature, and excitation wavelength dependencies of these features have been investigated. The results obtained are consistent with two conformations of the dithioesters co-existing in solution with the conformational differences being controlled by rotational isomerism about one or both of the NH—CH2 and CH2—CS bonds. Strong support for the existence of more than one conformer in solution comes from the Raman spectrum of a single crystal of N-acetyl glycine ethyl dithioester. In the spectrum of the single crystal several Raman bands are absent compared to the spectrum of the dithioester in solution indicating that only one of the conformers found in the solution phase is retained in the crystal. In one of the conformers found in solution there is evidence for an intramolecular interaction between the amide group and the dithioester group. The exact nature of the intramolecular interaction is uncertain, although simple H-bonding and enethiol tautomerism have been eliminated as possibilities. Possible contributors to the interaction are dipole–dipole forces and amide π-electrons interacting through space with sulfur dx orbitals. Both of these putative interactions would be modulated by rotational isomerism. Based on deuterium substitution experiments a resonance Raman band is identified in the 1050–1200 cm−1 region which contains a contribution from the motion of the amide proton. The unexpected intensity enhancement of an amide mode is attributed to the amide–dithioester intramolecular interaction. The conformer exhibiting the intramolecular interaction is thought to closely resemble the conformation of the substrate in the active site of certain dithioester enzyme–substrate complexes.