棉酚席夫碱：一项核磁共振和密度泛函理论研究。
Schiff bases of gossypol: an NMR and DFT study.
作者信息
That Quang Ton, Nguyen Kim Phi Phung, Hansen Poul Erik
机构信息
University of Natural Sciences, National University of HoChiMinh City, Vietnam.
出版信息
Magn Reson Chem. 2005 Apr;43(4):302-8. doi: 10.1002/mrc.1532.
Schiff bases of gossypol with benzylamine, methylamine, 4-aminoacetophenone and 4-fluoroaniline have been synthesized and characterized by NMR spectroscopy. All the Schiff bases of gossypol are in the enamine form according to (3)J(HC,NH) and (1)J(N,H) coupling constants. The spectra are basically unchanged by change of solvent (CD(2)Cl(2), THF-d(8) and CD(3)OD) and by variation of temperature. For the derivative of benzylamine, deuterium isotope effects on (13)C chemical shifts are determined. They support strongly the enamine form and serve as a reference for other tautomeric Schiff bases. Structures and NMR nuclear shieldings of model compounds (the second monomer is replaced by a 2-hydroxybenzene ring) have been calculated by density functional theory (DFT) methods. A good correlation is observed between calculated (13)C nuclear shieldings of the enamine form and observed (13)C chemical shifts.
已合成棉酚与苄胺、甲胺、4-氨基苯乙酮和4-氟苯胺的席夫碱，并通过核磁共振光谱对其进行了表征。根据（3）J（HC，NH）和（1）J（N，H）耦合常数，所有棉酚的席夫碱均为烯胺形式。光谱基本上不会因溶剂（CD(2)Cl(2)、THF-d(8)和CD(3)OD）的变化以及温度的变化而改变。对于苄胺衍生物，测定了氘同位素对（13）C化学位移的影响。它们有力地支持了烯胺形式，并为其他互变异构席夫碱提供了参考。通过密度泛函理论（DFT）方法计算了模型化合物（第二个单体被2-羟基苯环取代）的结构和核磁共振屏蔽。在烯胺形式的计算（13）C屏蔽与观察到的（13）C化学位移之间观察到良好的相关性。
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