Factors Affecting Conformation of ( R,R )-Tartaric Acid Ester, Amide and Nitrile Derivatives. X-Ray Diffraction, Circular Dichroism, Nuclear Magnetic Resonance and Ab Initio Studies
作者:Jacek Gawroński、Krystyna Gawrońska、Pawel Skowronek、Urszula Rychlewska、Beata Warżajtis、Jacek Rychlewski、Marcin Hoffmann、Agnieszka Szarecka
DOI:10.1016/s0040-4020(97)00271-8
日期:1997.4
R)-tartaric acid (1a) with all combinations of methyl ester, amide, N-methylamide and N,N-dimethylamide groups, as well as the corresponding O,O′-dibenzoyl derivatives 1b–15b and nitriles 16–18 have been synthesized. Their conformations have been studied by the NMR and CD methods in solution as well as by X-ray diffraction in the crystalline state. The preference for planar. T conformation of the four
衍生物2A-15A(的R,R) -酒石酸(1A)与甲基酯,酰胺,的所有组合ñ -甲基酰胺和Ñ,Ñ -dimethylamide基团,以及相应的ø,ö '二苯甲酰衍生物1B-已经合成了15b和16-18腈。它们的构象已通过NMR和CD方法在溶液中以及通过结晶状态下的X射线衍射进行了研究。对平面的偏爱。Ť在限制α-羟酸,酯或酰胺基团几乎为平面的条件下观察到四个碳链的构象,该构象通过S(5)基序和静电CO / C(β)H的分子内氢键得以稳定和CN / C(β)H共面键相互作用。C = O / C(α)-O键系统倾向于是同平面的(酯,酸)或反平面的(酯,伯和仲酰胺)。从头算就可以证明,对于二酰胺10a和15a的分离分子,强烈要求使用Gauche G + (a,a)构象,驱动力是形成氢键的S(6)主题的氢键六元环的连接,分子的两个不同半部连接OH和C = O。结果与在非极性溶剂中从15a的NMR光谱