Influence of intramolecular hydrogen-bonding on the conformational properties of sugar thioureas
作者:Carmen Ortiz Mellet、Alberto Moreno Marín、José L. Jiménez Blanco、José M. García Fernández、José Fuentes
DOI:10.1016/s0957-4166(00)80382-1
日期:1994.12
anose with ammonia afforded the conesponding sugar thioureas. Both the Z and E stereoisomers around the NHC(S) bond were observed in the 1H and 13C NMR spectra of the later in the low temperature range, their relative proportions being a function of the sugar configuration. Experimental evidence for the existence of seven-membered NH⋯O intramolecular hydrogen bonds in the E isomers of thioureas has
的1,2- deoxyisothiocyanato衍生物的反应:3,4-二- ö异亚丙基α-d吡喃半乳糖,1,2:3,5-二- ö异亚丙基α-d呋喃葡萄糖,和2,3:带有氨的4,5-二-O-异亚丙基-β-D-果糖基葡萄糖提供了相应的糖硫脲。在低温范围内,后者的1 H和13 C NMR光谱中均观察到NHC(S)键周围的Z和E立体异构体,它们的相对比例是糖构型的函数。E中存在七元NH⋯O分子内氢键的实验证据硫脲的异构体已从DNMR实验,旋转势垒高度计算,NH信号1 H化学位移的温度系数测量以及溶剂极性对旋转比例的影响研究中获得。
Conformational energetics of sugar thioureas and synthesis of glycosyl thioureido sugars
作者:JoséM. García Fernández、Carmen Ortiz Mellet、Víctor M. Díaz Pérez、JoséL. Jiménez Blanco、José Fuentes
DOI:10.1016/0040-4020(96)00673-4
日期:1996.9
of the reaction of 6-deoxy-6-isothiocyanatoaldopyranoside derivatives with ammonia depend strongly on the nature of the hydroxyl protecting groups and solvent. In pyridine as solvent, the expected thioureas are obtained as the sole reaction products. A marked preference for the E configuration at the sugarNHC(S) bond is observed for silylated as compared to acetylated derivatives. Rotational barrier