Deoxygenated and alkylated furanoses: Thorpe—Ingold effects on tautomeric equilibria and rates of anomerization
作者:Joseph R. Snyder、Anthony S. Serianni
DOI:10.1016/0008-6215(91)80110-9
日期:1991.3
to significantly affect both the thermodynamics and kinetics of furanose anomerization. Increased substitution enhances the proportion of cyclic forms in solution by stimulating furanose kclose. In contrast, furanose kopen was less affected by the degree of substitution; however, kinetic studies of 2-deoxyfuranose anomerization implicate furanose ring conformation as a potential determinant of kopen
2-脱氧-D-甘油四糖,3-脱氧-DL-甘油四糖,3-脱氧-3,3-二-C-甲基-DL-甘油四糖,3-C-甲基-DL-赤藓糖,已经制备了3-C-甲基-DL-苏糖,2-脱氧-5-O-甲基-D-赤戊糖和3-脱氧-5-O-甲基-D-赤戊糖。 -在异头碳上被取代,并通过1H-(300和620 MHz)和13C-nmr(75 MHz)光谱表征。在水溶液(2H2O)中确定环状(α和β呋喃糖酶)和非环状(醛和水合物)形式的比例,并通过1H和13C饱和度测量开环(kopen)和开环(kclose)速率常数。 -转移NMR光谱在p2H 5.0(乙酸缓冲液)和60度下进行。发现呋喃糖环取代的程度显着影响呋喃糖异构化的热力学和动力学。通过刺激呋喃糖闭合,增加的取代增加了溶液中环状形式的比例。相比之下,呋喃糖kopen受取代度的影响较小。然而,对2-脱氧呋喃糖进行异构化反应的动力学研究表明,呋喃糖环的构象可能是kopen的潜在决定因素。