investigations indicated that the furanosylation mechanism is shifted toward an SN1 reaction on the mechanistic continuum between the prototypical SN1 and SN2 substitution types, as compared to the pyranosylation reaction inside the same catalyst. This is especially true for the lyxosyl donor, as indicated by the nucleophile reaction order of 0.26, and supported by metadynamics calculations. The mechanistic
间苯二酚[4]芳烃胶囊被发现可催化多种不同呋喃糖基供体的β-选择性呋喃糖基化反应:α- d-和α- l-阿拉伯糖基-、α -l-岩藻糖基-、α -d-核糖基-、 α- d-木糖基-,甚至α- d-来木糖基氟化物。范围仅受封闭胶囊催化剂内部固有的有限体积的限制。该催化剂易于获得100克以上的规模,并且可以回收至少七轮,而不会显着损失活性、产率和选择性。机理研究表明,与同一催化剂内的吡喃基化反应相比,呋喃基化机理在原型S N 1 和S N 2 取代类型之间的机械连续体上转向S N 1 反应。对于来苏糖基供体来说尤其如此,如亲核反应级数 0.26 所示,并得到元动力学计算的支持。向 S N 1 的机械转变备受关注,因为它表明该催化剂不仅能够独立于底物构型进行 β-选择性呋喃糖基化和吡喃糖基化,而且还能够独立于操作机制。据我们所知,没有可替代的催化剂能够显示出这种特性。
Haworth; Westgarth, Journal of the Chemical Society, 1926, p. 886
作者:Haworth、Westgarth
DOI:——
日期:——
Kovac, Chemicke Zvesti, 1971, vol. 25, p. 460
作者:Kovac
DOI:——
日期:——
156. Boric acid derivatives as reagents in carbohydrate chemistry. Part III. The interaction of phenylboronic acid with methyl xylofuranosides and the isolation of the four methyl xylosides
作者:R. J. Ferrier、D. Prasad、A. Rudowski
DOI:10.1039/jr9650000858
日期:——
825. Synthesis of 3 : 4- and 3 : 5-dimethyl xylose