The C-4 configuration as a probe for the study of glycosidation reactions
The C-4 configuration as a probe for the study of glycosidation reactions
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DOI：
10.1002/ejoc.200300540
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发表时间：
2004-01-16
影响因子：
2.8
通讯作者：
Bols, M
中科院分区：
文献类型：
--
作者：
Bülow, A;Meyer, T;Bols, M
轴向和赤道OBn的吸电子能力的差异被用作探针来研究糖苷化反应。在一系列涉及催化剂、溶剂和糖基受体变化的糖苷化条件下，比较了全苄基化葡萄糖基和半乳糖基供体的反应性。通常，半乳糖基供体的反应性比葡萄糖基供体高4 - 5倍，这与具有正性的过渡态雅阁。然而，在某些情况下，特别是当存在三氟甲磺酸酯时，发现葡萄糖基和半乳糖基供体的反应性相等。((C)Wiley-VCH Verlag GmbH & Co. KGaA，69451魏因海姆，德国，2004）。
The difference in the electron-withdrawing powers of axial and equatorial OBn was used as a probe to investigate the glycosidation reaction. The reactivity of perbenzylated glucosyl and galactosyl donors were compared under a range of glycosidation conditions that involved variations in catalyst, solvent, and glycosyl acceptor. Generally, the galactosyl donor had a reactivity four to five times higher than the glucosyl donor, which is in accord with the transition state having positive character. In certain cases, however, particularly when triflate was present, equal reactivity of glucosyl and galactosyl donors were found. The results are explained in terms of changes in the rate-determining steps. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).