preparation of methyl 5α-methyl-α-d-glucopyranoside and of 5α-fluoro-β-d-glucopyranose per acetate and the NMR-based conformational analysis of their side chains. Both the 5α-methyl and 5α-fluoro substituents increase the population of the gauche,gauche side chain conformer to the extent that it becomes the predominant conformation. In the 5α-methyl series this is attributed to steric effects, whereas in
我们描述了甲基 5α-甲基-α-d-
吡喃
葡萄糖苷和 5α-
氟代-β-d-
吡喃
葡萄糖的制备方法以及基于 NMR 的侧链构象分析。5α-甲基和 5α-
氟取代基都增加了 gauche、gauche 侧链构象异构体的数量,使其成为主要构象。在 5α-甲基系列中,这归因于空间效应,而在 5α-
氟系列中,有吸引力的左旋效应的优化是更可能的原因。