Organic Chemistry, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
Carbohydr Res. 2008 Nov 24;343(17):2997-3000. doi: 10.1016/j.carres.2008.08.022. Epub 2008 Aug 29.
The reaction kinetics for a number of reductive openings of methyl 2,3-di-O-benzyl-4,6-O-benzylidene-alpha-D-glucopyranoside have been investigated. Openings to give free HO-6 (using BH(3) x THF-AlCl(3)-THF or LiAlH(4)-AlCl(3)-Et(2)O) follow first order kinetics, while reactions yielding free HO-4 (using BH(3) x NMe(3)-AlCl(3)-THF or BH(3) x NMe(3)-BF(3) x OEt(2)-THF) follow higher order kinetics. The addition of water to the BH(3) x NMe(3)-AlCl(3)-THF results in faster reactions. The BH(3) x SMe(2)-AlCl(3)-THF system constitutes a borderline case, yielding both free HO-6 (by a first order reaction) and free HO-4 (by a higher order reaction). These results correlate well with the concept of regioselectivity by activation of borane complexes.
已经研究了几种还原开环反应的动力学，这些反应涉及甲基 2,3-二-O-苄基-4,6-O-亚苄基-α-D-吡喃葡萄糖苷。使用 BH(3) x THF-AlCl(3)-THF 或 LiAlH(4)-AlCl(3)-Et(2)O 将其开环生成游离 HO-6 遵循一级动力学，而使用 BH(3) x NMe(3)-AlCl(3)-THF 或 BH(3) x NMe(3)-BF(3) x OEt(2)-THF 将其开环生成游离 HO-4 遵循更高阶动力学。向 BH(3) x NMe(3)-AlCl(3)-THF 中添加水会导致反应加快。BH(3) x SMe(2)-AlCl(3)-THF 体系是一个边界情况，同时生成游离 HO-6（通过一级反应）和游离 HO-4（通过更高阶反应）。这些结果与通过硼烷配合物的区域选择性活化的概念很好地相关。
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