Efficient stereo- and regioselective hydroxylation of alkanes catalysed by a bulky polyoxometalate
Efficient stereo- and regioselective hydroxylation of alkanes catalysed by a bulky polyoxometalate
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DOI：
10.1038/nchem.648
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发表时间：
2010-06-01
期刊：
影响因子：
21.8
通讯作者：
Mizuno, Noritaka
中科院分区：
文献类型：
--
作者：
Kamata, Keigo;Yonehara, Kazuhiro;Mizuno, Noritaka
在温和条件下通过C-H键氧化形成醇的烷烃的直接官能化是合成化学的挑战。大多数烷烃含有大量的C-H键，这给选择性带来困难，并且所使用的氧化剂经常导致过度氧化。在这里，我们描述了一种二钒取代的磷钨酸盐，催化的立体和区域选择性的羟基化烷烃与过氧化氢作为唯一的氧化剂。环状和无环烷烃都被氧化形成醇，选择性大于96%。催化剂的大体积聚氧乙烯酸盐框架导致不寻常的选择性，其可导致仲C-H键而不是较弱的叔C-H键的氧化。该催化剂还避免了化学计量的氧化剂的浪费性分解，其可导致羟基自由基的产生并导致所需产物的非选择性氧化和过氧化。
Direct functionalization of alkanes by oxidation of C-H bonds to form alcohols under mild conditions is a challenge for synthetic chemistry. Most alkanes contain a large number of C-H bonds that present difficulties for selectivity, and the oxidants employed often result in overoxidation. Here we describe a divanadium-substituted phosphotungstate that catalyses the stereo- and regioselective hydroxylation of alkanes with hydrogen peroxide as the sole oxidant. Both cyclic and acyclic alkanes were oxidized to form alcohols with greater than 96% selectivity. The bulky polyoxometalate framework of the catalyst results in an unusual selectivity that can lead to the oxidation of secondary rather than the weaker tertiary C-H bonds. The catalyst also avoids wasteful decomposition of the stoichiometric oxidant, which can result in the production of hydroxyl radicals and lead to non-selective oxidation and overoxidation of the desired products.