Ogasawara Yoshiyuki, Uchida Sayaka, Yamaguchi Kazuya, Mizuno Noritaka
Department of Applied Chemistry, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Chemistry. 2009;15(17):4343-9. doi: 10.1002/chem.200802536.
The tin-tungsten mixed oxide prepared by the calcination of the tin-tungsten hydroxide precursor with a Sn/W molar ratio of 2 at 800 degrees C (SnW2-800) acts as an effective and reusable solid catalyst for C-C bond-forming reactions, such as the cyclization of citronellal, the Diels-Alder reaction, and the cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (TMSCN). Various kinds of structurally diverse aliphatic, aromatic, and unsaturated, heteroatom-containing substrates could be converted into the desired products in high to excellent yields. The observed catalyses for these reactions were truly heterogeneous and the recovered catalyst could be reused several times without an appreciable loss of its high catalytic performance. The Brønsted acid sites generated on the aggregated polytungstate species on SnW2-800 likely play an important role in the C-C bond-forming reactions.
通过在800℃下煅烧锡钨摩尔比为2的氢氧化锡钨前驱体制备的锡钨混合氧化物（SnW2-800），可作为一种有效且可重复使用的固体催化剂，用于碳-碳键形成反应，如香茅醛的环化反应、狄尔斯-阿尔德反应以及羰基化合物与三甲基硅基氰（TMSCN）的氰基硅烷化反应。各种结构多样的脂肪族、芳香族和不饱和含杂原子底物都能以高至优异的产率转化为所需产物。观察到这些反应的催化作用确实是非均相的，回收的催化剂可重复使用多次，而其高催化性能不会有明显损失。SnW2-800上聚集的多钨酸盐物种上产生的布朗斯特酸位点可能在碳-碳键形成反应中起重要作用。
