Phosphotungstic Acid as a Versatile Catalyst for the Synthesis of Fragrance Compounds by α‐Pinene Oxide Isomerization: Solvent‐Induced Chemoselectivity
作者:Kelly A. da Silva Rocha、Juliana L. Hoehne、Elena V. Gusevskaya
DOI:10.1002/chem.200800184
日期:2008.7.7
remarkable effect of the solvent on the catalytic performance of H3PW12O40, the strongest heteropoly acid in the Keggin series, allows direction of the transformations of alpha-pinene oxide (1) to either campholenic aldehyde (2), trans-carveol (3), trans-sobrerol (4 a), or pinol (5). Each of these expensive fragrance compounds was obtained in good to excellent yields by using an appropriate solvent. Solvent
溶剂对H3PW12O40(Keggin系列中最强的杂多酸)的催化性能产生了显着影响,使α-pine烯氧化物(1)转变为樟脑醛(2),反式香芹酚(3),反式Sobrerol(4 a)或pinol(5)。这些昂贵的香料化合物中的每一种均通过使用适当的溶剂以良好至极好的收率获得。溶剂的极性和碱性强烈影响反应路径:非极性非碱性溶剂有利于醛2的形成;极性碱性溶剂有利于醇3的形成;在极性弱碱性溶剂中,主要产物是化合物4a和5。另一方面,在非极性碱性溶剂1,4-二恶烷中,醛2和醇3的生成量相当。使用极低的催化剂负载量(0。这种简单,对环境无害且低成本的方法的显着优点是具有005-1 mol%的摩尔浓度以及无需中和就可以回收和回收催化剂的显着优势。该方法代表了由α-hole烯氧化物(除樟脑醛以外)合成异构体的第一个实例,其选择性足以满足实际应用。