Luu Thi X Thi, Lam Trinh To, Le Thach Ngoc, Duus Fritz
Department of Science, Systems, and Models, Roskilde University, DK-4000, Roskilde, Denmark.
Molecules. 2009 Sep 3;14(9):3411-24. doi: 10.3390/molecules14093411.
Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step "green" reaction pathway based on a solventless alkene group isomerization by KF/Al(2)O(3) to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO(4)/CuSO(4).5H(2)O. The assistance by microwave irradiation results in very short reaction times (<15 minutes). The green conversion of eugenol (4-allyl-2-methoxyphenol) into vanillin (4-hydroxy-3-methoxybenzaldehyde) has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde) by KF/Al(2)O(3) under solvent-free conditions, respectively.
通过基于KF/Al₂O₃的无溶剂烯烃基团异构化形成相应的1-芳基丙烯，以及随后通过KMnO₄/CuSO₄·5H₂O将后者无溶剂氧化为相应苯甲醛的两步“绿色”反应途径，来自[具体来源未提及]的香精油烯丙基苯已快速有效地转化为相应的苯甲醛，产率良好。微波辐射的辅助使得反应时间非常短（<15分钟）。丁香酚（4-烯丙基-2-甲氧基苯酚）向香草醛（4-羟基-3-甲氧基苯甲醛）的绿色转化也以类似方式进行，不过在氧化反应之前需要另外两个微波辅助的合成步骤，分别用于羟基的乙酰化，以及在无溶剂条件下通过KF/Al₂O₃对乙酸香草醛（4-乙酰氧基-3-甲氧基苯甲醛）进行最终的脱乙酰化。
