Fast and green microwave-assisted conversion of essential oil allylbenzenes into the corresponding aldehydes via alkene isomerization and subsequent potassium permanganate promoted oxidative alkene group cleavage.
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.
Department of Science, Systems, and Models, Roskilde University, DK-4000, Roskilde, Denmark. luu@ruc.dk
Thi X Thi
TX
Luu
Trinh To
TT
Lam
Thach Ngoc
TN
Le
Fritz
F
Duus
D000475:Alkenes / Q000737:chemistry*; D000498:Allyl Compounds / Q000737:chemistry*; D001547:Benzaldehydes / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry*; D005054:Eugenol / Q000737:chemistry; D055772:Green Chemistry Technology / Q000379:methods*; D006868:Hydrolysis; D007536:Isomerism; D008872:Microwaves; D009822:Oils, Volatile / Q000737:chemistry*; D010084:Oxidation-Reduction; D011196:Potassium Permanganate / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D000081248:Allylbenzene Derivatives
D000475:Alkenes; D000498:Allyl Compounds; D001547:Benzaldehydes; D001555:Benzene Derivatives; D005054:Eugenol; D009822:Oils, Volatile; D011196:Potassium Permanganate; D012997:Solvents; C102347:allylbenzene; D000081248:Allylbenzene Derivatives; C100058:vanillin