Vanillyl alcohol

Fraaije MW, WJH van Berkel (1997) Catalytic mechanism of the oxidative demethylation of 4-(methoxymethyl)phenol by vanillyl-alcohol oxidase. Evidence for formation of a /7-quinone intermediate. /Sio/ Chem 272 18111-18116. 

Kondo R, H Yamagami, K Sakai (1993) Xylosation of phenolic hydroxyl groups of the monomeric lignin model compounds 4-methylgnaiacol and vanillyl alcohol by Coriolus versicolor. Appl Environ Microbiol 59 438-441. 

Aryl alcohol oxidase from the ligninolytic fungus Pleurotus eryngii had a strong preference for benzylic and allylic alcohols, showing activity on phenyl-substituted benzyl, cinnamyl, naphthyl and 2,4-hexadien-l-ol [103,104]. Another aryl alcohol oxidase, vanillyl alcohol oxidase (VAO) from the ascomycete Penicillium simplicissimum catalyzed the oxidation of vanillyl alcohol and the demethylation of 4-(methoxymethyl)phenol to vanillin and 4-hydro-xybenzaldehyde. In addition, VAO also catalyzed deamination of vanillyl amine to vanillin, and hydroxylation and dehydrogenation of 4-alkylphenols. For the oxidation of 4-alkylphenol, the ratio between the alcohol and alkene product depended on the length and bulkiness of the alkyl side-chain [105,106]. 4-Ethylphenol and 4-propylphenol, were mainly converted to (R)-l-(4 -hydroxyphenyl) alcohols, whereas medium-chain 4-alkylphenols such as 4-butylphenol were converted to l-(4 -hydroxyphenyl)alkenes. 

Van den Heuvel, R.H.H., Laane, C. and van Berkel, W.J.H. (2001) Exploring the biocatalytic potential of vanillyl-alcohol oxidase by site-directed mutagenesis. Advanced Synthesis and Catalysis, 343 (6-7), 515-520. 

Valeraldehyde, p28 Valeric acid, p38 Valeronitrile, p35 Valeryl chloride, p45 Vanillic acid, hi43 Vanillin, hl42 Vanillyl alcohol, hl45 Veratraldehyde, d492 Veratric acid, d496 Veratrole, d493 Veronal, d330... 

TLC analysis of samples was conducted on silica-gel plates carefully spotted with 10-20 pg of standard compounds, and 30 pL of bioconversion reaction samples. Plates developed with 75 25 1 (v/v/v) CH2CI2/CH3CN/HCOOH solvent may be visualized with a 254 nm UV lamp and/or by spraying with a 30 % w/v phosphomolybdic acid/ 95% ethanol spray reagent followed by gentle heating. Rf values of standards are vanillyl alcohol, 0.8 vanillic acid, 0.5 and vanillin 0.4. 

Most of the vanillic acid was reduced by E. coli containing Car in 2 h to vanillin (80 %) and vanillyl alcohol (20 %). Car does not reduce aldehydes to alcohols. However, E. coli s endogenous aldehyde reductase/dehydrogenase reduces vanillin to vanillyl alcohol. The broad substrate specificity of Car enables the wide application of this biocatalyst to other important applications, such as enantiomeric resolution of isomers such as ibuprofen and the reductions of many other natural and synthetic carboxylic acids. 

Spillman, P.J., Pollnitz, A.P., Eiacopoulos, D., Pardon, K.H., and Sefton, M.A. Formation and degradation of furfuryl alcohol, 5-methylfurfuryl alcohol, vanillyl alcohol and their ethyl ethers in barrel-aged wines, / Agric. Food CAe/n., 46 (2) 657-663, 1998. 

In flavin-dependent monooxygenases, a flavin-oxygen intermediate reacts with the substrate, also producing water in a second step, and requiring cofactors for regeneration of the flavin moiety. The unusual flavoprotein vanillyl-alcohol oxidase (EC 1.1.3.38), in which the flavin moiety is covalently bound, catalyzes the oxidation of p-substituted phenols as well as deamination, hydroxylation and dehydrogenation reactions [10]. 

The arylamine 780c required for the total synthesis of carbazomycin E (264) was prepared in seven steps starting from vanillyl alcohol (803). Vanillyl alcohol (803) was transformed to the tetrasubstituted aryl derivative 804 via generation of the benzyl methyl ether followed by ortho-directed lithiation and subsequent... 

Aromatic Ring Cleavage of Phenolic 0-0-4 Substructure Model Compounds by Laccase. When vanillyl alcohol was used as a substrate, only biphenyl formation (C5-C5 linked) occurred and no evidence for the formation of any ring-opened products was obtained (26). Hence, we also examined the effect of laccase on the sterically hindered 4,6-di-<-butylguaiacol substrate 50, as it would be unlikely to undergo such free-radical coupling reactions... 

Properties. Vanillin is a colorless crystalline solid mp 82-83 °C) with a typical vanilla odor. Because it possesses aldehyde and hydroxyl substituents, it undergoes many reactions. Additional reactions are possible due to the reactivity of the aromatic nucleus. Vanillyl alcohol and 2-methoxy-4-methylphenol are obtained by catalytic hydrogenation vanillic acid derivatives are formed after oxidation and protection of the phenolic hydroxyl group. Since vanillin is a phenol aldehyde, it is stable to autoxidation and does not undergo the Cannizzarro reaction. Numerous derivatives can be prepared by etherification or esterification of the hydroxyl group and by aldol condensation at the aldehyde group. Several of these derivatives are intermediates, for example, in the synthesis of pharmaceuticals. 

Vanilla flavour is not only determined and characterised by the vanillin molecule, but also by many more phenolic compounds and vanillin derivatives. Two examples of molecules that recently obtained FEMA-GRAS status are vanillyl ethyl ether and vanillin 2,3-butanediol acetal (Scheme 13.11). Vanillin can be hydrogenated to form vanillyl alcohol, which is also used in vanilla flavours. Vanillyl alcohol can be reacted with ethanol to form vanillyl ethyl ether. Vanillin can also form an acetal with 2,3-butanediol (obtained by fermentation of sugars) catalysed byp-toluene sulfonic acid in toluene. 

Vanillyl alcohol oxidase (VAO) is a flavoenzyme from the ascomycete Penicil-lium simplicissimum that converts a broad range of 4-hydroxybenzyl alcohols and 4-hydroxybenzylamines into the corresponding aldehydes. This large substrate specificity makes it possible to obtain vanillin from two major pathways. 

As VAO is able to perform an oxidative deamination of capsaicin-derived vanillyl amine, vanillin can be produced by the pathway described in the previous subsection. Van den Heuvel et al. [83] pointed out this biocatalytic route of synthesis in 2001 using penicillin G acylase to obtain vanillyl alcohol from natural capsaicin (Scheme 22.6). As the vanillin obtained can be labelled as natural. 

Scheme 22.6 Oxidative deamination of capsaicin-derived vanillyl amine and formation of vanillin [83] VAO vanillyl alcohol oxidase...

The second pathway using VAO reported by van den Heuvel et al. [83] is the VAO-catalysed oxidation of vanillyl alcohol to vanillin. Vanillyl alcohol is not very abundant in nature but can be generated by VAO-catalysed conversion of creosol (2-methoxy-p-cresol). As creosol can be found in creosote obtained from heating wood or coal tar, the feedstock for this pathway is very abundant. 

The process comprises two steps the conversion of creosol to vanillyl alcohol and the oxidation of the alcohol to vanillin (Scheme 22.7). Interestingly, these two steps are catalysed by the same enzyme, i.e.VAO. 

Yasuda and Terashima (11) recently showed that lignin under Klason lignin determination conditions afforded mefa-linked products. Vanillyl alcohol (4) yielded after reflux in 5% sulfuric acid, mefa-linked product (8) (Fig. 3). 

Figure 2. The reaction of vanillyl alcohol (4) with a reactive phenol (5)-...

Figure 3. Self-condensation of vanillyl alcohol ( 4 ) and 3,4-dimethoxybenzyl alcohol ( 8 ) in acid (11).

Gastrodia elata Blume G. elata Blume f. pallens (Kitag.) Tuyama Tian Ma (root) Vanillyl alcohol, vanilin, vitamin A, gastrodin.33 Anticonvulsive, sedative, analgesic effect. 

In a later paper (7) they discussed the treatment of some lignin model compounds (e.g., vanillic acid and vanillyl alcohol) with sulfite liquors under varying pulping conditions. Their results indicated that pyrocatechol groups may be formed in lignin during semichemical sulfite pulping. 

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