Alcohols enzymatic oxidation

Enzymatic oxidations have been reported. Bacilus stearothermophilus, for example, oxidizes secondary alcohols to the ketone. 

As described above, the enzymatic polymerization of phenols was often carried out in a mixture of a water-miscible organic solvent and a buffer. By adding 2,6-di-0-methyl-(3-cyclodextrin (DM-(3-CD), the enzymatic polymerization of water-insoluble m-substituted phenols proceeded in buffer. The water-soluble complex of the monomer and DM-(3-CD was formed and was polymerized by HRP to give a soluble polymer. In the case of phenol, the polymerization took place in the presence of 2,6-di-O-methyl-a-cyclodextrin (DM-a-CD) in a buffer. Only a catalytic amount of DM-a-CD was necessary to induce the polymerization efficiently. Coniferyl alcohol was oxidatively polymerized in the presence of a-CD in an aqueous solution. ... 

Lignin polymerization is a natural process initiated by the enzymatic oxidation of hydroxycinnamyl alcohols such as /)-coumaryl (CM), coniferyl (CF), and sinapyl alcohols (SN), which are known as monolignols (Scheme 2.20).60... 

Alcohols have been converted into aldehydes mediated by a lipophilic / -cyclodextrin bearing a ferrocene moiety [139]. Efficient indirect in situ electroregeneration of NAD+ and NADP+ for enzymatic oxidations of butanol and 2-hexen-l-ol leading to the corresponding aldehydes using Fe bipyridine and phenanthroline complexes as redox... 

Sakai K, Hamada N, Watanabe Y (1984) Non-enzymatic degradation of secondary alcohol oxidase-oxidized poIy(vinyI alcohol). Agric Biol Chem 48 1093-1095... 

An example of a structural substituent that is often metabolized (bioactivated) to an electrophile is the allyl alcohol substituent (C=C—C—OH). Allyl alcohol moieties are found in many commercial chemical substances, either as the free alcohol or as an ester or ether. As illustrated in Scheme 4.1, allyl alcohols (and also as their esters or ethers) that contain at least one hydrogen atom on the alcoholic carbon can be oxidized in the liver by alcohol dehydrogenase (ALDH) to the corresponding a, 3-unsaturated carbonyl metabolite, which is toxic in many cases [29-31]. The hepatotoxicity of allyl alcohol (1), for example, is due to its oxidation by ALDH to acrolein (2), an a,(3-unsaturated aldehyde, which undergoes Michael addition with cellular nucleophiles in the liver [29] (Scheme 4.1). Cyclic allyl alcohols (Scheme 4.1) are expected to undergo similar enzymatic oxidation to yield a,(3-unsaturatcd carbonyl metabolites and are also likely to be toxic. 

As with allyl alcoholic substituents, propargyl alcoholic substituents that contain at least one hydrogen atom on the alcoholic carbon are also known to undergo enzymatic oxidation to the corresponding a,(3-unsaturated carbonyl metabolites and are fairly toxic [30, 31, 34]. In addition, propargyl alcohols that contain an aromatic... 

Popular oxidation reactions of peptide alcohols such as the Parikh-Doering or Dess-Martin in addition to older oxidation reactions such as Collins, pyridinium chlorochromate, or Swern oxidation afford racemization free productsJ9121415 37-39 Oxidations using pyridinium dichromate results in racemization and low yields of product.[l3 Oxidation reactions have also been utilized in semisynthetic pathways of peptide aldehydes (1) peptide aldehydes are obtained through the enzymatic acylation of a peptide ester to an amino alcohol with subsequent oxidation of the peptide alcohol to afford the aldehyde, and (2) peptide aldehydes can also be obtained by direct enzymatic oxidation of the peptide alcohol by alcohol de-hydrogenaseJ40 41 ... 

Semisynthetic enzymatic oxidation of peptide alcohols employs equine liver alcohol dehydrogenase. Amino alcohols with nonpolar side chains and Z-Om[CH2OH] worked as effective substrates while polar amino alcohols such as H-Arg[CH2OH] and H-Lys[CH2OH] failed as substrates. To attain complete oxidation, semicarbazide was present in the reaction mixture to immediately trap the aldehyde, and flavin mononucleotide was used to oxidize the NADH to NAD+, which serves to oxidize the alcohol 41] Configurational stability was confirmed by NMR spectroscopy as in the case of Ac-Phe[CH2OH], which was prepared by sodium borohydride reduction of Ac-Phe-H 4 1... 

In order to assess the synthetic potential of enzymatic oxidations for organosilicon chemistry, the (hydroxyalkyl)silanes 95, 97 and 99 have been studied for their oxidation (dehydrogenation) with horse liver alcohol dehydrogenase (HLADH E.C. l.l.l.l)79. For this purpose, these compounds were incubated with HLADH in a TRIS-HC1 buffer/THF system in the presence of NAD+. As monitored spectrophotometrically (increase of absorbance of the NADH formed), the (2-hydroxyethyl)silane 97 and the (3-hydroxypropyl)silane 99 were better substrates for HLADH than ethanol, whereas the related (hydroxymethyl)silane 95 was not a substrate under the experimental conditions used. Interestingly, the corresponding carbon analogue 101 was found to be accepted by HLADH. On the other hand, the (2-hydroxyethyl)silane 97 was found to be a better... 

The biosynthesis of many bis-indole alkaloids has been postulated to proceed by dimerisation of appropriate precursors, and there is now a substantial amount of experimental evidence to support this hypothesis. For example, treatment of the alcohol 1 with acid gives the alkaloid yuehchukene 2, and 1 could arise biogenetically by in vivo prenylation of indole followed by enzymatic oxidation. A study of related 2-prenylated indoles has confirmed the ease with which such molecules can "dimerise". Thus, treatment of the secondary alcohol 3 in benzene with silica gel impregnated with TsOH gave a complex mixture of products from which 4 (5.1%) and 5 (2.1%) were isolated (3 is very sensitive to acid, and is easily decomposed). Treatment of the isomeric tertiary alcohol 6 with a catalytic amount of TFA in anhydrous benzene gave much higher yields of the two "dimeric" products 7 (31%) and 8 (25%). 

Fig, 3,8 Enzymatic oxidation of ethanol to acetaldehyde [40]. ADH = alcohol dehydrogenase, NAD+ and FMN = cofactors, catalase = second enzyme to regenerate cofactors... 

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