Alkyl enzymatic synthesis

Table 7.3 Repeated alkyl fS-D-glucoside use 7.3 Facile Synthesis of Alkyl P-o-Glucopyranosides 237 ofP. dulcis kernel meal in the enzymatic synthesis of ... 

Thymine derivatives - 5-[7V-(2-Amino-4-hydroxy-6-methyl-5-pyrimidinyl-propyl)-p-carboxyanilinomethyl] uracil (XXXIII) was synthesized for study as a possible intermediate in the enzymatic synthesis of thymidylate. It is active as an enzyme inhibitor against thymidylate synthetase isolated from E. coli [298]. Certain thymine derivatives containing a 2-thioimidazole moiety (XXXIV, R = alkyl) inhibit growth of Ehrlich ascites carcinoma (fluid form) in mice [299]. 

In principle, the use of amino acid or peptide esters as nucleophilic components in protease-catalyzed synthesis is possible, but with a drastically decreased efficiency. However, acyl transfer to arginine or lysine alkyl esters in ice using a-chymotrypsin with regard to its strong preference for basic residues in the P/ position enabled synthesis of a N-protected tripeptide ester in high yield (Scheme 7, see Section 4.2.1.2.2). Furthermore, it was found to be the method of choice in synthesizing new potential protease substrates (for proteases with a preference for basic residues in the Pj position). Neither enzymatic synthesis at room temperature nor synthesis in organic solvents has been shown to proceed in a successful manner. 

The work from Sheldon s group [10] was the first to present the use of ionic liquids in the enzymatic synthesis of esters. Since then, there have been many reports on biosynthesis of esters in ionic liquids. De los Rios et al. [64,65] synthesised a wide range of aliphatic organic esters, commonly used in the perfumery, flavour and pharmaceutical industries, by transesteriflcation from vinyl esters and alcohols catalysed by free CaLB in different 1,3-dialkylimidazolium-based ILs (Fig. 7.2). They analysed the effects of the alkyl chain lengths of the acyl donor and the alcohol. The optimum (C6 for acyl donor and C4 for alcohol) chain lengths were found because the activity decreased with further increase in alkyl chain length. The authors attributed the enzyme behaviour to a substrate modulation mainly due to the different affinity of the lipase towards the different substrates and steric hindrance and denaturalisation by small alcohol molecules. 

Wykle, R. L., Malone, B Snyder, F. (1980). Enzymatic synthesis of l-alkyl-2-acetyl-sn-glycero-3-phosphocholine, a hypotensive and platelet aggregating lipid. J. Biol. Chem. 255, 10256-10260. 

Particles of the enzymatically synthesized phenolic polymers were also formed by reverse micellar polymerization. A thiol-containing polymer was synthesized by peroxidase-catalyzed copolymerization of p-hydroxythiophenol and p-ethylphenol in reverse micelles [70], CdS nanoparticles were attached to the copolymer to give polymer-CdS nanocomposites. The reverse micellar system was also effective for the enzymatic synthesis of poly(2-naphthol) consisting of qui-nonoid structure [71], which showed a fluorescence characteristic of the naphthol chromophore. Amphiphilic higher alkyl ester derivatives were enzymatically polymerized in a micellar solution to give surface-active polymers at the air-water interface [72, 73]. 

Amino Acids and Peptides. - Wasserman s method of one-carbon homologation of carboxylic acids to give a-ketocarboxylates involves reaction with cyanomethylenetriphenyl-phosphorane followed by ozone (Scheme 24) and has been used as a key step in a chemo-enzymatic synthesis of isotopically labelled L-valine, L-isoleucine, and o/fo-isoleucine. Alkylation of the carbanion derived from the imino-substituted methylphosphonate diphenyl ester (186) with indol-3-ylmethyl bromide followed by appropriate deprotection has been used to prepare the phosphonate analogue (187) of tryptophan (Scheme 25). The deprotected analogue (188) and derived peptides show activity as inhibitors of chymotrypsin. Two approaches to solid phase Wadsworth-Enunons reactions which have applications in combinatorial chemistry have been reported. In one diethylphosphonoacetamide is bound to PEG-PAL resin via a peptide link, while... 

Enzymatic Synthesis of Alkyl Glycosides with Ionic Liquid as a Modulator... 

Figures. The methods for preparation of peptide aldehydes. Methods 1 and 2 prepare an N-terminal aldehyde peptide by oxidation of an N-terminal Ser-peptide or hydrolysis of a dimethoxyacetate-peptide. Methods 3-7 prepare C-terminal aldehyde peptides. Methods 3 and 4 are known as the n + 1 method. The peptide alkyl ester or alkyl thioester is obtained from different types of resins then a masked amino acid glycodiol ester is introduced by enzymatic synthesis (3a, 3b) or by a chemical method (4) finally, the peptide is treated with TFA to give the aldehyde peptide. In methods 5 and 6, aldehyde peptides are obtained from oxidation of a peptide glycol diol ester. In method 7, treatment of an N-protected peptide thioester resin with Pd" and EtjSIH gives the cleaved C-terminal peptide aldehyde.

Figure 8.6 Enzymatic synthesis of amino acid-based surfactants (I) linear, (II) dimeric or gemini and (III) diacylglycerol amino acid conjugates. The amino acid can be coupled to an alkyl chain via an ester or an amide linkage.

Enzymatic acylation reactions offer considerable promise in the synthesis of specific ester derivatives of sucrose. For example, reaction of sucrose with an activated alkyl ester in /V, /V- dim ethyl form am i de in the presence of subtilisin gave 1 -0-butyrylsucrose, which on further treatment with an activated fatty acid ester in acetone in the presence of Hpase C. viscosum produced the 1, 6-diester derivative (71,72). 

Lu, W.-Y., Lin, G.-Q., Yu, H.-L. et al. (2007) Facile synthesis of alkyl p-D-glucopyranosides from D-glucose and the corresponding alcohols using fruit seed meals. Journal of Molecular Catalysis B Enzymatic, 44, 72-77. 

Martearena, M. R., Blanco, S. and Ellenrieder, G. (2003). Synthesis of alkyl-alpha-L-rhamnosides by water soluble alcohols enzymatic glycosylation. Bioresource Technology 90 297-303. 

Chiral butenolides are valuable synthons towards y-butyrolactone natural products [37] and have also been successfully applied to the synthesis of paraconic acids. The lactone 91, readily available from the hydroxyamide (rac)-90 by enzymatic resolution [38] followed by iodolactonization, proved to be an especially versatile key intermediate. Copper(I)-catalyzed cross coupling reactions with Grignard reagents allowed the direct introduction of alkyl side chains, as depicted in 92a and 92b (Scheme 13) [39, 40]. Further... 

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