Ethyl hexanoate, enzymatic

Eor example, in the intestinal tract and liver of both humans and animals DEHP is rapidly hydrolyzed by esterases to yield mono-(2-ethylhexyl) phthalate (MEHP) and 2-ethylhexanol [25]. The latter metabolite is subsequently oxidized enzymatically to 2-ethyl hexanoic acid (2-EHXA) [26]. MEHP, 2-hethylhexanol, and/or their metabolites are the immediate inducers of the majority of enzymes known to be affected by exposure of DEHP [27]. Due to the high importance of the primary and secondary PAE metabolites in the human exposure smdies, during the last years a big number of smdies have been conducted to prove that some of them are appropriate biomarkers to calculate human PAE intake [28-30] and that their determination is easier than calculate it through food intake, which are more time consuming and subjects to several error sources. 

Fruity flavor in dairy products is the result of ethyl ester formation, usually catalyzed by esterases from psychrotrophic or lactic acid bacteria. Ester formation by P. fragi involves liberation of butyric and ca-proic acids from the one and three positions of milk triglycerides and the subsequent enzymatic esterification of these fatty acids with ethanol (Hosono et al. 1974 Hosono and Elliott 1974). Consequently, among the esters formed, ethyl butyrate and ethyl hexanoate predominate. Pseudomonas-produced fruity flavor can occur in fluid milk, cottage cheese, and butter. 

Initial scale up of the enzymatic resolution for production of kilogram quantities of (R)-2-amino-2-ethylhexanoic acid was performed in a batch process. The oil of ethyl 2-amino-2-ethyl-hexanoate was suspended in an equal volume of water containing the enzyme. The enantioselective hydrolysis of the ester proceeded at room temperature with titration of the produced acid by NaOH through a pH stat (Figure 6.4). 

The flavour of distillates from apple and pear is characterised by typical aroma compounds from these fruits formed by enzymatic degradation of fatty acids to C6-fragments like hexanol, trans-2-hexenol, as well as ethyl esters and acetates of hexanoic acid. In distillates of pears, especially of the variety Bartlett pear, the characteristic pear flavour is mainly dominated by the ethyl and methyl esters of frans-2-czs-4-decadienoic acid and trans-2-trans-A-decadienoic acid [27-29], The biogenesis of these monounsaturated, diunsaturated, and triunsaturated esters may be explained by -oxidation of unsaturated linoleic and linolenic acid in the fruits. The sesquiterpene compound a-farnesene, which is formed during postharvest ripening and storage of Bartlett pears [28], shows that quality and intensity of distilled pear spirits is mainly influenced by the quality and degree of ripeness of the fruits. 

ENZYMATIC SYNTHESIS OF ETHYL (3/ ,5S)-DIHYDROXY-6-(BENZYLOXY) HEXANOATE... 

Figure 18.13. Enzymatic synthesis of ethyl (31 ,55)-dihydroxy-6-(benzyloxy)hexanoate (40a).

To determine the stereoselectivity of diastereotopic proton abstraction from the Pro-R methylene group of ACPC (9) in the fragmentation (occurring between Pro-S p-C and a-C), 2-ethyl-[3-Di]-ACPC (8a) was prepared with the ethyl side chain and deuterium substituent in cis relationship. Incubation of this compound followed by in situ reductive enzymatic trapping with (25)-lactate dehydrogenase yielded 2-hydroxy-[3-D]-hexanoate where the R,5-placement of D was analyzed by NMR and the D-content by mass spectrometry. These results had defined the stereoselectivity for )5-H-abstraction from the Pro-R methylene of 2-ethyl-ACPC (8) as the proton removal in the overall fragmentation process and by analogy the same in ACPC (9). These results place stereochemical constraints on the ACPC deaminase process and were accommodated in Scheme 10. 

FIGURE 16.17 Anticholesterol drug 64. Diastereoselective enzymatic reduction of 3,5-dioxo-6-(benzyloxy) hexanoic acid, ethyl ester 62. 

Cholesterol-Lowering Agents Enzymatic Preparation of Ethyl (3S,5R)-dihydroxy-6-(benzyloxy)hexanoate 72... 

Pregabalin enzymatic synthesis of ethyl (S)-3-cyano-5-methyl-hexanoate. 

CHOLESTEROL-LOWERING AGENTS ENZYMATIC SYNTHESIS OF (3S,5/ )-DIHYDROXY-6-(BENZYLOXY) HEXANOIC ACID, ETHYL ESTER... 

Cholesterol-lowering agents enzymatic synthesis of (3S,5/ )-dihydroxy-6-(benzyloxy)hexanoic acid, ethyl ester. 

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