Butyric acid, 2-Amino-2-ethyl

Amino-4-(ethylmercapto)-butyric acid, S-ethyl-L-homocysteine, homocysteine-S-ethyl ester. 

SYNS AETHIONIN 2-AMINO-4-(ETHYLTHIO)BUTYRIC ACID dl-2-AMINO-4-(ETHYLTHIO)BUTYRIC ACID CN 8676 ETH ETHIONIN ETHIONINE ( )-ETHIONINE S-ETHYL-HOMOCYSTEINE S-ETHYL-dl-HOMOCYSTEINE NSC-751 U-1434... 

ETHATO-7-(2-HYDROXY-3-((l-METHYLETHA L)AMINO)PROPOXY)-4-BENZOFUKANAT) ETHANONE see ELI600 a-ETHYL-p-(HYDROXYMETHYL)-l-METHYL-IMIDAZOLE-5-BUTYRIC ACID, y-LACTONE see PIFOOO... 

The 2-D TLC was successfully applied to the separation of amino acids as early as the beginning of thin-layer chromatography. Separation efficiency is, by far, best with chloroform-methanol-17% ammonium hydroxide (40 40 20, v/v), n-butanol-glacial acetic acid-water (80 20 20, v/v) in combination with phenol-water (75 25, g/g). A novel 2-D TLC method has been elaborated and found suitable for the chromatographic identification of 52 amino acids. This method is based on three 2-D TLC developments on cellulose (CMN 300 50 p) using the same solvent system 1 for the first dimension and three different systems (11-IV) of suitable properties for the second dimension. System 1 n-butanol-acetone -diethylamine-water (10 10 2 5, v/v) system 11 2-propanol-formic acid-water (40 2 10, v/v) system 111 iec-butanol-methyl ethyl ketone-dicyclohexylamine-water (10 10 2 5, v/v) and system IV phenol-water (75 25, g/g) (h- 7.5 mg Na-cyanide) with 3% ammonia. With this technique, all amino acids can be differentiated and characterized by their fixed positions and also by some color reactions. Moreover, the relative merits of cellulose and silica gel are discussed in relation to separation efficiency, reproducibility, and detection sensitivity. Two-dimensional TLC separation of a performic acid oxidized mixture of 20 protein amino acids plus p-alanine and y-amino-n-butyric acid was performed in the first direction with chloroform-methanol-ammonia (17%) (40 40 20, v/v) and in the second direction with phenol-water (75 25, g/g). Detection was performed via ninhydrin reagent spray. 

Synonyms S-Ethyl-u-homocysteine a-Amino- y-(ethylmercapto)butyric acid... 

The hydrogenation of 2,4-diketo acid derivatives to the corresponding 2-hydroxy compounds with cinchona-modified Pt catalysts as depicted in Figure 2.4 can be carried out with chemoselectivities more than 99% and enantioselectivities up to 87% (R) and 68% (S), respectively [30a]. Enrichment to more than 98% ee was possible for several substrates by recrystallization, giving rise to an efficient technical synthesis of (R)-2-hydroxy-4-phenyl butyric acid ethyl ester [30b], a building block for several ACE (angiotensin-converting enzyme) inhibitors, as well as some enantio-merically enriched a-hydroxy and a-amino acid esters (see below) [30c]. 

In a similar manner the other amino acids react tyrosine, j3-p-hydroxy-phenyl-a-amino-butyric acid yielding p-hydroxy-phenyl-ethyl alcohol, tyrosol while phenyl-alanine, a-amino-j8-phenyl-propionic acid, yields phenyl-ethyl alcohol. Succinic acid, for example, which is of usual occurrence in fermented liquors is probably formed by a similar reaction from glutamic acid with the additional step of oxidation in the process. 

The isomers of 4-amino-3-(4-chlorophenyl)butyric acid were separated on a preparative scale using a silica column (A = 260nm) and 80/20 ethyl acetate/ hexane mobile phase [882], Up to 375 mg of sample was injected and baseline resolution was achieved in 6 min. 

A very interesting modification of method B was applied to the stereospecific synthesis of ( )-pseudoheliotridane.27 Condensation of ethyl bromoacetate with l-methyl-2-ethyl-4,5-dihydropyrrole (42) afforded the quaternary salt 43, which was reduced, without isolation, with formic acid to give ethyl /3-(Ar-methyl-2-pyrrolidyl)butyrate (44). The amino alcohol (45), obtained by reduction of 44 with lithium... 

A mixture of 57.1 g (0.1 mol) of a-ethyl-p-(3-amino-2,4,6-triiodophenyl)propionic acid, 250 ml of butyric anhydride and 1 ml of 70% perchloric acid was heated at 105°C for 5 hours. After cooling, the reaction mixture was poured onto ice, diluted to a volume of 3 liters with water, and heated on a steam bath with addition of solid sodium carbonate to keep the mixture basic. After all the excess butyric anhydride had been hydrolyzed, the mixture was made acid with dilute hydrochloric acid, the aqueous layer decanted from the resulting gummy solid, and the latter was then washed several times with water. The product was dissolved in acetic acid, decolorized with activated charcoal, and the solution while hot diluted with water to the... 

Enzymes other than CAL B have also been reported to operate under the biphasic conditions. CAL A and CAL B or a lipase from Mucor miehei were tested for the kinetic resolution of glycidol using vinyl acetate or vinyl butyrate. The enzymes were used either suspended in the free ILs or immobilized, when the reactions were carried out in [EMIM][NTf2] [71]. CALAwas inactive, butthe other two enzymes showed activity, albeit at 10-20% of that in the absence of COj whether they were free or immobilized. In general, the supported enzymes showed superior performance [71]. Chymotripsin, a specific protease for aromatic amino acids, was found to catalyze the hydrolysis or transesterification of the ethyl ester of N-acetyl-phenylalanine with propanol in scC02-[RMIM][PF5] (R = butyl or octyl) with or without added water [Eq. (15)]. 

Amino-acid analogs and uncommon L-amino acids W-acetyl-aspartate, W-acetyl-serine, oi-amino-n-butyrate, 3-aminoisobutyrate, aspartate ethyl or methyl ester, citrulline, cysteate, fumarate, glutathione, homoserine, erythro- and threo-p-hydroxyaspartate, isoasparagine, isoserine, malate, a- and p-methylaspartate, methylserine, phenol, serine amide, serine methyl ester, succinate [498, 747]... 

Ethyl N-[bis(methylthio)methylene]glycinate in dry tetrahydrofuran added drop-wise at -70° under Ng to K-t r/-butoxide in the same solvent, stirred 10 min., p-bromobenzyl bromide in tetrahydrofuran added, allowed to warm to room temp., stirred 15 min., recooled to -70°, allowed to react as above with more K-terf-butoxide and with ethyl iodide ethyl 2-[bis(methylthio)methylene]amino-2-(p-bromobenzyl)butyrate (Y 84%) dissolved in formic acid, stirred and treated at 0° with 30%-H202 and p-toluenesulfonic acid, kept 4 hrs. at 10° and 20 hrs. at 20° -> ethyl 2-ethyl-p-bromophenylalaninate (Y 90%). F. e. s. D. Hoppe, Ang. Ch. 87, 450 (1975) related synthesis and f. reactions with ethyl N-benzylidene-glycinate s. G. Stork, A.. Y. W. Leong and A. M. Touzin, J. Org. Chem. 41, 3491 (1976). 

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