6182-84-9Relevant academic research and scientific papers
Trichosporon beigelli esterase (TBE): A versatile esterase for the resolution of economically important racemates
Koul, Surrinder,Koul, Jawahir Lal,Singh, Budh,Kapoor, Munish,Parshad, Rajinder,Manhas, Kuldeep S.,Taneja, Subhash C.,Qazi, Ghulam N.
, p. 2575 - 2591 (2007/10/03)
A hydrolase producing strain Trichosporon beigelli esterase (TBE) isolated from local cottage cheese in its native form has displayed versatility and high efficacy in the kinetic resolution of a wide range of economically important substrates, which include racemic secondary alcohols, such as 1-(6-methoxy-2-naphthyl)ethanol (E ～ 316), 1-(3,4-methylenedioxyphenyl) ethanol and pentanol (E ～ 180 and 156 resp.), and alkyl esters of carboxylic acids such as ibuprofen (E ～ 340), 2-(benzylthio)propanoic acid (E ～ 1000). In other substrates such as in the primary alcohol 2-(6-methoxy-2- naphthyl)propan-1-ol and carboxylic acids such as 2-(5-bromo-6-methoxy-2- naphthyl)propanoic acid, 2-(2-naphthyloxy)propanoic acid, and substituted 2-thiopropanoic acids, it displayed moderate to low selectivity. Commercial lipases such as CCL, PPL, and PSL were also used in the resolution of the substrates for comparative studies.
Dynamic enzymatic resolution of thioesters
Um, Pil-Je,Drueckhammer, Dale G.
, p. 5605 - 5610 (2007/10/03)
A detailed investigation of several issues related to the enzymatic resolution of thioesters under conditions of continuous racemization of substrate was conducted. The kinetic acidity of the α-protons of a series of α-substituted propionate thioesters was studied. It was found that the rate of α-proton exchange could be enhanced as much as 20-fold by variation of the thiol moiety, increasing the range of compounds to which enzymatic dynamic resolution may be applied. The relative rates of hydrolysis of ethyl butyrate and ethyl thiobutyrate by several enzymes commonly used in enzymatic resolution were determined. All of the enzymes studied exhibited similar rates of thioester and oxoester hydrolysis except for the esterase from pig liver, which showed very low activity in thioester hydrolysis. Dynamic resolution of the propargyl and trifluoroethyl thioesters of α- phenylpropionate was conducted using subtilisin Carlsberg as a catalyst. These examples demonstrated that enzymatic dynamic resolution can be applied even when the rate of α-proton exchange and the enantioselectivity of the enzyme are fairly low. A dynamic enzymatic transesterification procedure was demonstrated in the resolution of the trifluoroethyl thioester of α-(2,4- dichlorophenoxy)propionate, and product was obtained in 93% ee. This work helps expand and define the scope of enzymatic dynamic resolution of thioesters.
Mass Spectrometry of 2-Alkylthio-2-methylpropanoic Acids and Their Esters and Amides. Structural and Steric Effects on the McLafferty Rearrangement
Mori, Yuji,Fujiwara, Shigeru,Miyachi, Toshiko,Kitanishi, Hiroyuki,Oya, Masayuki,et al.
, p. 1505 - 1517 (2007/10/02)
The electron ionization mass spectra (MS) of S-methylated derivatives of N-(2-mercapto-2-methylpropanoyl)-L-cysteine and 2-alkylthio-2-methylpropanoic acids, as well as their esters and amides, were examined.Use of the deuterium labeling technique and accurate mass measurement supported the proposed fragmentation pathways.Extensive loss of CH2S from a molecular ion by the McLafferty rearrangementof a primary hydrogen is important in the MS of S-methyl compounds of amide derivatives.It was demonstrated that the intensity of the rearrangement ion decreases in the order of amide, ester, and acid, and in the case if amides the reaarangement is suppressed by the nonbonded interaction between methyl groups on the α carbon and the amide nitrogen.Keywords-N-(2-mercapto-2-methylpropanoyl)-L-cysteine; 2-alkylthio-2-methylpropanoic acid and methyl ester; 2-alkylthio-2-methylpropanamide; electron impact mass spectrometry; McLafferty rearrangement; steric interaction
