- A green and expedient synthesis of enantiopure diketopiperazines via enzymatic resolution of unnatural amino acids
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Dipeptides comprising a d-phenylglycyl moiety coupled to the l-enantiomer of 2-amino butyric acid, norvaline, norleucine, and homocysteine were successfully synthesized from d-phenylglycine amide and the racemate of the corresponding unnatural amino acid.
- Pereira, Pedro C.,Arends, Isabel W.C.E.,Sheldon, Roger A.
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supporting information
p. 4991 - 4993
(2015/01/09)
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- Synthesis of optically active homocysteine from methionine and its use in preparing four stereoisomers of cystathionine
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In order to synthesize four stereoisomers of cystathionine (CYT), D- and L-homocysteines (D- and L-Hcy) were synthesized from methionine (Met) by a facile procedure. L-Met was reacted with dichloroacetic acid in concentrated hydrochloric acid under reflux to give (4S)-1,3-thiazane-2,4-dicarboxylic acid hydrochloride [(4S)-TDC? HCl]. L-Hcy was obtained by treatment of (4S)-TDC? HCl with hydroxylamine. D-Hcy was also synthesized from D-Met via (4R)-TDC? HCl intermediate. The obtained D- and L-Hcy were condensed with (R)- and (S)-2-amino-3-chloropropanoic acid hydrochlorides under alkaline conditions to give four stereoisomers of CYT.
- Shiraiwa, Tadashi,Nakagawa, Kazuo,Kanemoto, Norito,Kinda, Tomohiro,Yamamoto, Hiroki
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p. 1081 - 1085
(2007/10/03)
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- Facile synthesis of optically active homocysteine from methionine
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L-Methionine (L-Met) reacted with dichloroacetic acid in concentrated hydrochloric acid under refluxing to give (45)-1,3-thiazane-2,4-dicarboxylic acid hydrochloride [(4S)-TDC· HCl]. L-Homocysteine (L-Hcy) was obtained in an optically pure form by treatme
- Shiraiwa, Tadashi,Nakagawa, Kazuo,Kanemoto, Norito
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p. 468 - 469
(2007/10/03)
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- Synthesis of highly enantio-enriched α-amino acids by carboxylation of N-(α-lithioalkyl)oxazolidinones
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N-(α-Stannylalkyl)oxazolidinones can be obtained as a mixture of diastereomers in three steps from aldehydes with yields dependent on the R group of R-CHO. They can be transformed by a tin-lithium exchange to N-(α- lithioalkyl)oxazolidinones which equilibrate rapidly to one diastereomer. These compounds give rise, after carboxylation, to the diastereopure N-(α- carboxyalkyl)oxazolidinones. Transformation of the oxazolidinone moiety to a free amino group is accomplished by a Birch-type reduction. Using this method, L-methionine, L-alanine, L-leucine and L-homocysteine were obtained in good yields and ee = 92% to 95%. The short time required for the whole sequence makes this method ideal for synthesising 1-[11C]amino acids.
- Jeanjean, Fabien,Fournet, Guy,Bars, Didier Le,Gore, Jacques
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p. 1297 - 1305
(2007/10/03)
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- Preparations of Optically Active Homocysteine and Homocystine by Asymmetric Transformation of (RS)-1,3-Thiazane-4-carboxylic Acid
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DL-Homocysteine from (RS)-homocysteine thiolactone hydrochloride was subjected to reaction with formaldehyde in acetic acid to give (RS)-1,3-thiazane-4-carboxylic acid monohydrate .An asymmetric transformation of (RS)-THA*H2O was achieved via salt formation with optically active tartaric acid in the presence of salicylaldehyde in acetic acid.The (R)- and (S)-THA obtained, respectively, from the salt of (R)-THA with (2R,3R)-tartaric acid and its enantiomeric salt were treated with hydroxylamine hydrochloride to give D- and L-Hcy of 100percent optical purity, respectively, in 50percent yield from (RS)-HTL*HCl.Oxidation of D- and L-Hcy with hydrogen peroxide gave D- and L-homocystine, respectively, in 47percent yield.
- Miyazaki, Hideya,Ohta, Atsushi,Kawakatsu, Nobuyuki,Waki, Yukitaka,Gogun, Yasuhiro,et al.
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p. 536 - 540
(2007/10/02)
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- Syntheses of S-Substituted L-Homocysteine Derivatives by Cystathionine γ-Lyase of Streptomyces phaeochromogenes
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Cystationine γ-lyase from Streptomyces phaeochromogenes catalyzes not only the α,γ-elimination rection of L-cystathionine, but also the γ-replacement reaction of L-homoserine in the presence of thiol compounds.Substrates for the enzyme in the γ-replacement reaction were examined.It was found that D-cysteine, L- and D-homocysteine, and 3- and 2-mercaptopropionate served as preferable substrates in the γ-replacement reaction.D-Allocystathionine, L- and mesohomolanthionine, S-carboxyethyl-L-homocysteine and S-methylcarboxymethyl-L-homocysteine were enzymatically synthesized from L-homoserine and the corresponding thiol compounds.The thus synthesized S-substituted L-homocysteine derivatives were isolated from large scale reaction mixtures and identified physicochemically.
- Kanzaki, Hiroshi,Kobayashi, Michihiko,Nagasawa, Toru,Yamada, Hideaki
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p. 391 - 398
(2007/10/02)
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- Diastereospecific, Enzymically Catalysed Transmethylation from S-Methyl-L-methionine to L-Homocysteine, a Naturally Occuring Process
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A known catabolic pathway of S-methyl-L-methionine in higher plants: donation of a methyl group to L-homocysteine resulting in the production of two molecules of L-methionine, is subjected to stereochemical studies.The two, diastereoisomeric (2-2H, methyl-13C)-S-methyl-L-methionines are synthesized and utilised in transmethylation reactions with L-homocysteine as the acceptor and an enzyme preparation from jack beans as a catalyst.The resulting, variously labelled methionine species are converted into butyl esters of the N-trifluoroacetylated derivatives and, as such, subjected to g.l.c. combined with mass spectrometry in two ionisation modes.Experimentally determined parameters such as mass peack intensities, isotopic enrichment factors, diastereoisomeric purities, and protein-derived methionine, are utilised for calculating the stereoselectivity in the enzyme transfer of the diastereoisotopic methyl groups from S-methyl-L-methionine to L-homocysteine.Together, the independent results from the two series of diastereoisomers reveal an enzymatic preference of the pro-(R)-methyl group to the extent of 94percent or more.
- Grue-Soerensen, Gunnar,Kelstrup, Ebbe,Kjaer, Anders,Madsen, Joergen Oegaard
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p. 1091 - 1097
(2007/10/02)
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