- Synthesis of α-amino and α-hydroxy acids under volcanic conditions: implications for the origin of life
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Facile synthesis of α-hydroxy and α-amino acids is observed at temperatures from 145 to 280 °C with catalytic Ni2+, with cyano ligands as source for C and N, and with CO as a reductant and as a source for C. Implications for the problem of the origin of life are discussed.
- Huber, Claudia,Eisenreich, Wolfgang,W?chtersh?user, Günter
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scheme or table
p. 1069 - 1071
(2010/04/05)
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- New heterocycles from the reaction between some natural α-amino acid hydrazides and formaldehyde
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The ring forming condensation between some natural α-amino acid phenylhydrazides (1) and aqueous formaldehyde (2) has opened a novel synthetic route to hexahydro-1,2,4-triazin-6-one derivatives (3). Polycyclic systems were obtained from the same reaction carried out with L-aspartic acid 1,4-bis(2-phenylhydrazide) (1d), L-histidine phenylhydrazide (1e) and L- tryptophan phenylhydrazide (1f) which gave perhydro-4,6-dioxo-2,8- diphenyl[1,2,4]triazino[4,5-d][1,2,4]triazepine (5) perhydro-1-oxo-3- phenylimidazo[5,4-d][1,2,4]triazino[4,5-a]pyridine (7) and 1,2,3-H-3-(2- phenylcarbazoyl)-β-carboline (8), respectively. Substrates 1 were conveniently obtained by direct reaction of phenylhydrazine with L-α-amino acid esters retaining the original chirality.
- Verardo, Giancarlo,Toniutti, Nicoletta,Gorassini, Andrea,Giumanini, Angelo G.
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p. 2943 - 2948
(2007/10/03)
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- α-Aminonitrile hydration in the presence of hydrogen peroxide in aqueous basic medium
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α-Aminonitriles are hydrated into α-aminoamides in the presence of hydrogen peroxide in sodic or ammoniacal basic medium. While the hydration mechanism is close to the mechanism described previously in the case of aromatic nitrites, we showed that, in weakly basic conditions, the amine function of α-aminonitrile is competitively oxidized via a peroxyimidic acid by an intramolecular process. In the case of 2-aminopropanenitrile, this reaction leads to pyruvamide oxime. Furthermore, the study of structurereactivity relationships in the hydration of aliphatic and aromatic monofunctional nitriles and α-aminonitriles showed that the reactivity of the substrates towards hydroperoxide onion, which mostly depends on inductive effects of the substituents, is sufficiently enhanced to allow hydration of tertiary α-aminonitriles with low steric hindrance and regioselective hydration of dissymmetric α-aminodinitriles. Eisevier,.
- Taillades, Jacques
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- Process for recimization of an optically active alpha-amino acid amides and process for producing optically active alpha-amino acids
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A process for optically isomerizing an optically active alpha-amino acid amide comprising heating a D-alpha-amino acid amide or an L-alpha-amino acid amide in the presence of a strongly basic compound; and a process for producing an L-alpha-amino acid, which comprises (1) subjecting a D,L-alpha-amino acid amide or a mixture of a major amount of a D-alpha-amino acid amide and a minor amount of an L-alpha-amino acid amide to the action of a microorganism having the ability to hydrolyze the L-alpha-amino acid to obtain a hydrolyzate containing the L-alpha-amino acid and D-alpha-amino acid, (2) separating the L-alpha-amino acid from the hydrolyzate and recovering the remaining D-alpha-amino acid amide. (3) heating all or part of the recovered D-alpha-amino acid amide in the presence of a strongly basic substance to obtain a D,L-alpha-amino acid amide or a mixture of a major amount of the D-alpha-amino acid amide and a minor amount of the L-alpha-amino acid amide, and (4) recycling the D,L-alpha-amino acid amide or the mixture to step (1) as part or all of the starting material.
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- Mecanisme de la reaction de Bucherer-Bergs Comparaison avec l'hydratation basique des α-aminonitriles
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The Bucherer-Bergs reaction provides an important tool for the synthesis of α-aminoacids and is the basis of an industrial process for producing methionine.The key compound is the α-aminonitrile 1 which leads to partial decomposition in carbonate buffer as well as in weakly basic aqueous media and to the equilibrated formation of the basic intermediate α-carboxy-aminonitrile 2a.The parameters which control the stability of 2a are summarised.These equlibria are established through an initial fast step which is then followed by the formation of the hydantoin 5a.At a constant pH this formation is first order in α-carboxyaminonitrile 2a via a 5-imino-2-oxazolidinone 3a and an α-isocyanatamide 4a.A comparison of the reactivity of 1 with that of the N-alkylated compouds 7 shows that the rate determining step of the hydantoin formation is the cyclisation of 2a at pH9.But at higher pH, the reaction is controlled by the fast partitioning of the cyclic intermediate 3a between the α-carboxyaminonitrile 2a and the isocyanatamide 4a.This study permits the direct comparison between two mechanism for the synthesis of the racemic α-aminoacids: the Bucherer-Bergs way and the catalytic hydratation of α-aminonitriles.It is clear that carbonic anhydre can be considered as a special carbonyl compound with respect to its reactivity towards α-aminonitriles.
- Taillades, Jacques,Rousset, Alain,Lasperas, Monique,Commeyras, Auguste
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p. 650 - 658
(2007/10/02)
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