- SYSTEMES DE STRECKER ET APPARENTES - XI FORMATION ET STABILITE DE L'α-CARBOXYAMINONITRILE. INTERMEDIAIRE ESSENTIEL DANS LA SYNTHESE DES HYDANTOINES SELON BUCHERER-BERGS
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The determination of the structure of the intermediate in the Bucherer-Bergs reaction (the transformation in aqueous solution of an aldehyde into the corresponding amino-acid via the hydantoin) showed that this reaction involved the formation of α-aminonitrile carbamate.The slow formation of the carbonic anhydride from the carbonate buffer limited the formation of that main intermediate which was in equilibrium with the α-aminonitrile.The variation of the stability of the carbamate vs pH is mainly determined by the concentration of CO2 dissolved in the mixture, but also by the equilibrated formation of products formed by the degradation of α-aminonitrile, i.e. the aminodinitrile and the cyanohydrin.
- Rousset, A.,Lasperas, M.,Taillades, J.,Commeyras, A.
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- Synthesis of aldehydic ribonucleotide and amino acid precursors by photoredox chemistry
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Light work: UV irradiation of a system formed by adding copper(I) cyanide to an aqueous solution of glycolonitrile, sodium phosphate, and hydrogen sulfide efficiently generates aldehyde precursors to the building blocks of RNA and proteins. Copyright
- Ritson, Dougal J.,Sutherland, John D.
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supporting information
p. 5845 - 5847
(2013/07/11)
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- Regioselectivity of the photochemical addition of ammonia, phosphine, and silane to olefinic and acetylenic nitriles
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An investigation of the regioselectivity and mechanisms of the photochemical addition of NH3, PH3, and SiH4 to olefinic and acetylenic nitriles is described. The photolysis of NH3 in the presence of acrylonitrile led to the α-addition product 2-aminopropanenitrile (2), propanenitrile, and 2,3-dimethylbutanedinitrile (3). When NH3 was photolyzed in the presence of substituted derivatives (crotononitrile, methacrylonitrile, or 1-cyclohexenecarbonitrile), the α-addition products were still obtained. However, under similar reaction conditions, only the β-addition products, 7 and 8, were obtained from acrylonitrile and PH3, or acrylonitrile and SiH4, respectively. On the other hand, the photolysis of 2-butynenitrile and NH3 gave the β-addition products, (Z)- and (E)-3-aminocrotononitrile (10). The photolysis of these acetylenic nitriles with PH3 or SiH4 also gave the β-adducts (12) and (13). The α-addition of NH3 proceeds by the stepwise addition of H· and ·NH2, respectively, to the α,β-unsaturated nitriles. The β-addition products are formed by a radical chain mechanism initiated by photochemically generated radicals. The radical chain pathway provides an explanation for a number of previously described photochemical additions to olefins and acetylenes. Photochemical processes similar to the addition of ammonia and phosphine to unsaturated organic compounds may have played a role in the evolution of the atmosphere of the primitive Earth, and may even be currently occurring in the atmospheres of other planets.
- Guillemin, Jean-Claude,Breneman, Curt M.,Joseph, Jeffrey C.,Ferris, James P.
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p. 1074 - 1082
(2007/10/03)
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- Chemie der α-Aminonitrile. 1. Mitteilung. Einleitung und Wege zu Uroporphyrinogen-octanitrilen
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Chemistry of α-Aminonitriles I: Introduction and Pathways to Uroporphyrinogen-octanitriles.An introduction to experimental studies on the chemistry of α-aminonitriles potentially relevant to the problems of prebiotic chemistry is presented.The framework of conditions wherein the investigations is chosen to be carried out implies both molecular oxygen and - whenever feasible - water to be excluded from reaction conditions.This study focusses on 2-amino-2-propenenitrile (3) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5).Schemes 13, 16, 23 as well as 25, and 26 summarize reaction sequences by which 3 is tranformed within the definied framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroporphyrinogen-octanitriles 57-60.HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one present in all biological porphinoids.Preparative procedures for the synthesis of 3 (Scheme 9), the β,β-disubstututed pyrrol-nitriles 30, 53, and 54 (Scheme 19) as well as the porphyrinogen-octakis(propionitrile) and -octakis(acetonitrile) 65 and 66, respectively (Scheme 24) are given.
- Ksander, Gary,Bold, Guido,Lattmann, Rene,Lehmann, Christian,Frueh, Thomas,et al.
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p. 1115 - 1172
(2007/10/02)
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