- Anodic oxidation of α-aminoacids
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Anodic oxidation of N-acetyl-β-phenylalanine (1) was performed at constant current in different conditions in CH3OH/CH3ONa. The products were identified using 1H-NMR, 13C-NMR and GC-MS. The main product (78%) that was isolated is a methoxyderivative having an unrearranged skeleton. A small amount of isomerized product and an important proportion (20%) of products having higher molecular masses are formed. A scheme explaining their formation is proposed. The results underline the stabilization of the anodically generated carbocation by the nitrogen atom.
- Ungureanu, Eleonora Mihaela,Stanciu, Gabriela,Rosca, Sorin Ioan
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p. 869 - 875
(2007/10/03)
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- ELECTROCHEMICAL AND PHOTOCHEMICAL PREPARATION OF N-ACYLATED α-METHOXY-PHENETHYLAMINE. FAILURE TO CONVERSION INTO PHENYLALANINE.
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Anodic oxidation of N-methoxycarbonyl phenethylamine in MeOH at pH 9 proceeds quantitatively although only 45percent conversion can be reached in a simple undivided electrocell as the result of the formation of an obstructing precipitate.Treatment of several N-acyl-α-methoxy derivatives with cyanide results in elimination instead of substitution.The preparation of Phe from the above-mentioned synthons therefore was unsuccessfull.
- Callens, R.,Anteunis, M. J. O.,Witte, M. De
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p. 619 - 622
(2007/10/02)
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- THE PHOTOELIMINATION OF N-NITROSO-N-ACETYL-α-AMINO-ACIDS; A NEW SYNTHESIS OF 1,2,4-OXADIAZOLES
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The excitation of N-nitroso-N-acetyl-α-aminoacids, nitrosopeptide model compounds, under neutral and weakly basic conditions, caused the homolysis of the N-N bond followed by decarboxylation to give hyponitrous acid (HNO) and N-acetylimines which were susceptible to nucleophilic addition.While weak bases caused the carboxylate group to assist intramolecular rearrangement to a small extent, they functioned primarily to provide nucleophilic NO-, which initiated nucleophilic attack leading to the C-nitroso derivatives.These C-nitroso derivatives spontaneously cyclized to 1,2,4-oxadiazoles much more rapidly than tautomerism to the corresponding oximes; the latter oximes failed to cyclize under the basic conditions.
- Chow, Yuan L.,Polo, Joel S.
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p. 727 - 734
(2007/10/02)
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- Synthesis of N-(α-Methoxyalkyl) Amides from Imidates
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Two general routes from imidates to N-(α-methoxyalkyl) amides (e.g.,R'CONHCH(OCH3)R, 1) are reported.The first involves acylation of the imidate on nitrogen with an acyl chloride, followed by reduction with sodium borohydride.In the second, an aldehyde is converted, via its methyl acetal, to an α-chloro methyl ether, which is used to alkylate the imdate.Further treatment with pyridinium chloride in dry Me2SO yields 1.Thirteen examples are reported.
- Lokensgard, Jerrold P.,Fischer, John W.,Bartz, William J.
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p. 5609 - 5611
(2007/10/02)
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