- On the sweetness of N-(trifluoroacetyl)aspartame.
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A panel of tasters has found that the N-trifluoroacetyl derivative of aspartame is five times less sweet than the parent compound, contrary to the tenet in the literature, but consistent with sweet receptor models which require this nitrogen to exist in protonated form.
- Frank,Aitken
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Read Online
- Direct, visible light-sensitized benzylic C[sbnd]H fluorination of peptides using dibenzosuberenone: selectivity for phenylalanine-like residues
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A visible light-sensitized benzylic sp3C[sbnd]H fluorination protocol using dibenzosuberenone (5?mol?%) and Selectfluoris optimized for the direct functionalization of phenylalanine-like residues in short chain peptides. Amino acids, dipeptides, and tripeptides undergo benzylic fluorination with remarkable regioselectivity in the presence of protected basic, acidic, and nonpolar side chains (including those with tertiary sites). Additionally, protecting group compatibility, a gram scale application, and competition experiments were explored.
- Bume, Desta Doro,Pitts, Cody Ross,Jokhai, Rayyan Trebonias,Lectka, Thomas
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supporting information
p. 6031 - 6036
(2016/09/16)
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- Preparation of N-protected α-L-aspartyl-L-phenylalanine methyl ester
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Disclosed is an improved process for the preparation of an N-protected α-L-aspartyl-L-phenylalanine methyl ester from an N-protected L-aspartic anhydride and L-phenylalanine methyl ester, the improvement which comprises employing the L-phenylalanine methyl ester in the form of a mineral acid salt thereof and conducting the reaction either (a) in an organic solvent and in the presence of a salt of an organic carboxylic acid, or (b) in an organic solvent comprising an organic carboxylic acid and in the presence of at least one member of the group consisting of an alkali metal or an alkaline earth metal inorganic base, an ammonium alkali metal or alkaline earth metal salt of an organic carboxylic acid and ammonium carbonate. The starting N-protected aspartic anhydride, e.g., N-benzyloxycarbonyl-L-aspartic anhydride, can be produced by the reaction of N-protected aspartic acid with phosgene. When the N-protecting group sibenzyloxycarbonyl and the solvent is acetic acid, the desired product can be isolated from the reaction mixture in crystalline form in high purity by adding water thereto.
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