25197-96-0Relevant academic research and scientific papers
The facile synthesis of a series of tryptophan derivatives
Blaser, Georg,Sanderson, John M.,Batsanov, Andrei S.,Howard, Judith A.K.
, p. 2795 - 2798 (2008/09/19)
This study reports a facile method for the synthesis of a variety of 5- and 6-substituted tryptophan derivatives that are difficult to prepare using alternative enzymatic approaches. Acylation of an activated amino acid, derived from serine in situ, is coupled with an enzymatic resolution step to furnish enantiopure analogues bearing a range of electron withdrawing and releasing substituents. Isolation of a dehydroalanine derivative as a by-product from some reactions provides some insights into the likely mechanism of the reaction.
Substituent Effects on the Spectral, Acid-Base, and Redox Properties of Indolyl Radicals: A Pulse Radiolysis Study
Jovanovic, Slobodan V.,Steenken, Steen
, p. 6674 - 6679 (2007/10/02)
Spectral and acid-base properties and reduction potentials of various substituted indolyl radicals were studied by pulse radiolysis in aqueous solutions at 20 deg C.Except for the 5-methoxyindolyl and 5-carboxyindolyl radicals, the spectra of the substituted indolyl radicals resemble the previously published 320- and 520-nm spectra of the neutral and 330- and 580-nm spectra of the cation indolyl and tryptophan radicals.The substitution of indolyl radical cation by electron-attracting groups (positive ?+) results in a blue shift of the 580-nm band by ca. 30 nm,, whereas the spectra of methylindolyl (?+ = -0.31) are similar to those of unsubstituted indolyl radicals.The 430- and 455-nm bands appearing in the spectra of the 5-carboxyindolyl and 5-methoxyindolyl radical cations, respectively, indicate even stronger interaction of the unpaired electron with the 5-substituent.The radical cations of various indole-3-acetic acids decarboxylate at pH values below their pKa to produce allyl radicals.The 5-bromoindolyl radical undergoes solvolysis to 5-hydroxyindolyl radical in acidic and alkaline media.The dissociation constants and reduction potentials of the substituted indolyl radicals correlate with the Brown substituent constants: pKr = 4.14 - 2.13Σ?+, correlation coefficient 0.987, and E0/0.059 = 22.29 + 3.5Σ?+, correlation coefficient 0.980.The ρ values from these correlations (-2.13 and 3.5) are similar to that of the Hammett correlation of the dissociation constants of the protonated indole nitrogen in various substituted indoles, ρ = -2.49, but smaller than the ρ value of the dependence on the substituent of the reduction potentials of phenoxyl radicals, ρ = 5.4.
Syntheses of Substituted L- and D-Tryptophans
Irie, Kunihiko,Ishida, Akihiko,Nakamura, Tohru,Oh-ishi, Tokuro
, p. 2126 - 2139 (2007/10/02)
Several 5-substituted nb-methoxycarbonyl-L- and -D-tryptophan derivatives were synthesized from proline by a new route involving electrochemical oxidation, as well as by the known procedures.Removal of the Nb-methoxycarbonyl group was accomplished by treatment with Me3SiI in refluxing chloroform, then alkaline hydrolysis of the methyl esters afforded 5-substituted L- and D-tryptophans with high optical purities.Keywords - L-tryptophan 5-substituted; D-tryptophan 5-substituted; anodic oxidation; N-methoxycarbonyl group deprotection; Fischer indole synthesis; iodotrimethylsilane
