1346773-61-2Relevant articles and documents
Synthesis of ortho-carboranyl derivatives of (S)-asparagine and (S)-glutamine
Gruzdev,Levit,Olshevskaya,Krasnov
, p. 769 - 776 (2017)
(S)-Asparagine and (S)-glutamine ortho-carboranyl derivatives with free amino and carboxy groups in the α-position were synthesized. By an example of Nγ-(1,2-dicarba-closo-dodecarboran-3-yl)-(S)-glutamine it was demonstrated that the developed synthetic approach carboranyl derivatives of amino acids allowed the preparation of optically pure isomers.
A practical method for selective cleavage of a tert-butoxycarbamoyl N-protective group from N,N-diprotected α-amino acid derivatives using montmorillonite K-10
Hernandez, J. Nicolas,Crisostomo, Fernando R. Pinacho,Martin, Tomas,Martin, Victor S.
, p. 5050 - 5058 (2008/03/18)
A new, practical, and mild procedure for the selective cleavage of a tert-butoxycarbonyl group (Boc) in N-Boc-N-acyl-diprotected amines is described. When applied to α-amino acids, complete integrity of the stereochemistry was observed. The use of N,N-di-Boc-α-amino-δ- and γ-hydroxy esters provided both δ- and γ-lactones in very good yields. The method is based on the use of Montmorillonite K-10 either in CH 2Cl2 at room temperature or in toluene at 65°C and is compatible with the presence of a large range of functional and other protecting groups in the substrates. In most cases virtually pure samples are obtained after filtration and removal of solvents. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
An Approach to Trapping γ-Glutamyl Radical Intermediates Proposed for Vitamin K Dependent Carboxylase: α,β-Methyleneglutamic Acid
Slama, James T.,Satsangi, Rajiv K.,Simmons, Anne,Lynch, Vincent,Bolger, Randall E.,Suttie, John
, p. 824 - 832 (2007/10/02)
The vitamin K dependent carboxylase activates the glutamyl γ-CH of substrate peptides for carboxylation by producing a γ-glutamyl free radical, a γ-glutamyl carbanion, or through a concerted carboxylation.We propose to intercept the putative γ-glutamyl free radical by the intramolecular rearrangement of a substrate containing the α,β-cyclopropane analogue of glutamic acid.The rearrangement of cyclopropylcarbinyl radicals into 2-butenyl radicals is rapid, exothermic, and considered diagnostis of free-radical formation.1-Amino-2-(carboxymethyl)cyclopropane-1-carboxylate, the β-cyclopropane analogue of glutamic acid, was synthesized starting from diethyl α-ketoglutarate.The α-keto ester was first treated with benzonitrile in sulfuric acid, to yield diethyl α,α-dibenzamidoglutarate.The α,α-dibenzamido acid was cleaved to produce the α,β-dehydroamino acid and benzamide on treatment with p-toluenesulfonic acid in hot benzene.Diazomethane addition to the dehydroamino acid resulted in cycloaddition of diazomethane and production of the pyrazoline, which upon irradiation lost N2 to give the protected cyclopropane-containing amino acid analogue.Acid hydrolysis of the N-benzoyl-α,β-methyleneglutamate diethyl ester resulted in the production of the unprotected amino acid, α,β-methyleneglutamic acid, in high yield.A single dehydroamino acid and a single methyleneglutamic acid isomer were produced in this synthesis; both are identified as the Z isomer, the former by NMR using the nuclear Overhauser effect and the latter through X-ray crystallographic analysis of N-benzoyl-α,β-methyleneglutamate diethyl ester.Saponification of a N-protectedmethyleneglutamic acid dialkyl ester using limiting alkali was shown to selectively yield the α-alkyl ester γ-acid.The reaction was used to produce α,β-cyclopropane-containing analogues of the carboxylase substrates N-t-Boc-L-glutamic acid α-benzyl ester and N-benzoyl-L-glutamic acid α-ethyl ester.The cyclpropane-containing analogues were tested and found to be neither substrates for nor inhibitors of the rat liver microsomal vitamin K dependent carboxylase.The inability of the enzyme to recognize these substrate analogues is attributed to the α-alkyl substitution, which apparently abolishes substrate binding.
