16709-25-4Relevant articles and documents
Chiral ligand-exchange resolution of underivatized amino acids on a dynamically modified stationary phase for RP-HPTLC
Remelli, Maurizio,Faccini, Stefania,Conato, Chiara
, p. 313 - 318 (2014/06/09)
The synthesis of Spi(τ-dec), derived from the selective alkylation of L-spinacine (4,5,6,7-tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid) at the τ-nitrogen of its heteroaromatic ring, with a linear hydrocarbon chain of 10 carbon atoms, is described here for the first time. Spi(τ-dec) was successfully employed in the past to prepare home-made chiral columns for chiral ligand-exchange high-performance liquid chromatography. In the present article a new method is described, using Spi(τ-dec) as a chiral selector in high-performance thin-layer chromatography (HPTLC): commercial hydrophobic plates were first coated with Spi(τ-dec) and then treated with copper sulfate. The performance of this new chiral stationary phase was tested against racemic mixtures of aromatic amino acids, after appropriate optimization of both the conditions of preparation of the plates and the mobile phase composition. The enantioselectivity values obtained for the studied compounds were higher than those reported in the literature for similar systems. The method employed here for the preparation of chiral HPTLC plates proved practical, efficient, and inexpensive. Chirality 26:313-318, 2014. 2014 Wiley Periodicals, Inc.
Asymmetric synthesis of α-Methyl α-Amino Acids through diastereoselective alkylation under mild reaction conditions of an iminic alanine template with a 1,2,3,6-Tetrahydro-2-Pyrazinone structure
Najera, Carmen,Abellan, Tomas,Sansano, Jose M.
, p. 2809 - 2820 (2007/10/03)
(6R)-6-Isopropyl-3-methyl-5-phenyl-1,2,3,6-tetrahydro-2-pyrazinone, obtained from (R)-valine and (S)-alanine, is highly diastereoselectively alkylated at room temperature by: a) activated alkyl halides under solid-liquid PTC conditions, b) non-activated alkyl halides with organic bases, c) electrophilic olefins employing both solid-liquid PTC conditions and organic bases, and d) allylic carbonates by means of palladium catalysis under neutral conditions. Enantiomerically pure (S)-α-methyl α-amino acids 8 are obtained by hydrolysis of the alkylated pyrazinones.
Pharmacokinetics of α-methyl-L-tryptophan in rhesus monkeys and calculation of the lumped constant for estimating the rate of serotonin synthesis
Shoaf, Susan E.,Schmall, Bernard
, p. 219 - 224 (2007/10/03)
We have determined several kinetic and pharmacokinetic parameters of L- tryptophan (Trp) and α-methyl-L-tryptophan (αMTrp) in the rhesus monkey from which the lumped constant for the αMTrp method of estimating serotonin synthesis rates is calculated. αMTrp was isolated from DL-αMTrp using a chiral separation column with high performance liquid chromatography. αMTrp (50 μg/kg) was administered i.v. to four adult male rhesus monkeys and arterial blood samples were collected for a 4-hr period. Plasma concentrations, as determined by high performance liquid chromatography with electrochemical detection, were best fitted by a tri-exponential equation. Plasma protein binding of Trp and αMTrp was determined by measuring concentrations in ultrafiltrates obtained at 30°C. After a 2-hr adjusted rate infusion of αMTrp designed to establish steady-state plasma concentrations, three adult male rhesus monkeys were killed by exsanguination with perfused ice-cold saline. Brain/arterial plasma concentration ratios of Trp and αMTrp and the Michaelis-Menten parameters for tryptophan hydroxylase, EC 1.14.16.4, with Trp and αMTrp as initiating substrates, were determined for seven brain regions. The lumped constants determined for the different brain regions were not significantly different from each other and indicate, that for modeling purposes, the brain may be treated as a homogeneous area and the lumped constant given a single value, 0.18 ± 0.05.
