ABSTRACT
(R)-α-Aminoadipic acid is a readily available enantiomerically pure starting material for the synthesis of (R)-pipecolic acid and its derivatives. Sonogashira or Suzuki cross-coupling reactions of an N-formyl pipecolate-derived vinyl bromide furnish 6-alkynyl or aryl derivatives. Reduction with sodium cyanoborohydride and subsequent N-deformylation provide 6-alkynyl substituted (R)-pipecolic acid derivatives, valuable building blocks for amino acid and peptide chemistry.
Subject(s)
2-Aminoadipic Acid/chemistry , 2-Aminoadipic Acid/chemical synthesis , Amino Acids/chemistry , Cross-Linking Reagents/chemistry , Peptides/chemistry , Pipecolic Acids/chemistry , Pipecolic Acids/chemical synthesis , Molecular Structure , StereoisomerismABSTRACT
Homologation and substitution on the carbon backbone of (S)-glutamic acid [(S)-Glu, 1], as well as absolute stereochemistry, are structural parameters of key importance for the pharmacological profile of (S)-Glu receptor ligands. We describe a series of methyl-substituted 2-aminoadipic acid (AA) analogs, and the synthesis, stereochemistry, and enantiopharmacology of 3-methyl-AA (4a-d), 4-methyl-AA (5a-d), 5-methyl-AA (6a-d), and (E)-Delta(4)-5-methyl-AA (7a and 7b) are reported. The compounds were resolved using chiral HPLC and the configurational assignments of the enantiomers were based on X-ray crystallographic analyses, chemical correlation, and CD spectral analyses. The effects of the individual stereoisomers at ionotropic and metabotropic (S)-Glu receptors (iGluRs and mGluRs) were characterized. Compounds with S-configuration at the alpha-carbon generally showed mGluR2 agonist activity of similar or slightly lower potencies than (S)-AA [e.g., EC(50) = 76 microM for (2S,4S)-4-methyl-AA (5a) as compared to EC(50) = 35 microM for (S)-AA]. The position of the methyl substituent had a profound effect on the observed pharmacology, whereas the absolute stereochemistry at the methylated carbon atom had a very limited effect on pharmacology. Structure-activity relationships at iGluRs in the rat cortical wedge preparation showed a complex pattern, some compounds being NMDA receptor agonists [e.g., EC(50) =110 microM for (2S,5RS)-5-methyl-AA (6a,b)] and some compounds showing NMDA receptor antagonist effects [e.g., IC(50) = 300 microM for (2R,4S)-4-methyl-AA (5d)]. The two unsaturated analogs (S)- (7a) and (R)-(E)-Delta(4)-5-methyl-AA (7b) turned out to be a weak AMPA receptor agonist and a weak mixed NMDA/AMPA receptor antagonist, respectively.
Subject(s)
2-Aminoadipic Acid/analogs & derivatives , Receptors, Glutamate/metabolism , 2-Aminoadipic Acid/chemical synthesis , 2-Aminoadipic Acid/chemistry , 2-Aminoadipic Acid/metabolism , Animals , CHO Cells , Circular Dichroism , Cricetinae , Crystallography, X-Ray , In Vitro Techniques , Ligands , Methylation , Models, Molecular , Rats , Recombinant Proteins/metabolism , StereoisomerismSubject(s)
2-Aminoadipic Acid/analogs & derivatives , 2-Aminoadipic Acid/chemical synthesis , Acetals/chemical synthesis , Anti-Bacterial Agents/chemical synthesis , Picolinic Acids/chemical synthesis , 2-Aminoadipic Acid/chemistry , 2-Aminoadipic Acid/metabolism , Acetals/chemistry , Anti-Bacterial Agents/biosynthesis , Chromatography, High Pressure Liquid , Picolinic Acids/chemistry , beta-LactamsABSTRACT
Sixteen gamma-linked dipeptide and four L-Glu-gamma-amide analogues of 2-desamino-2-methyl-N10-propargyl-5,8-dideazafolic acid (ICI 198583) have been synthesized and evaluated as inhibitors of thymidylate synthase (TS). Z-blocked L-Glu-gamma-L-linked dipeptides and L-Glu-gamma-amides were prepared by condensing alpha-tert-butyl-N-(benzyloxycarbonyl)-L-glutamic acid with the appropriate tert-butyl-protected L-amino acid or amine. The Z group was removed by catalytic hydrogenolysis, and the resulting dipeptides or L-Glu-gamma-amides were condensed with the appropriate pteroic acid analogue trifluoroacetate salt using diethyl cyanophosphoridate as coupling reagent. Deprotection with trifluoroacetic acid in the final step gave the desired quinazoline gamma-linked dipeptides and L-Glu-gamma-amides as their trifluoroacetate salts. Nearly all the dipeptide analogues were potent inhibitors of TS, the best being ICI 198583-gamma-L-2-aminoadipate (IC50 = 2 nM). Several of these dipeptides were found to be susceptible to enzymatic hydrolysis in mice. The quinazoline monocarboxylate L-Glu-gamma-amides, lacking an alpha'-carboxyl group, are less active against TS and L1210 cell growth but are also not susceptible to enzymatic hydrolysis in mice.
Subject(s)
2-Aminoadipic Acid/analogs & derivatives , Dipeptides/chemistry , Folic Acid/analogs & derivatives , Thymidylate Synthase/antagonists & inhibitors , 2-Aminoadipic Acid/chemical synthesis , 2-Aminoadipic Acid/pharmacology , Animals , Binding Sites , Cell Division/drug effects , Dipeptides/pharmacology , Drug Stability , Folic Acid/chemical synthesis , Folic Acid/chemistry , Folic Acid/pharmacology , Glutamic Acid/chemistry , Hydrolases/metabolism , Hydrolysis , Leukemia L1210/pathology , Mice , Structure-Activity RelationshipABSTRACT
The four D-2-amino-4,5-methano-adipates 26, 27, 32, 33 were synthesized and their biological activity at the N-methyl-D-aspartate (NMDA) receptor was assessed. The synthesis involved as a key step a rhodium acetate dimer catalyzed addition of ethyl diazoacetate to the protected D-allylglycine (17). In vitro receptor binding using L-[3H]glutamate as the radioligand provided affinity data, while modulation of [3H]TCP binding was used as a functional assay. The analogues were also evaluated in [3H]kainate and [3H]AMPA binding to assess selectivity over non-NMDA glutamate receptors. Three of the four diastereoisomer, D-CAA B (27), C (32) and D (33) were shown to have agonist properties at the NMDA-site, while the fourth, (2R,4R,5R) D-CAA A (26) was characterized as an NMDA-site atypic antagonist.
