ABSTRACT
A new class of nipecotic acid and guvacine derivatives has been synthesized and characterized for their inhibitory potency at mGAT1-4 and binding affinity for mGAT1. Compounds of the described class are defined by a four-carbon-atom allenyl spacer connecting the nitrogen atom of the nipecotic acid or guvacine head with an aromatic residue. Among the compounds investigated, the mixture of nipecotic acid derivatives rac-{(Ra )-1-[4-([1,1':2',1''-terphenyl]-2-yl)buta-2,3-dien-1-yl](3R)-piperidine-3-carboxylic acid} and rac-{(Sa )-1-[4-([1,1':2',1''-terphenyl]-2-yl)buta-2,3-dien-1-yl](3R)-piperidine-3-carboxylic acid} (21 p), possessing an o-terphenyl residue, was identified as highly selective and the most potent mGAT1 inhibitor in this study. For the (R)-nipecotic acid derived form of 21 p, the inhibitory potency in [3 H]GABA uptake assays was determined as pIC50 =6.78±0.08, and the binding affinity in MS Binding Assays as pKi =7.10±0.12. The synthesis of the designed compounds was carried out by a two-step procedure, generating the allene moiety via allenylation of terminal alkynes which allows broad variation of the terminal phenyl and biphenyl subunit.
Subject(s)
Alkenes/chemical synthesis , Alkenes/pharmacology , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , N-Acetylglucosaminyltransferases/antagonists & inhibitors , Nicotinic Acids/pharmacology , Nipecotic Acids/pharmacology , Alkenes/chemistry , Animals , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemistry , HEK293 Cells , Humans , Mice , Molecular Structure , N-Acetylglucosaminyltransferases/metabolism , Nicotinic Acids/chemical synthesis , Nicotinic Acids/chemistry , Nipecotic Acids/chemical synthesis , Nipecotic Acids/chemistry , Structure-Activity RelationshipABSTRACT
The relative reactivities of several secondary amines serving as hydride donors in propargylic amines undergoing a [1,5]-hydride transfer reaction to yield the respective terminal and 1,3-disubstituted allenes were studied. For this study, a two-step procedure was employed. At first, the synthesis of propargylic amines via the CuI-catalyzed aldehyde-alkyne-amine reactions (A3 coupling) was accomplished. The obtained propargylic amines were subsequently transformed to the desired allenes under CdI2 or ZnI2 catalysis. As a result, among the various secondary amines employed, differing in steric bulk, electronic nature, and conformational properties, allyl(tert-butyl)amine was found to be the best hydride donor for the synthesis of terminal allenes. For the synthesis of 1,3-disubstituted allenes, the propyne derivatives containing either a allyl(tert-butyl)amine or a 1,2,3,6-tetrahydropyridine unit in propargylic position performed best. Finally, with the developed procedure, nipecotic acid derivatives containing an N-allenyl substituent were synthesized with good yields using either ZnI2 as catalyst for the preparation of 1-substituted or CdI2 for the synthesis of 1,3-disubstitued allenes.
