Please use this identifier to cite or link to this item:
|Type:||Artigo de periódico|
|Title:||Unexpected Synthesis Of Conformationally Restricted Analogues Of γ-amino Butyric Acid (gaba): Mechanism Elucidation By Electrospray Ionization Mass Spectrometry|
|Abstract:||(Chemical Equation Presented). From previous results with lower homologues, dehydroiodination of the three alkenyl-β-enamino esters 3a-c was expected to provide six-membered N-heterocyclic products. The reactions of 3a-c with triethylamine are found to lead, however, to the unexpected stereoselective synthesis of the trisubstituted cyclopentane derivatives 4a-c, as confirmed by IR and NMR spectroscopy. Cyclopentanes 4a-c bear two chiral centers and a γ-amino ester moiety, and are therefore conformationally restricted analogues of γ-amino butyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system. Use of electrospray ionization mass (ESI-MS) and tandem mass spectrometry (ESI-MS/MS) allowed the key iminium ion intermediates 5a-c+, as well as the protonated molecules of both the reactant and final products, [3a-c + H]+ and [4a-c + H] +, to be intercepted and structurally characterized. From these findings a mechanism for this unexpected but synthetically attractive and efficient stereoselective reaction is proposed.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.