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Communication | Regular issue | Vol 65, No. 10, 2005, pp.2321-2327
Published online, 23rd August, 2005
DOI: 10.3987/COM-05-10493
First Synthesis of Piperazine-derived [1,2,4]Triazolo[1,5-a]pyrazine as an Adenosine A2A Receptor Antagonist

Hairuo Peng,* Li Sha, He Xi Chang, Jeffery T. Vessels, Serajul Haque, Patrick R. Conlon, James E. Dowling, Joy Wang, Thomas M. Engber, Gnanasambandam Kumaravel, Daniel M. Scott, and Russell C. Petter

*Departments of Medicinal Chemistry and Pharmacology, Biogen Idec, Inc., 14 Cambridge Center, Cambridge, MA 02142, U.S.A.

Abstract

Synthesis of piperazine-derived 2-furan-2-yl-[1,2,4]triazolo[1,5-a] pyrazines was achieved using methyl 3-amino-2-pyrazinecarboxylate. Introduction of the piperazine to the pyrazine template was achieved through a pteridin-4-one intermediate (7). Cyclization of the [1,2,4]triazolo[1,5-a]pyrazine ring was accomplished by amination of pyrazine (8) followed by condensation with 2-furaldehyde. Curtius rearrangement installed the amine to afford template (11). As one example of derivatizing 11, 6N-(4-(2,4,6-trifluorobenzyl)piperazin-1- yl)-2-(furan-2-yl)-[1,2,4]triazolo-[1,5-a]pyrazin-8-amine (12) showed moderate adenosine A2a receptor binding affinity and selectivity over the A1 receptor.