Hit-to-lead optimization of a series of carboxamides of ethyl 2-amino-4-phenylthiazole-5-carboxylates as novel adenosine A2A receptor antagonists.

Herein we describe the discovery of a series of novel adenosine A(2A) receptor antagonists. A successful hit-to-lead optimization of an HTS hit led to replacement of a metabolically labile ester moiety with a heteroaromatic group. A compound from the series, (cyclopropanecarboxylic acid [5-(5-methyl-[1,2,4]oxadiazol-3-yl)-4-phenyl-thiazol-2-yl]-amide, compound 13), was shown to be effective in reversing haloperidol-induced hypolocomotion, a model of motor dysfunction in Parkinson's Disease.