NEW PROCESS FOR THE SYNTHESIS OF IMIDAZO[4,5-B]PYRIDINE DERIVATIVES AS POTENT ORALLY-ACTIVE THROMBOXANE-A2 RECEPTOR ANTAGONISTS

A new synthetic route to prepare the roimidazo[4,5-b]pyridin-2-yl]-3,3 -dimethylbutanoic acid (UP 116-77) is described. UP 116-77 is a potent orally active TXA2/PGH2 receptor antagonist currently under pharmacol ogical investigation. Its development needed a suitable synthesis for industrial processing. The cyclization of ino-5-chloro-2-(4-chlorophen yl)methylaminopyridine 4 with 3,3-dimethylglutaric anhydride in reflux ing acetic acid affords a new efficient and simple way to UP 116-77 an d subsequently to various 2-substituted imidazo[4,5-b]pyridine derivat ives.