BigPatents India

A process for the preparation of imidazo[1,2-a] pyridine derivatives of the formula I:, wherein R is hydrogen, halogen or a C1-C4 alkyl group; R1 and R2 are independently hydrogen, a straight or branched C1-C6 alkyl group which is unsubstitued or substituted by one or more halogen atoms, hydroxyl, N(C1-C4 alkyl)2, carbamoyl or C1-C4 alkoxy radicals, a C1-C6 alkyl hydroxy group, a C3-C6 cycloalkyl radical, a benzyl radical, a phenyl radical or R1 and R2 together with the nitrogen atom to which they are bonded are joined together to form a substituted or unsubstituted heterocyclic group optionally containing one or more additional heterocyclic atoms; and R3 and R4 are independently hydrogen, halogen or a C1-C4 alkyl group, or a pharmaceutically acceptable salt thereof, the process comprising (a) reacting an imidazo[1,2-a] pyridine carboxylic acid of the formula II, wherein R, R3 and R4 have the aforestated meanings with a halogenating agent in the absence of a solvent to form an acid halide intermediate and (b) reacting the acid halide intermediate with an amine of the formula HNR1R2 wherein R1 and R2 have the aforestated meanings to form the compound of formula I. Drawing: NIL Total Pages: 16 Fig. Nil