Abstract A series of substituted 2-aryl imidazo [1, 2-a] pyridines has been prepared in which a variety of substituents are introduced on the 4′-position of the phenyl ring and on the 3, 5, 6 or 7 position of the heterocyclic ring. Most examples have acetamido, bromo, cyano, or formyl substituents at the 4′-position. Analogous imidazo-[2, 1-b] fhiazoles and imidazo [1, 2-a] pyrimidines have also been prepared. Another series of compounds consisting of 4′ ...