A novel series of Se-heterocyclic compounds, which containing azo-dye and organoselenium moieties, have been synthesized by the reaction of 4,6-diamino-2-(methylselanyl)pyridine-3-carbonitrile (1) with aromatic diazonium chloride salts. Furthermore, oxobutanamide 3 was obtained via N-acetylation of methylselanyl pyridine 1 by ethyl acetoacetate. Product 3 was used as a starting material to synthesize aryl hydrazones 4a and 4b. However, an unprecedented series of thiapyridine derivatives 7a and 7b was produced through a one-pot multicomponent reaction of methylselanyl pyridine 1 with chloroacetyl chloride and thiophenol derivatives.