Synthesis and Characterization of Oxazolopyridine and Benzoxazole Derivatives

Synthesis of piperazinyl-substituted oxazolopyridine and benzoxazole was achieved in three steps starting from aminophenol and carbon disulfide. Condensation of aminophenols with carbon disulfide in ethanol using potassium hydroxide as catalyst gave the required benzoxazole thiol in one step. Treatment of the thiol with piperazine and substituted piperazine derivatives in toluene furnished the titled compounds in good yield. We introduced halogen substitution in the pendant arm of the piperazine derivatives for versatile functionalization. We report the synthesis and characterization of these compounds using high resolution NMR techniques.