Facile microwave-assisted synthesis of 2-aryloxazolo[4,5-b] pyridines using SBA-Pr-NH2

In this work, amino-functionalized SBA-15 (SBA-Pr-NH2) has been used as a basic nano-catalyst in the one-pot synthesis of 2-aryloxazolo[4,5-b]pyridines by the condensation reaction of 2-amino-3-hydroxypyridine and benzoyl chlorides under microwave irradiation in solvent free conditions. Among the advantages of this work are short reaction times, high yields and simple work-up. SBAPr- NH2 as an efficient heterogeneous nanoporous solid basic catalyst which was prepared by silica functionalization with 3-aminopropyltriethoxysilane, can be easily removed from the reaction mixture by simple filtration, and also recovered and reused without noticeable loss of reactivity. 2-Aryloxazolo[4,5-b]pyridines have different pharmacological activities (anti-inflammatory, anti-pyretic, analgesic, antifungal). In the current method for the synthesis of 2-aryloxazolo[4,5-b]pyridines, no hazardous organic solvent was used and simplicity of the procedure provides significant improvements over many of other existing methods. Furthermore, the SBA-15-Pr-NH2 with pore size of 6 nm can act as nano-reactor.