An efficient and one-pot synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed via solid acid nano-catalyst

A simple highly versatile and efficient synthesis of 2,4,5-trisubstituted imidazoles is achieved by three component cyclocondensation of 1,2-dicarbonyl compounds, aldehydes and NH4OAc, as ammonia source using clays, zeolite, nano-crystalline sulfated zirconia (SZ) as catalyst in ethanol at moderate temperature. Moreover, the utility of this protocol was further explored conveniently for the one-pot, four component synthesis of 1,2,4,5-tetrasubstituted imidazoles in high yields, short reaction times and milder conditions, easy work-up and purification of products by non-chromatographic methods. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of their efficiency.

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• A one-pot, multicomponent methodology has been developed for the synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles catalyzed by clays, zeolite and nano-crystalline SZ as catalyst in high yields.
• Compared to previously reported methods, Moreover, the mild reaction conditions, easy work-up, clean reaction profiles, lower catalyst loading and cost efficiency render this approach as an interesting alternative to the existing methods.
• The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of their efficiency.