Background: The development of efficient methodologies for the preparation
of benzoxazole and its derivatives has gained a lot of importance in current research.
There are many methods are reported for the synthesis of benzoxazoles includes
condensation of 2-aminophenol with carboxylic acid. Traditional methods also
have several side reactions, non renewable oxidative reagents and solvents which negatively
affect the environmentally and eco-friendly nature of the reaction. We have developed
PTA catalyzed synthesis of 2-arylbenzoxazole from 2-aminophenols with different
aromatic aldehydes using a grinding strategy in excellent yield.
Methods: The synthesis of benzoxazoles in high yields by using silica supported
PTA/PTA as solid acid catalyst at room temperature using grinding method.
Results: Aromatic aldehydes which have electron donating or electron withdrawing groups were also
investigated and as expected it gives good to excellent yield of products, it can be seen that electron donating
and electron withdrawing groups does not show any difference on their action yields.
Conclusion: We have developed PTA catalyzed synthesis of 2-arylbenzoxazole from 2-aminophenols
with different aromatic aldehydes using a grinding strategy in excellent yield. The use of this reusable
catalyst under solvent-free conditions has made this protocol practical, environmentally friendly and
economically attractive. The simple work-up procedure, the short reaction times the mild reaction conditions,
the high yields of products and the non-toxicity of the catalyst are other advantages of the present
method. This protocol approaches combines the advantages of both focused library synthesis and diversity
oriented synthesis because of the simplification of reaction protocol that we have been developed.