This method reports a high-yield synthesis of 2-hydroxy diaryl ureas from benzoxazoles, suggesting operational simplicity and broad substrate applicability.
A efficient method for synthesizing asymmetric 2-hydroxy diaryl ureas has been developed via phenyliodine bis(trifluoroacetate) (PIFA)-mediated ring-opening/coupling of benzoxazoles with aryl isocyanates or isothiocyanates. This transition-metal-free protocol operates under mild conditions and utilizes Al2O3/H+ as a key additive, achieving high yields (up to 95%) with broad substrate scope. The reaction proceeds through a proposed PIFA-induced ring-opening of benzoxazole followed by nucleophilic addition, providing direct access to pharmacologically and materially valuable 2-hydroxy diaryl ureas while avoiding toxic reagents and high-pressure equipment. This strategy addresses limitations of traditional urea syntheses, offering operational simplicity and scalability.
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Xia et al. (2025) studied this question.
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