Oxone®-mediated Dakin-like reaction to synthesize hydroxyarenes: an approach using pyrazolo[1,5-a]pyrimidines

A simple and efficient methodology was developed for converting formyl(hetero)arenes into the corresponding hydroxylated derivatives in high yields (95-99%) using Oxone® as the oxidant. This Dakin-like reaction proceeded via C-C bond cleavage with the insertion of an oxygen atom into the formyl group, forming the corresponding formyl esters (up to 99%), which then underwent basic hydrolysis to yield the desired alcohols. Although the substrate scope mainly included 3-hydroxypyrazolo[1,5-a]pyrimidines, other substrates featuring typical fluorophores (e.g., triphenylamine, anthracene, pyrene, fluorene, and coumarin) were also tested. Moreover, we demonstrated the functionalization of the representative 3-hydroxypyrazolo[1,5-a]pyrimidine derivatives obtained using our developed methodology involving alkylation, acylation, and sulfonylation reactions.