Revisiting the Ullmann-ether reaction: A concise and amenable synthesis of novel dibenzoxepino [4, 5-d] pyrazoles by intramolecular etheration of 4, 5-(o, o'- …
A concise synthesis of a series of novel dibenzoxepino [4, 5-d] pyrazoles was accomplished by implementation of an intramolecular Ullmann-ether reaction on o, o'-halohydroxy-4, 5- diarylpyrazoles mediated by CuBr⊙ DMS. An alternative useful approach based on the palladium-catalyzed biaryl-ether linkage formation (Buchwald-Hartwig reaction) was also successfully applied, offering limitations with regard to the steric demand of the ...
