The application of a synthetic sequence of amine-exchange/Ullmann-ether reaction to 1,2-diarylenamino-ketones for the access to dibenzoxepino[4,5-d]pyrazoles is reported. The reaction proceeds efficiently, permitting to incorporate a variety of substituents. (C) 2000 Elsevier Science Ltd. All rights reserved.
A novel palladium intramolecular diaryl ether formation
This paper presents an efficient methodology for the preparation of dibenzoxepino[4,5-d]pyrazoles using a novel intramolecular palladium catalyzed diaryl ether formation. The effect of different chelating ligand systems, along with the unusual coupling reaction of phenoxides with aryl iodides and non-activated aryl moieties are also reported. (C) 2000 Elsevier Science Ltd. All rights reserved.
Revisiting the Ullmann−Ether Reaction: A Concise and Amenable Synthesis of Novel Dibenzoxepino[4,5-<i>d</i>]pyrazoles by Intramolecular Etheration of 4,5-(<i>o,o</i>‘-Halohydroxy)arylpyrazoles
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 substituents. The synthesis of the key o,o'-halohydroxy-4,5-diarylpyrazole intermediates proceeds through the construction of the heterocyclic ring by a tandem amine-exchange/heterocyclization sequence of 3-N,N-(dimethylamino)-1