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A Simple Phosphine–Diolefin‐Promoted Copper‐Catalysed N‐Arylation of Pyrazoles with (Hetero)aromatic Bromides: The Case of Chloroarenes Revisited
Author(s) -
Rampazzi Vincent,
Massard Alexandre,
Richard Philippe,
Picquet Michel,
Le Gendre Pierre,
Hierso JeanCyrille
Publication year - 2012
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201200368
Subject(s) - phosphine , chemistry , aryl , ligand (biochemistry) , nucleophilic aromatic substitution , combinatorial chemistry , medicinal chemistry , nucleophile , pyrazole , copper , catalysis , organic chemistry , nucleophilic substitution , alkyl , biochemistry , receptor
Abstract A molecularly defined new phosphine–diolefin cubane copper pre‐catalyst used at 1.25 mol % under mild conditions promotes the coupling of pyrazoles to functionalised aryl and heteroaryl bromides, which hold a variety of functional groups. This versatile phosphorus‐based system was thus successfully used, under identical conditions, for the coupling of a large scope of heteroaromatics to selectively produce pyridinyl‐ and pyrimidinyl‐pyrazoles, as well as several novel furyl‐, thienyl‐ and thiazolyl‐substituted pyrazoles. The careful investigation of coupling with the analogous aryl and heteroaryl chlorides clearly indicated that for specifically activated chloroarenes a direct nucleophilic aromatic substitution (S N Ar) is easily achieved in the absence of any copper and ligand. These results are pertinent with regards to the reported protocols in which copper–ligand systems have been claimed as useful for coupling activated chloroarenes.