Premium
Pd/C as Heterogeneous Catalyst for the Direct Arylation of (Poly)fluorobenzenes
Author(s) -
Mao Shuxin,
Shi Xinzhe,
Soulé JeanFrançois,
Doucet Henri
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201900921
Subject(s) - chemistry , bond cleavage , catalysis , aryl , trifluoromethyl , medicinal chemistry , regioselectivity , nitrile , palladium , reactivity (psychology) , bromide , ligand (biochemistry) , carbene , biphenyl , combinatorial chemistry , organic chemistry , alkyl , biochemistry , alternative medicine , receptor , medicine , pathology
The potential of the heterogeneous catalyst 10 % Pd/C in the direct arylation of (poly)fluorobenzene derivatives with aryl bromides has been investigated. In general, high yields of biaryl derivatives were obtained by using tri‐, tetra‐, and pentafluorobenzenes, whereas mono‐ and difluorobenzenes exhibited poor reactivity. The regioselectivities of the arylation reactions were similar to those observed with homogeneous palladium catalysts. Both electron‐withdrawing and ‐donating substituents, such as nitrile, nitro, acetyl, ester, trifluoromethyl, tert ‐butyl, methoxy, or methyl, on the aryl bromide were tolerated. Unexpectedly, tetrafluoro‐substituted [1,1′‐biphenyl]‐4‐ols were obtained from pentafluorobenzene at 150 °C due to a formal regioselective hydroxylation, whereas at lower temperatures the expected pentafluorobiphenyls were obtained. However, no C−F bond cleavage was observed with the other polyfluorobenzene derivatives. These arylation reactions were carried out with only 1 mol % Pd/C as the catalyst and KOAc as an inexpensive base. Therefore, this protocol represents a very attractive access to (poly)fluoro‐substituted biphenyls in terms of cost, simplicity, and sustainable chemistry because the Pd/C catalyst can be easily removed at the end of the reaction, there is no contamination with phosphine ligand residues, and the major side‐product of the reaction is KOAc ⋅ HBr.