Selective Mono-Alkylation and Arylation of Dichlorobenzenes by Palladium-Catalyzed Grignard Cross-Coupling

Abstract

Palladium(II)–phosphine complexes, especially PdCl2(dppf) where dppf stands for 1,1′-bis(diphenylphosphino)ferrocene, are effective catalysts for the cross-coupling of Grignard reagents with dichlorobenzenes to produce selectively mono-alkylated and arylated benzenes. The addition of ligands is also effective for the cross-coupling of Grignard reagents containing a β-hydrogen(s).

Advances in Transition Metal (Pd,Ni,Fe)-Catalyzed Cross-Coupling Reactions Using Alkyl-organometallics as Reaction Partners

“…411 They observed that the use of additional dppf ligand gave better results for reactions with alkyl Grignard reagents. It was postulated that the additional ligand blocks the open coordination site on Pd.…”

Palladium-Catalyzed Coupling Reactions of Aryl Chlorides

“…Thus, selective monocoupling of dichlorobenzenes with aryl and alkyl Grignard reagents can be achieved with [PdCl 2 (dppf)] as the catalyst [Eq. (35)]; in all cases, less than 5 % of the dialkylated product is observed 155. Uemura et al have noted that tricarbonyl( η 6 ‐chloroarene)chromium complexes participate in Kumada couplings, although dehalogenation is a significant side reaction 27a…”

“…(35)]; in all cases, less than 5 % of the dialkylated product is observed. [155] Uemura et al have noted that tricarbonyl(h 6chloroarene)chromium complexes participate in Kumada couplings, although dehalogenation is a significant side reaction. [27a] The first report of a palladium-catalyzed Kumada crosscoupling of an unactivated aryl chloride was provided by Herrmann et al, who showed that palladacycles accomplish the coupling of chlorobenzene with MeMgBr and PhMgCl.…”

Palladiumkatalysierte Kupplungen von Arylchloriden

“…Auf diese Weise können selektive Einfachkupplungen von Dichlorbenzolen mit Aryl‐ und Alkyl‐Grignard‐Reagentien mit [PdCl 2 (dppf)] als Katalysator erzielt werden [Gl. (35)]; in allen Fällen erhält man weniger als 5 % des dialkylierten Produkts 155. Uemura et al haben berichtet, dass Tricarbonyl(η 6 ‐chloraren)chromkomplexe an Kumada‐Kupplungen beteiligt sein können, obgleich die Dehalogenierung als Nebenreaktion einen bedeutenden Umfang annimmt 27a…”