Improed process for coupling arylboronic acids with aryl halides - carried out in presence of a transition metal (esp. palladium) catalyst with a bidentate, lipophilic, aliphatic phosphine ligand

摘要

An improved method for carrying out a cross-coupling reaction comprises performing the reaction in the presence of a transition metal catalyst contg. a lipophilic, aliphatic phosphine ligand of formula (R1)2-P-R2 (I) or also a gp. of formula -R3-P(R1)2 (II) R1 = 1-6C alkylor alkoxy, or 4-8C cycloalkyl or cycloalkoxy, pref. 3-6C alkyl, 3-6C alkoxy or cyclohexyl; R2 = as for R1; R3 = 1-20C alkylene. Also claimed is a process for the prodn. of bis-aryl cpds. (III) in the presence of a catalyst contg. (I). Also claimed is 2,6-difluoro-4-chloro-trifluoromethoxy-benzene (VI). USE/ADVANTAGE - The process provides an improved method for carrying out the above coupling reaction, which can be performed on a large scale with little risk and low cost, esp. for the prodn. of F-substd. biphenyl derivs. with mesogenic gps., using (VI) as coupling component. The process is carried out at readily accessible temps. from readily available starting materials, and gives (III) in high yield (contrast conventional coupling catalysts).