Metal-free oxidative decarbonylative coupling of aromatic aldehydes with arenes: direct access to biaryls
作者:Ren-Jin Tang、Qing He、Luo Yang
DOI:10.1039/c4cc10155c
日期:——
A metal-free oxidative decarbonylative coupling of aromatic aldehydes with electron-rich or electron-deficient arenes to produce biaryl compounds was developed. This novel coupling was proposed to proceed via a non-chain radical homolytic aromatic substitution (HAS) type mechanism, based on the substrate scope, ortho-regioselectivity, radical trapping experiments and DFT calculation studies. With the
Process for the preparation of unsymmetric biaryl compounds
申请人:Bayer Aktiengesellschaft
公开号:US04990647A1
公开(公告)日:1991-02-05
Unsymmetric biaryl compounds are prepared by coupling two different halogenoaromatics by reaction with a metal and carrying out the reaction in the presence of catalytic amounts of a nickel compound, a promoter and a phosphorus-containing ligand.
In this paper we report the first cross-coupling reaction of Ar3Bi with Ar'X mediated by Pd-NHC complexes by keeping the ability of Ar3Bi to transfer the three aryl moieties. Investigations were carried out in order to minimize the quantity of the side product Ar-Ar coming from the conversion of Ar3Bi. The results showed that PEPPSI IPr was a good catalyst precursor. Efforts were focussed on the rule of each additive such as PPh3 and the base. It was notably found that the presence of PPh3 (ratio PEPPSI IPriPPh(3): 1/1) was essential to keep the process efficient. Therefore NHC-Pd-PPh3 has been assumed as being the catalytic species. Under the optimized reaction conditions the concomitant formation of the undesired biaryl side product was restricted to its inherent formation consecutive to the reduction of the catalyst precursor to Pd(0). In a last study, the scope and the limitation of the new catalytic methodology were examined and a large range of unsymmetrical biaryl compounds Ar-Ar' bearing various substituents from strongly electron-donating to electron-withdrawing ones have been prepared and fully characterized. (C) 2016 Elsevier B.V. All rights reserved.
Efficient Cobalt-Catalyzed Formation of Unsymmetrical Biaryl Compounds and Its Application in the Synthesis of a Sartan Intermediate