171364-85-5Relevant articles and documents
Iridium-catalyzed C-H coupling reaction of heteroaromatic compounds with bis(pinacolato)diboron: Regioselective synthesis of heteroarylboronates
Takagi, Jun,Sato, Kazuaki,Hartwig, John F,Ishiyama, Tatsuo,Miyaura, Norio
, p. 5649 - 5651 (2002)
The C-H coupling of aromatic heterocycles with bis(pinacolato)diboron was carried out in octane at 80-100°C in the presence of a 1/2[IrCl(COD)]2-(4,4′-di-tert-butyl-2,2′-bipyridine) catalyst (3 mol%). The reactions of five-membered substrates such as thiophene, furan, pyrrole, and their benzo-fused derivatives exclusively produced 2-borylated products, whereas those of six-membered heterocycles including pyridine and quinoline selectively occurred at the 3-position. Regioselective synthesis of bis(boryl)heteroaromatics was also achieved by using an almost equimolar amount of substrates and the diboron.
Polysulfide Anions as Visible Light Photoredox Catalysts for Aryl Cross-Couplings
Li, Haoyu,Tang, Xinxin,Pang, Jia Hao,Wu, Xiangyang,Yeow, Edwin K. L.,Wu, Jie,Chiba, Shunsuke
supporting information, p. 481 - 487 (2021/01/13)
Polysulfide anions are endowed with unique redox properties, attracting considerable attentions for their applications in alkali metals-sulfur batteries. However, the employment of these anionic species in redox catalysis for small molecule synthesis remains underdeveloped due to their moderate-poor electrochemical potential in the ground state, whereas some of them are characterized by photoabsorptions in visible spectral regions. Herein, we disclose the use of polysulfide anions as visible light photoredox catalysts for aryl cross-coupling reactions. The reaction design enables single-electron reduction of aryl halides upon the photoexcitation of tetrasulfide dianions (S42-). The resulting aryl radicals are engaged in (hetero)biaryl cross-coupling, borylation, and hydrogenation in a redox catalytic regime involving S4?-/S42- and S3?-/S32- redox couples.
Efficient Synthesis of Aryl Boronates via Cobalt-Catalyzed Borylation of Aryl Chlorides and Bromides
Verma, Piyush Kumar,Mandal, Souvik,Geetharani
, p. 4049 - 4054 (2018/05/22)
An efficient catalytic system based on a Co(II)-NHC precursor has been developed for the cross coupling of bis(pinacolato)diboron with aryl halides including aryl chlorides, affording the aryl boronates in good to excellent yields. A wide range of functional groups are tolerated under mild reaction conditions. The reaction shows excellent chemoselectivity for bromide over chloride. Preliminary mechanistic investigations show that the catalytic cycle may rely on a cobalt(I)-(III) redox couple.