Homocoupling of aryl halides promoted by an NiCl₂/bpy/Mg system in DMF

Abstract

Homocoupling of aryl halides (2 ArX → Ar-Ar) promoted by NiCl 2 /2,2′-bipyridine (bpy)/Mg mixtures in DMF has been studied. Mixtures of NiCl 2 , bpy and Mg in DMF promoted homocoupling of aryl halides such as phenyl bromide and p-tolyl bromide to give the coupling products in good (e.g. approximately 60-75%) yields, and the homocoupling products were easily isolated from the reaction mixtures. Application of this homocoupling to dibromo-aromatic compounds (Br-arylene-Br: 2,5-dibromopyridine, 2,7-dibromo-9.9-dioctylfluorene and 2,7-dibromo-9,10-dioctyl-9,10-dihydrophenanthrene) gave the corresponding π-conjugated polymers, -(arylene) n -, in good yields. Organometallic processes for the homocoupling are discussed.

Rational design of new in situ reduction of Ni(II) catalytic system for low‐cost and large‐scale preparation of porous aromatic frameworks

“…29,32 The detailed dehalogenation coupling mechanism in the presence of NaI is shown in Figure 2A. In contrast to the NiCl 2 /bpy/Mg system previously reported, 26,27 the addition of NaI can induce halogen exchange reaction between aryl halides and iodide ions (the possible active Ni complexes are shown in Figure 2B). 33,34 The specific possible halogen exchange reactions are shown in Figure 2C.…”

“…In 2012, the Ni(II)/bpy/Mg catalyst system was reported by Professor T. Yamamoto for dehalogenation coupling reaction of linear aryl halides, where Mg acts as a reducing agent and N,N-dimethylformamide (DMF) serves as a polar solvent. 26,27 This in situ reduction of Ni(II) precursors via Mg can deliver active Ni(0) species, followed by the oxidative addition of aryl halide and Ni (0)-bpy complex, disproportionation reaction of aryl nickel (II) intermediate, and reductive elimination of diaryl Ni-complex to form coupling products (eq1-eq5 in Supporting Information). However, when the same reaction condition was applied for PAF-1 synthesis, gellike solids with very low specific surface area were obtained.…”

HF Resistant Porous Aromatic Frameworks for Electronic Special Gases Separation

“…Porous aromatic framework-1 (PAF-1) as an emerging robust covalently bond linked porous material is consider as the excellent candidate adsorbent that can resistant to harsh environments such as strong acids, strong bases and high temperature. , Due to the expensive catalysts and cumbersome operations in the PAF-1 synthesis system­(Ni­(COD) 2 /COD/bpy catalyst system), here we adopted an in situ reduction of Ni­(II) catalyzed coupling polymerization − to synthesize well-known porous aromatic framework (named New-PAF-1). The active Ni(0) species produced from NiCl 2 /bpy/Mg catalyst system can effectively catalyzed homocoupling of tetra­(4-bromophenyl)­methane at room temperature to give New-PAF-1 with BET specific surface area up to 4076 m 2 g –1 (Langmuir surface area, 5206 m 2 g –1 ).…”

Oxidative and Reductive Cross-Coupling Reactions Catalyzed by an Anionic “Ligandless” Palladium Complex

“…Among the most straightforward and well-established methods are palladium-catalyzed cross-coupling reactions. − While the Mizoroki–Heck reaction allows access to stilbenes (Scheme a), − the Suzuki–Miyaura reaction, among others, yields biphenyls (Scheme b). − However, most of these cross-coupling reactions suffer from low atom economy and the necessity to use toxic, air-sensitive organometallic reagents. − Among the required aryl halides, aryl chlorides are the reaction partners of choice since they are less expensive, but on the other side, they are also less reactive. One approach to attenuate these drawbacks is the development of the oxidative Heck reaction − of a boronic acid (as a surrogate for the aryl halide) and an alkene for the synthesis of stilbenes (Scheme a). − A viable alternative for the synthesis of symmetric biphenyls is the reductive homodimerization of aryl halides (Scheme b). − …”