Halides nickel-catalyzed coupling

In 1979, the reaction of styrenyl and hexenyl halides with an alkali metal thiophenolate and ethanethiolate was reported (Equation (40))130 Reaction yields exceeded 90%, and the products retained the geometry of the starting olefin. In contrast to the stereospecificity of palladium-catalyzed couplings involving vinyl halides, nickel-catalyzed couplings of vinyl halides with thiolates gave mixtures of stereoisomeric products 131... 

Scheme 72 Nickel-catalyzed coupling of aryl halides and alkenes.

The synthesis involves the nickel-catalyzed coupling of the mono-Grignard reagent derived from 3-alkyl-2,5-diiodothiophene (82,83). Also in that year, transition-metal halides, ie, FeQ3, MoCb, and RuCl3, were used for the chemical oxidative polymerization of 3-substituted thiophenes (84). Substantial decreases in conductivity were noted when branched side chains were present in the polymer structure (85). 

In the area of organometallic chemistry, we begin with a procedure for the palladium-catalyzed animation of aryl halides and aryl triflates, illustrated by syntheses of N-HEXYL-2-METHYL-4-METHOXYANIUNE and N-METHYL-N-<4-CHLOROPHENYL)-ANILINE. The next procedure describes the synthesis of 1,2,3,4-TETRAHYDROCARBAZOLE by the palladium-catalyzed annulation of ketones with o-iodoaniline. Next, a procedure for the synthesis of 2,7-DIMETHYLNAPHTHALENE via the nickel-catalyzed coupling of aryl O-carbamates with Grignard reagents is presented. The fourth procedure in this section describes the synthesis of 5-METHYL-2,2 -BIPYRIDINE by a Negishi cross-coupling reaction... 

Palladium or nickel-catalyzed coupling of organoboron compounds with unsaturated halides or triflates. 

Boldrini, G.P., Savoia, D., Tagliavini, E. et al. (1986) Nickel-catalyzed coupling of activated alkenes with organic halides. J. Organomet. Chem., 301, C62-4. 

CO insertion prior to the transmetallation step. The mechanism of nickel-catalyzed coupling reactions is less established. Early studies indicated that homocoupling processes occur by oxidative addition through radical intermediates and possible intermediacy of Ni(I) and Ni(III) complexes. The copper-catalyzed cross-coupling reactions likely occur by transmetallation prior to oxidiative addition of the aryl halide. Iron-catalyzed reactions likely occur by low-valent, even sub-valent, species. 

A genuine coupling based on a group 10 M(11)/M(1V) catalysis is probably involved in the nickel-catalyzed coupling of alkyl halides and tosylates with the Grignard reagents discovered by Kambe (Scheme 1.22) [206]. A similar system has... 

Nickel-Catalyzed Coupling of Arenes with Alkyl Halides.129... 

SCHEME 5.42 Sequential selective nickel-catalyzed couplings of alkynes with difunctional alkyl halides. 

Thiophene derivatives represent a good example of how color of emission can be varied in PLEDs by modifying the polymer structure. Fig. 15 [95-99]. Soluble poly (3-alkylthiophene)s have been prepared by polymerization of 3-alkylthiophene monomers in the presence of excess ferric chloride, or by nickel-catalyzed coupling of dihalothiophenes with thiophene-bis(magnesium halide)s [100, 101]. 

SCHEME 4.243 Nickel-catalyzed coupling of secondary phosphites with aryl halides [336]. 

Organozinc reagents are superior species for palladium- and nickel-catalyzed coupling reactions. This offers an exceptional method for the selective formation of sp -sp (eq 5), sp -sp (eqs 6 and 7), and sp -sp (eq 8) carbon-carbon bonds. In addition, the palladium-catalyzed coupling reactions of sp and sp halides with vinylalanes (eq 9), vinylcuprates, vinylzirconium (eq 10) and acyliron species often proceed more effectively in... 

The palladium-catalyzed formation of sulfides can generate polyphenylene sulfide from a dithiol and a dibromoarene, or from 4-bromobenzenethiol (Equation (38)).17 In 1984 Asahi Glass obtained patents for the formation of this polymer in the presence of palladium and nickel catalysts.125,126 In addition, Gingras reported palladium-catalyzed couplings of aryl halides and thiols to form discrete phenylene sulfide oligomers.127,128 A number of polyphenylene sulfide wires, ranging from dimeric to pentameric structures, were prepared by the palladium coupling, albeit in modest yields ... 

Although more hydrolytically sensitive than the phosphine boranes, diorganochlorophosphines can be more accessible than diorganophosphines and are not pyrophoric. Thus, the reaction of a chlorophosphine with an aryl halide or aryl triflate in the presence of zinc as a reducing agent and (DPPE)NiCl2 as catalyst provides a convenient procedure for P—C coupling (Equation (49)).150 A related nickel-catalyzed process driven by electrochemical reduction has also been reported 151... 

The presence of a remote C=C double bond in the alkyl halide was critical saturated analogs underwent nickel-catalyzed halogen-zinc exchange.248 It has been suggested that the double bond coordinates to the nickel atom. As a 7r-acceptor, the C=C bond removes some electron density from the metal, thus facilitating the reductive coupling (Scheme 154).246... 

Scheme 6.44 Nickel-catalyzed cross-coupling of zirconocenes and aryl halides.

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