Nickel cross-coupling

In Chap. 6, a companion to the preceding chapter, Li and Gribble document Metal-Catalyzed Cross-Coupling Reactions for Indoles , which covers palladium, copper, rhodium, iron, and nickel cross-couplings of indole - a suite of reactions that has assumed great importance in indole synthesis and chemistry. 

Kozuch, S. Lee, S. E. Shaik, S. Theoretical analysis of the catalytic cycle of a Nickel cross-coupling process Application of the energetic span model. Organometallics 2009,28, 1303-1308. 

Nickel (II) Catalyzed Cross-Coupling with Grignard Reagents (Kumada Reaction) Pure AppJ. Chem. 1980, 52, 669 Bull Chern. Soc.Jpn. 1976, 49, 1958... 

Alkyl- and aryl-pyridazines can be prepared by cross-coupling reactions between chloropyridazines and Grignard reagents in the presence of nickel-phosphine complexes as catalysts. Dichloro[l,2-bis(diphenylphosphino)propane]nickel is used for alkylation and dichloro[l,2-bis(diphenylphosphino)ethane]nickel for arylation (78CPB2550). 3-Alkynyl-pyridazines and their A-oxides are prepared from 3-chloropyridazines and their A-oxides and alkynes using a Pd(PPh3)Cl2-Cu complex and triethylamine (78H(9)1397). 

Modem cross coupling chemistry is heavily dominated by the use of palladium and nickel complexes as the catalysts, which show an impressively wide scope and an excellent compatibility with many functional groups.2 This favorable application profile usually overcompensates the disadvantages resulting from the high price of the palladium precursors, the concerns about the toxicity of nickel salts, the need for ancillary ligands to render the complexes sufficiently active and stable, and the extended reaction times that are necessary in certain cases. 

The C-C bond forming reaction of an organic halide with an organosilane, catalysed by nickel or palladium, is known as the Hiyama cross-coupling. Typically the C-Si bond needs to be activated by either electronegative substituents or by external fluoride anions. 

Hydroboration of alkenes or alkynes followed by cross-coupling with organic electrophiles provides a straightforward method for the carbon-carbon bond formation (Scheme 1-19). The hydroboration of thioalkynes with catecholborane in the presence of a nickel or palladium catalyst yields P-(aLkylthio)-l-alkenylboronates (72a)... 

Similarly, nickel catalysis permits the extension of cross coupling to vinyl phosphates, which are in some cases more readily obtained and handled than vinyl triflates.273... 

Optically active amine-thioether ligands (492) have been investigated in nickel-catalyzed asymmetric cross-coupling reactions of Grigard reagents.1338... 

Activated aryl chlorides, which are close in reactivity to unactivated aryl bromides, underwent reaction with the original P(o-tol)3-ligated catalyst.58 Nickel complexes, which catalyze classic C—C bond-forming cross-couplings of aryl chlorides, 9-64 also catalyzed aminations of aryl chlorides under mild conditions.65,66 However, the nickel-catalyzed chemistry generally occurred with lower turnover numbers and with a narrower substrate scope than the most efficient palladium-catalyzed reactions. 

Nickel-bpy and nickel-pyridine catalytic systems have been applied to numerous electroreductive reactions,202 such as synthesis of ketones by heterocoupling of acyl and benzyl halides,210,213 addition of aryl bromides to activated alkenes,212,214 synthesis of conjugated dienes, unsaturated esters, ketones, and nitriles by homo- and cross-coupling involving alkenyl halides,215 reductive polymerization of aromatic and heteroaromatic dibromides,216-221 or cleavage of the C-0 bond in allyl ethers.222... 

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

Cross-coupling reactions of vinyl zirconocenes of general structure 41, mainly using group 10 metal catalysts, can be smoothly effected to give a variety of vinyl selenide-con-taining materials, which are amenable to further elaboration through nickel-catalyzed... 

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