Alkylation cross-coupling

Cardenas, D. J. Towards efficient and wide-scope metal-catalyzed alkyl—alkyl cross-coupling reactions. Angew. Chem. Int. Ed. 1999,... 

Alkyl halides other than aryl and vinyl halides do not readily undergo oxidative addition with Pd and must, in general, first be converted to alkylmetals. In this connection, however, a recent report on the Ni catalysed selective alkyl-alkyl cross-coupling with Ni(acac)2 and Lil in THF represents a significant breakthrough.34 In cases where the alkyl group contains a p-H atom, reduction of the organic halide via p-dehydropalladation reductive elimination can be a serious side-reaction (Scheme 11.6). 

Fig. 12. Two-electron mechanisms proposed by TAMREAC for the allyl-alkyl cross-coupling. The two numbers below each complex correspond to the complex number and to the valence electron number, respectively. Numbers in parentheses by the arrows correspond to the reaction numbers (Tables II, III, and IV). R = alkyl, X = halide, L = solvent molecule.

Fig. 13. One-electron nonchain mechanisms proposed by TAMREAC for the allyl—alkyl cross-coupling.

Fig. 40 Alkyl-alkyl cross-coupling reactions catalyzed by Pd(0) complexes...

It has also been found that nickel-terpyridyl catalytic systems enable alkyl-alkyl cross-coupling with alkylzinc halides only using THF as solvent (Scheme 4.98) [299]. For instance, nPentZnBr undergoes coupling at rt and in excellent yields with 3-phenylpropyl iodide 425 in the presence of Ni(COD)2 (5 mol%) and tBu-Terpy (277) (5mol%). These catalytic systems have been studied in detail from... 

Alkyl-alkyl cross-coupling reactions have historically been the most difficult to realize. Among the many obstacles to the effective development of such a system are the lower reactivity of alkyl groups relative to alkenyl and aryl groups, as well as side processes such as -hydride elimination that are accessible with alkyl substrates. More reports by Fu et al. have disclosed successful alkyl cross-coupling protocols... 

A series of arylynamides with alkyloxy groups at the ortho position of the aryl group has been prepared by an alkylation/cross-coupling/amidation sequence and a subsequent gold-catalysed reaction provides benzofurans with amine functionalities at the 2-position and alkyl groups at the 3-position. The mechanism of gold(III)-catalysed isomerization of alkyl-substituted allenes to conjugated dienes in the presence of a... 

Scheme 2-31. Alkyl-alkyl cross-coupling reaction catalyzed by Cu(l)-salts.

Of-Silylalkanenitriles couples with aryl halides to give a variety of cx-arylalkanenitriles (Scheme 3-169). On the other hand, alkyl cross-coupling reaction using alkylsilane reagents as nucleophiles is successful only with... 

Ishiyama T, Abe S, Miyaura N, Suzuki A. Palladium-catalyzed alkyl-alkyl cross-coupling reaction of 9-Alkyl-9-BBN derivatives with iodoalkanes possessing (i-hydrogens. Chem. Lett. 1992 21(4) 691-694. 

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