Reactivity of mixed organozinc and mixed organocopper reagents: 11. Nickel-catalyzed atom-economic aryl-allyl coupling of mixed (n-alkyl)(aryl)zincs

Group selectivity in the allylation of mixed (n-butyl)(phenyl) zinc reagent can be controlled by changing reaction parameters. CuCN-catalyzed allylation in tetrahydrofuran (THF)-hexamethylphosphoric triamide is n-butyl selective and also gamma-selective in the presence of MgCl2, whereas CuI-catalyzed allylation in THF in the presence of n-Bu3P takes place with a n-butyl transfer:phenyl transfer ratio of 23:77 and an alpha:gamma transfer ratio of phenyl of 76:24. NiCl2(Ph3P)(2)-catalyzed allylation in the presence of LiCl is phenyl selective with an alpha:gamma ratio of 65:35. The reaction of methyl-or n-butyl(aryl) zinc reagents with an allylic electrophile in THF at room temperature in the presence of NiCl2(Ph3P)(2) catalyst and LiCl as an additive provides an atom-economic alternative to aryl-allyl coupling using diarylzincs. Copyright (C) 2014 John Wiley & Sons, Ltd.