Abstract
A nickel-catalyzed cross-coupling reaction between aryltitanium(IV) alkoxides and various functionalized aryl halides is described. The reaction requires Ni(acac)2 (0.5 mol%), a phosphine or an N-heterocyclic carbene ligand (NHC ligand; 0.5-1.0 mol%) and proceeds at 25 °C within 1-24 hours.
Key words
organotitanium reagents - cross-coupling - nickel
References and Notes
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Typical Procedure for the Cross-Coupling Reaction; Preparation of Biphenyl-4-carboxylic Acid Ethyl Ester (
3a) : A flame-dried flask equipped with a magnetic stirring bar, an argon inlet, and a septum was charged with a Ti(OEt)4 solution (1.0 mL, 1.5 M in THF). First phenyl-magnesium chloride (0.84 mL, 1.79 M in THF) was added dropwise at 0 °C, then Ni(acac)2 (1.3 mg, 0.005 mmol), ligand 4 (2.1 mg, 0.005 mmol) and 4-bromobenzoic acid ethyl ester (2a ; 229 mg, 1.00 mmol) were added. The reaction mixture was stirred for 3 h at r.t. Then the mixture was quenched with a sat. NH4 Cl solution and extracted with Et2 O. Column chromatography (pentane-Et2 O, 9:1) of the crude residue yielded 3a as colorless solid (215 mg, 95%).
