Modified cobalt(II) acetylacetonate complexes as catalysts for Negishi-type coupling reactions: influence of ligand electronic properties on catalyst activity

Abstract

Four known electronically diverse cobalt(II) acetylacetonate derivatives were synthesized by replacement of the acetylacetonate methyl groups with combinations of tert-butyl, ethoxy, and trifluoromethyl groups in order to study the effect of catalyst electronic properties on the reaction rate and product yield of the cobalt-catalyzed reaction between haloalkenes and butylzinc iodide. Infrared spectroscopy of these compounds showed an increase in the CO stretching frequency as the ligand substituents became more electron withdrawing. These compounds, in addition to cobalt(II) acetylacetonate itself, were evaluated as catalysts for the coupling reaction between (E)-1-iodo-1-octene and butylzinc iodide to form (E)-5-dodecene. Faster reaction rates were observed and higher yields of 5-dodecene were produced when catalysts containing electron-donating ligands were employed. Side reactions, including the homocoupling of 1-iodo-1-octene to produce 7,9-hexadecadiene, were also observed under the reported reaction conditions. The rate of side-product formation was more competitive with the rate of the cross-coupling reaction when slower, electron-deficient catalysts were employed.

Cobalt-Catalyzed Vinylation of Aromatic Halides Using β-Halostyrene: Experimental and DFT Studies

“…These last reactions have been extensively studied with palladium- or nickel-based catalysts, involving a vinyl halide and an aryl metal compound or conversely an aryl halide and a vinyl metal compound . Some other catalysts were used with success: rhodium, iron, manganese, and cobalt especially. All of the reactions described above deal with the synthetic difficulties associated with the preparation of the organometallic reagent especially when its organic precursor bears a reactive group.…”

Highly efficient and green oxidation of alkanes and alkylaromatics with hydrogen peroxide catalysed by silver and vanadyl on mesoporous silica‐coated magnetite

“…Over the past decade, metal acetylacetonate complexes have emerged as versatile catalysts for a broad range of industrially and academically interesting reactions . Vanadyl (IV) acetylacetonate ([VO(acac) 2 ]) is a typical efficient catalyst extensively employed for various oxidative transformations .…”

Synthesis of Sterically Hindered β-Diketones via Condensation of Acid Chlorides with Enolates

“…Over the last 50 years, acetylacetonate (acac)-supported catalysts have proven capable of forming C–C bonds (via iron, − cobalt, nickel, , and copper − ), C–N bonds (via iron, cobalt, nickel, and copper), and C–O bonds (via iron, cobalt, , nickel, and copper) to highlight select metals. These examples illustrate the generality of late, first-row metal catalysis using β-diketonates in carbon bond-forming reactions, which have developed in parallel to the second- and third-row transition-metal catalysis.…”

“…The crude material is purified by trituation in acetone and obtained as an off-white powder (0.52 g, 65%): mp 220. 5 (11). To an oven-dried, 20 mL vial equipped with a stirbar and vial cap are charged sodium 1-tert-butylethenolate (1.94 g, 10 mmol), 2,6-bis(2,4,5-trimethylphenyl)benzoyl chloride (1.13 g, 3 mmol), and toluene (7.5 mL).…”

“…A second crop is obtained from the filtrates (716 mg, 54%): mp 98. 5 (12). To an oven-dried, 100 mL, one-neck roundbottom flask equipped with a stirbar and septum are charged sodium 1-tert-butylethenolate (3.89 g, 20.1 mmol), 2,6-bis(2,4,6triisopropylphenyl)benzoyl chloride (2.73 g, 5 mmol), and toluene (30 mL).…”