A Novel Method for the Preparation of Acid-Sensitive Epoxides from Olefins with the Combined Use of Molecular Oxygen and Aldoacetal Catalyzed by a Cobalt(II) Complex

Yorozu, Kiyotaka; Takai, Toshihiro; Yamada, Tohru; Mukaiyama, Teruaki

doi:10.1246/bcsj.67.2195

Cited by 28 publications

(9 citation statements)

References 21 publications

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“…For example, when 60 μmol of 1 was dissolved in 1 mL of neat cyclohexene and allowed to stand at room temperature for 15 h, cyclohexene oxide ( E , 9%), 2-cyclohexen-1-ol ( A , 76%), 2-cyclohexen-1-one ( K , 81%) , and tert -butyl-2-cyclohexenyl-1-peroxide ( P , 31%) were obtained. Mukaiyama and co-workers have shown that, in the presence of aldehydes, [Co(β-diketonate) 2 ] complexes epoxidize olefins selectively and in good yields . We therefore decided to attempt the epoxidation reaction by the present complexes in the presence of aldehydes.…”

Section: Resultsmentioning

confidence: 99%

Syntheses and Stuctures of Alkyl Peroxo Adducts of β-Diketonate Cobalt(III) Complexes and Their Role in Oxidation of Hydrocarbons and Olefin Epoxidation

et al. 1999

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To assess the oxidizing capacity of [Co( -diketonate) 2 (L)OOR] complexes, four such species, namely, [Co-(acac) 2 (L)(OO t Bu)] (acacH ) acetylacetone; L ) pyridine (py) (1), 4-methylpyridine (4-Mepy) (2), 1-methylimidazole (1-MeIm) (3)) and [Co(dbm) 2 (py)(OO t Bu)] (4, dbmH ) dibenzoylmethane), have been synthesized and the structures of 1, 3, and 4 have been determined by X-ray crystallography. Complex 1 crystallizes in the triclinic space group P1 h with a ) 9.149(2) Å, b ) 9.741(2) Å, c ) 13.067 (2) Å, R ) 84.22 (2)°, ) 77.89(2)°, γ ) 67.83(2)°, V ) 1054.1(4) Å 3 , and Z ) 2. Complex 3 crystallizes in the monoclinic space group P2 1 /n with a ) 11.341(2) Å, b ) 10.485(2) Å, c ) 18.863(2) Å, R ) 90°, ) 106.230(15)°, γ ) 90°, V ) 2153.6(8) Å 3 , and Z ) 4. Complex 4‚1.5C 6 H 6 crystallizes in the monoclinic space group P2 1 /c with a ) 14.907(5) Å, b ) 18.701-(5) Å, c ) 15.207(4) Å, R ) 90°, ) 103.52 (2)°, γ ) 90°, V ) 4122(2) Å 3 , and Z ) 4. The geometry around the Co(III) center in all four complexes is distorted octahedral, and the two -diketonate ligands are cis to each other. The Co-O and O-O bond distances in the Co-OO t Bu moiety fall in the narrow ranges of 1.860(3)-1.879 (2) and 1.451(3)-1.466(3) Å, respectively. Although stable in the solid state, these complexes decompose in benzene or halocarbon solutions to afford t BuOO • and t BuO • radicals. When alkanes like cyclohexane are present in the reaction mixture, these radicals initiate oxidation of the C-H bond. The oxidizing capacity follows the order 1 > 2 > 3 > 4. Decomposition of the complexes in the presence of cyclohexene and an aldehyde results in selective epoxidation in high yield.

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Section: Resultsmentioning

confidence: 99%

Syntheses and Stuctures of Alkyl Peroxo Adducts of β-Diketonate Cobalt(III) Complexes and Their Role in Oxidation of Hydrocarbons and Olefin Epoxidation

et al. 1999

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“…Oxidation of Silyl Enol Ethers. Oxidation of silyl enol ethers using various oxidants has been investigated for the synthesis of α-hydroxy carbonyl compounds. − For example, the oxidation of silyl enol ethers with m -CPBA followed by treatment with an acid or a base is a general high-yielding method for the specific α-hydroxylation of ketones 4a…”

Section: Resultsmentioning

confidence: 99%

“…There are many reports on the transformation of enol ethers such as vinyl and silyl enol ethers to α-hydroxy carbonyl compounds. − However, little has been published on the oxidation of enol ethers using aqueous hydrogen peroxide as an oxidant, probably because the enol ethers are assumed to be easily hydrolyzed in an aqueous medium. Hydrogen peroxide is one of the most useful oxidants which does not produce any waste except for water; therefore, if aqueous hydrogen peroxide can be applied to such oxidation, this method provides a new facile approach to preparation of α-hydroxy carbonyl compounds which are important precursors for natural product synthesis …”

Section: Introductionmentioning

confidence: 99%

Selective Oxidation of Vinyl Ethers and Silyl Enol Ethers with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate

et al. 1997

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The oxidation of vinyl and silyl enol ethers with aqueous hydrogen peroxide was first achieved by the use of peroxotungstophosphate (PCWP) as the catalyst. For example, the oxidation of 1-ethoxy-1-octene with a stoichiometric amount of 35% H(2)O(2) in the presence of PCWP (0.5 mol %) in a mixed solvent of methanol and dichloromethane at room temperature gave 1-ethoxy-1-methoxy-2-hydroxyoctane, a synthetic equivalent of 2-hydroxyoctanal, in 70% yield. The oxidation of acyclic silyl enol ethers such as 1-[(trimethylsilyl)oxy]-1-octene under these conditions gave 1-hydroxy-2-octanone in 72% yield, while the same oxidation in dichloromethane alone resulted in cleavage of the enol double bond to form heptanal in 71% yield. Cyclic silyl enol ethers were converted into the corresponding alpha-hydroxy ketones in 48-71% yields under similar reaction conditions.

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“…The reaction occurs for many other alkenes using transition metals coordinated to 1,3-diketone type ligands 31 34 . Use of a cobalt(II) complex and aldoacetal in place of the Mn(III) compound and pivaldehyde gives a novel method for the synthesis of acid-sensitive epoxides 35 .…”

Section: A Epoxidation Of Alkenesmentioning

confidence: 99%

Some Synthetic Uses of Double‐Bonded Functional Groups

Hoyle

2009

Patai's Chemistry of Functional Groups

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A Novel Method for the Preparation of Acid-Sensitive Epoxides from Olefins with the Combined Use of Molecular Oxygen and Aldoacetal Catalyzed by a Cobalt(II) Complex

Cited by 28 publications

References 21 publications

Syntheses and Stuctures of Alkyl Peroxo Adducts of β-Diketonate Cobalt(III) Complexes and Their Role in Oxidation of Hydrocarbons and Olefin Epoxidation

Syntheses and Stuctures of Alkyl Peroxo Adducts of β-Diketonate Cobalt(III) Complexes and Their Role in Oxidation of Hydrocarbons and Olefin Epoxidation

Selective Oxidation of Vinyl Ethers and Silyl Enol Ethers with Hydrogen Peroxide Catalyzed by Peroxotungstophosphate

Some Synthetic Uses of Double‐Bonded Functional Groups

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