Steric effects in the tetracyanoethylene catalysed methanolysis of some cyclohexane epoxides

Uyanık, Cavit; Hanson, James R.; Hitchcock, Peter B.; Lazar, Meredith A.

doi:10.1016/j.tet.2005.01.030

Cited by 5 publications

(3 citation statements)

References 8 publications

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“…Soluble compounds or complexes of main group metals, transition metals, and lanthanides are well‐known for their Lewis acidity and have been investigated specifically for their ability to catalyze the alcoholysis of epoxides. The catalytic activities of non‐metallic Lewis acids like BF 3 , CBr 4 , hydrazine sulphate, molecular iodine, iminium triflate, and trimethylsilyl triflate, as well as compounds able to participate in single‐electron reactions like 2,3‐dichloro‐5,6‐dicyano‐p‐benzoquinone, tetracyanoethylene, ceric ammonium nitrate, N ‐methylpyrrolidine‐2‐one hydrotribromide, and 1‐benzyl‐2,4,6‐triphenylpyridinium tetrafluoroborate, have also been explored. Many of these compounds are labeled as “mild” and “highly‐efficient” catalysts that are capable of rendering desired products in excellent yields (>90%) at room temperature within minutes to a few hours, but a close examination of the literature reveals that these claims often only hold true when the nucleophiles are short‐chain primary alcohols (usually methanol) and are used in large excess (10–100 eq.…”

Section: Introductionmentioning

confidence: 99%

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

McLeod

Tsarevsky

2015

J. Polym. Sci. Part A: Polym. Chem.

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Polymers containing electrophilic moieties, such as activated esters, epoxides, and alkyl halides, can be readily modified with a variety of nucleophiles to produce useful functional materials. The modification of epoxide-containing polymers with amines and other strong nucleophiles is welldocumented, but there are no reports on the modification of such polymers with alcohols. Using phenyloxirane and glycidyl butyrate as low molecular weight model compounds, it was determined that the acid-catalyzed ring-opening of arylsubstituted epoxides by alcohols to form b-hydroxy ether products was significantly more efficient than that of alkylsubstituted epoxides. An aryl epoxide-type styrenic monomer, 4-vinylphenyloxirane (4VPO), was synthesized in high yield using an improved procedure and then polymerized in a controlled manner under reversible addition-fragmentation chaintransfer (RAFT) polymerization conditions. A successful chain extension with styrene proved the high degree of chain-end functionalization of the poly4VPO-based macro chain transfer agent. Poly4VPO was modified with a library of alcohols and phenols, some of which contained reactive functionalities, e.g., azide, alkyne, allyl, etc., using either CBr 4 (in PhCN at 90 8C for 2-3 days) or BF 3 (in CH 2 Cl 2 at ambient temperature over 30 min) as the catalyst. The resulting b-hydroxy ether-functionalized homopolymers were characterized using size exclusion chromatography, 1 H NMR and IR spectroscopy, and thermal gravimetric analysis.

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Section: Introductionmentioning

confidence: 99%

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

McLeod

Tsarevsky

2015

J. Polym. Sci. Part A: Polym. Chem.

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“…α-Pinene epoxide 1 in methanol gave 8-methoxy-p-menth-6-en-2αol (trans-sobrerol 8-methyl ether) 3 (200 mg, 33%) as a colourless oil. 4 Under similar conditions, α-pinene epoxide 1 in ethanol gave 8-ethoxy-p-menth-6-en-2α-ol 4 (342 mg, 53%) as a colourless oil.…”

Section: Reaction Of Epoxides With Tetracyanoethylenementioning

confidence: 92%

“…The structures of the products indicate that when TCNE is used as a mild π-acid catalyst for the cleavage of hydroxyepoxides, the hydroxyl group can participate in the reaction. 4 The hydrolysis of the epoxides of αand β-pinene has been studied previously under a wide variety of conditions. 5,6 The epoxide of α-pinene afforded products arising from skeletal rearrangement and C-C bond cleavage.…”

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confidence: 99%

The Formation of Sobrelol Ethers by the Alcoholysis of Pinene Epoxides

Erdagi

Boztas

Uyanık

2016

Journal of Chemical Research

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Tetracyanoethylene (TCNE) is a mild π-acid catalyst which has proved to be of value in the cleavage of epoxides. 1 It has been used for the methanolysis of steroidal epoxides which followed a normal epoxide hydrolysis pathway in which there was a transanti-periplanar relationship between, the resultant methoxy and hydroxy groups. 2,3 In these cases, the reaction proceeded without the skeletal rearrangement that has been found in other conditions. The regiochemistry and stereochemistry of the TCNE catalysed methanolysis of some cyclohexane epoxides have been directed by the presence of an additional hydroxyl group. The structures of the products indicate that when TCNE is used as a mild π-acid catalyst for the cleavage of hydroxyepoxides, the hydroxyl group can participate in the reaction. 4 The hydrolysis of the epoxides of αand β-pinene has been studied previously under a wide variety of conditions. 5,6 The epoxide of α-pinene afforded products arising from skeletal rearrangement and C-C bond cleavage. Under very mild aqueous conditions trans-sobrelol was the major product and its formation has recently been thoroughly investigated. 7 Under various conditions, 5,6 the epoxide of β-pinene gave myrtenal which retains the pinane skeleton and only formed C-C cleavage products such as perillyl alcohol (please see footnote in Buchi and coworkers). 8 Sobrelol has attracted clinical interest and it has been used 9-11 as a mucolytic agent in the treatment of chronic bronchial inflammatory disease.In our previous work, 4 we showed that methanolysis of the epoxide (1) of α-pinene catalysed by TCNE gave the 8-monomethyl ether (3) of trans-sobrelol. In this paper, we describe the formation of the 8-alkoxy ethers of trans-sobrelol and its 7-hydroxy relative by the TCNE catalysed alcoholysis of the epoxides of αand β-pinene in methanol, ethanol, 2-propanol and 1-butanol.Ethanolysis of the epoxide of α-pinene epoxide (1), catalysed by TCNE in ethanol gave 8-ethoxy-p-menth-6-en-2α-ol (4). The peaks at 3320 cm -1 and 1640 cm -1 in the FTIR spectra of 4 revealed the presence of a hydroxyl group and a double bond respectively. The 1 H NMR spectrum contained the signals of ethoxy protons (OCH 2 CH 3 ) resonance (δ H = 3.34 ppm) as a quartet (J = 5.9 Hz) whilst the (OCH 2 CH 3 ) resonance (δ H = 1.72) was a triplet (J = 5.9 Hz). The signals at 5.5 ppm and 3.94 ppm were assigned to the protons attached to the double bond and the hydroxyl group, respectively. In addition, there was a six-proton singlet at δ 1.12 assigned to the gem-dimethyl group (H-9 and H-10) and a three-proton singlet at δ 1.77 assigned to the methyl group (H-7) attached to the double bond.Treatment of the epoxide of α-pinene oxide (1) with TCNE in isopropanol gave 8-isopropoxy-p-menth-6-en-2α-ol (5). The 1 H NMR spectrum of 5 established the presence of a OCH(CH 3 ) 2 group [δ H 1.14 (6H, d,

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methanolysis

Noir¹

2020

Catalysis From a to Z

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Steric effects in the tetracyanoethylene catalysed methanolysis of some cyclohexane epoxides

Cited by 5 publications

References 8 publications

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

Well-defined epoxide-containing styrenic polymers and their functionalization with alcohols

The Formation of Sobrelol Ethers by the Alcoholysis of Pinene Epoxides

methanolysis

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