Stereospecific sp3 C–H oxidation with m-CPBA: A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative

Oksana V. Nesterova, Katerina V. Kasyanova, Valeriya G. Makhankova, Vladimir N. Kokozay, Olga Yu Vassilyeva, Brian W. Skelton, Dmytro S. Nesterov, Armando J.L. Pombeiro

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

The mono- and binuclear Schiff base complexes [CoL3]·DMF (1) and [CoCdL3Cl2]·0.5H2O (2) were facilely synthesized using zerovalent cobalt and cadmium chloride (for 2) as starting materials and the pre-formed pro-ligand HL (2-methoxy-6-[(methylimino)methyl]phenol, the product of condensation of o-vanillin and methylamine) in air. The compounds were characterized by single crystal X-ray diffraction analysis and spectroscopic methods in solution and in the solid state. Both complexes demonstrate a profound catalytic activity in the stereoselective oxidation of cis-1,2-dimethylcyclohexane (model substrate) with m-CPBA (m-chloroperbenzoic acid) under mild conditions in the presence of promoters of various acidity (HNO3, TFA and HOAc). The heterometallic binuclear CoIIICdII pre-catalyst (2) was more active than the mononuclear CoIII one (1), exhibiting higher products yields up to 51% and excellent stereospecificity (up to 99.2% retention of stereoconfiguration). This result could be associated with a synergistic effect of two different metals in 2. Based on the large obtained kinetic isotope effect and H218O labeling studies, the overall reaction mechanism was proposed to proceed without the participation of free alkyl radicals. The acidity of the promoter was shown to influence catalytic parameters for both 1 and 2 so that the better parameters are achieved with the acid possessing lower pKa values (a stronger acid). The comparison of the catalytic behaviours of 1 and 2 is discussed in detail considering relevant examples from the literature.

Original languageEnglish
Pages (from-to)171-184
Number of pages14
JournalApplied Catalysis A: General
Volume560
DOIs
Publication statusPublished - 25 Jun 2018

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Schiff Bases
Acidity
Derivatives
Cadmium Chloride
Oxidation
Catalysts
Acids
Free radicals
Cadmium chloride
Isotopes
Labeling
X ray diffraction analysis
Catalyst activity
Metals
Single crystals
Ligands
Phenols
Kinetics
Condensation
Cobalt

Cite this

Nesterova, Oksana V. ; Kasyanova, Katerina V. ; Makhankova, Valeriya G. ; Kokozay, Vladimir N. ; Vassilyeva, Olga Yu ; Skelton, Brian W. ; Nesterov, Dmytro S. ; Pombeiro, Armando J.L. / Stereospecific sp3 C–H oxidation with m-CPBA : A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative. In: Applied Catalysis A: General. 2018 ; Vol. 560. pp. 171-184.
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title = "Stereospecific sp3 C–H oxidation with m-CPBA: A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative",
abstract = "The mono- and binuclear Schiff base complexes [CoL3]·DMF (1) and [CoCdL3Cl2]·0.5H2O (2) were facilely synthesized using zerovalent cobalt and cadmium chloride (for 2) as starting materials and the pre-formed pro-ligand HL (2-methoxy-6-[(methylimino)methyl]phenol, the product of condensation of o-vanillin and methylamine) in air. The compounds were characterized by single crystal X-ray diffraction analysis and spectroscopic methods in solution and in the solid state. Both complexes demonstrate a profound catalytic activity in the stereoselective oxidation of cis-1,2-dimethylcyclohexane (model substrate) with m-CPBA (m-chloroperbenzoic acid) under mild conditions in the presence of promoters of various acidity (HNO3, TFA and HOAc). The heterometallic binuclear CoIIICdII pre-catalyst (2) was more active than the mononuclear CoIII one (1), exhibiting higher products yields up to 51{\%} and excellent stereospecificity (up to 99.2{\%} retention of stereoconfiguration). This result could be associated with a synergistic effect of two different metals in 2. Based on the large obtained kinetic isotope effect and H218O labeling studies, the overall reaction mechanism was proposed to proceed without the participation of free alkyl radicals. The acidity of the promoter was shown to influence catalytic parameters for both 1 and 2 so that the better parameters are achieved with the acid possessing lower pKa values (a stronger acid). The comparison of the catalytic behaviours of 1 and 2 is discussed in detail considering relevant examples from the literature.",
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author = "Nesterova, {Oksana V.} and Kasyanova, {Katerina V.} and Makhankova, {Valeriya G.} and Kokozay, {Vladimir N.} and Vassilyeva, {Olga Yu} and Skelton, {Brian W.} and Nesterov, {Dmytro S.} and Pombeiro, {Armando J.L.}",
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Stereospecific sp3 C–H oxidation with m-CPBA : A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative. / Nesterova, Oksana V.; Kasyanova, Katerina V.; Makhankova, Valeriya G.; Kokozay, Vladimir N.; Vassilyeva, Olga Yu; Skelton, Brian W.; Nesterov, Dmytro S.; Pombeiro, Armando J.L.

In: Applied Catalysis A: General, Vol. 560, 25.06.2018, p. 171-184.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Stereospecific sp3 C–H oxidation with m-CPBA

T2 - A CoIII Schiff base complex as pre-catalyst vs. its CoIIICdII heterometallic derivative

AU - Nesterova, Oksana V.

AU - Kasyanova, Katerina V.

AU - Makhankova, Valeriya G.

AU - Kokozay, Vladimir N.

AU - Vassilyeva, Olga Yu

AU - Skelton, Brian W.

AU - Nesterov, Dmytro S.

AU - Pombeiro, Armando J.L.

PY - 2018/6/25

Y1 - 2018/6/25

N2 - The mono- and binuclear Schiff base complexes [CoL3]·DMF (1) and [CoCdL3Cl2]·0.5H2O (2) were facilely synthesized using zerovalent cobalt and cadmium chloride (for 2) as starting materials and the pre-formed pro-ligand HL (2-methoxy-6-[(methylimino)methyl]phenol, the product of condensation of o-vanillin and methylamine) in air. The compounds were characterized by single crystal X-ray diffraction analysis and spectroscopic methods in solution and in the solid state. Both complexes demonstrate a profound catalytic activity in the stereoselective oxidation of cis-1,2-dimethylcyclohexane (model substrate) with m-CPBA (m-chloroperbenzoic acid) under mild conditions in the presence of promoters of various acidity (HNO3, TFA and HOAc). The heterometallic binuclear CoIIICdII pre-catalyst (2) was more active than the mononuclear CoIII one (1), exhibiting higher products yields up to 51% and excellent stereospecificity (up to 99.2% retention of stereoconfiguration). This result could be associated with a synergistic effect of two different metals in 2. Based on the large obtained kinetic isotope effect and H218O labeling studies, the overall reaction mechanism was proposed to proceed without the participation of free alkyl radicals. The acidity of the promoter was shown to influence catalytic parameters for both 1 and 2 so that the better parameters are achieved with the acid possessing lower pKa values (a stronger acid). The comparison of the catalytic behaviours of 1 and 2 is discussed in detail considering relevant examples from the literature.

AB - The mono- and binuclear Schiff base complexes [CoL3]·DMF (1) and [CoCdL3Cl2]·0.5H2O (2) were facilely synthesized using zerovalent cobalt and cadmium chloride (for 2) as starting materials and the pre-formed pro-ligand HL (2-methoxy-6-[(methylimino)methyl]phenol, the product of condensation of o-vanillin and methylamine) in air. The compounds were characterized by single crystal X-ray diffraction analysis and spectroscopic methods in solution and in the solid state. Both complexes demonstrate a profound catalytic activity in the stereoselective oxidation of cis-1,2-dimethylcyclohexane (model substrate) with m-CPBA (m-chloroperbenzoic acid) under mild conditions in the presence of promoters of various acidity (HNO3, TFA and HOAc). The heterometallic binuclear CoIIICdII pre-catalyst (2) was more active than the mononuclear CoIII one (1), exhibiting higher products yields up to 51% and excellent stereospecificity (up to 99.2% retention of stereoconfiguration). This result could be associated with a synergistic effect of two different metals in 2. Based on the large obtained kinetic isotope effect and H218O labeling studies, the overall reaction mechanism was proposed to proceed without the participation of free alkyl radicals. The acidity of the promoter was shown to influence catalytic parameters for both 1 and 2 so that the better parameters are achieved with the acid possessing lower pKa values (a stronger acid). The comparison of the catalytic behaviours of 1 and 2 is discussed in detail considering relevant examples from the literature.

KW - O isotopic labeling

KW - Homogeneous catalysis

KW - m-Chloroperbenzoic acid

KW - Metal complex catalysis

KW - Stereoselective C–H oxidation

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U2 - 10.1016/j.apcata.2018.05.004

DO - 10.1016/j.apcata.2018.05.004

M3 - Article

VL - 560

SP - 171

EP - 184

JO - APPLIED CATALYSIS A-GENERAL

JF - APPLIED CATALYSIS A-GENERAL

SN - 0926-860X

ER -