Evaluation of enantiopure and non-enantiopure Co(III)-salen catalysts and their counter-ion effects in the hydrolytic kinetic resolution (HKR) of racemic epichlorohydrin

Key, Rebecca E.; Venkatasubbaiah, Krishnan; Jones, Christopher W.

doi:10.1016/j.molcata.2012.08.013

Cited by 15 publications

(4 citation statements)

References 34 publications

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“…Co(III)Salen and Co(III)Porphyrin based catalysts are effective catalysts for the ringopening of epoxides with water, [12] alcohols, [18,19,44] and other nucleophiles. [45,46] While our past work demonstrated that ring-opening with alcohols can be achieved with very high regioselectivity, [19] recent studies identified counter-anion loss and/or reduction from Co(III) to Co(II) as key causes of catalyst deactivation.…”

Section: Resultsmentioning

confidence: 99%

Co(III) complexes of tetradentate X3L type ligands: Synthesis, electronic structure, and reactivity

Feng

Burns

Lee

et al. 2015

Inorganica Chimica Acta

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Co(III) complexes of DPP (DPP = (Z)-2-(2-((5-(2-hydroxyphenyl)-1H-pyrrol-2yl)(phenyl)methylene)-2H-pyrrol-5-yl)phenol) and two fluorinated DPP variants are prepared, structurally characterized, and their reactivity explored in the catalytic ringopening of 1,2-epoxyhexane with alcohols. While the related Co(III) salen and porphyrin complexes are highly active for this catalytic transformation, the Co(III) DPP complexes are shown to be catalytically inert under the conditions studied. Computational characterization of the electronic structure of all the complexes shows that the Co(III)complexes ligated by the DPP ligands (tetradentate X 3 L type) do not have sufficient Lewis acidity to activate the epoxide, whereas the Co(III) porphyrin and salen (tetradentate X 2 L 2 type) incorporate a counter-ion that draws electron density away from the metal center, creating a more Lewis acidic Co species that is catalytically active for

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Section: Resultsmentioning

confidence: 99%

Co(III) complexes of tetradentate X3L type ligands: Synthesis, electronic structure, and reactivity

Feng

Burns

Lee

et al. 2015

Inorganica Chimica Acta

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“…On the other hand, HA4 and HB4 showed TOF values ranging from 10 to 16, which were about one-fifth of other systems (Table 5) [21,40]. However, HA4 showed an excellent selectivity factor in fresh cycle (fresh of HA4, Table 5), which was comparable to the polymer-supported Co-salen complexes [21].…”

Section: Catalyst Stability and Catalytic Cyclementioning

confidence: 90%

“…However, e.e. of diol was controlled by nucleophilic attack of activated salen-Co(III)-OH, which might be depressed by Br -stemmed from n-Bu 4 NBr [40].…”

Section: Optimization Of Catalytic Conditionsmentioning

confidence: 99%

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Macroporous Helical Silica Immobilizing Cobalt-Salen Complex Catalyzed Asymmetric Hydrolytic Kinetic Resolution of Epoxides

Huang

Liu

et al. 2015

Catal Surv Asia

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Based on an entropy-driven principle, new macroporous helical silica rods were synthesized by using mild templates in sol-gel, then functionalized for immobilizing Co-salen complexes to catalyze enantioselective hydrolytic kinetic resolution of epoxides. Characterization revealed both silica supports and heterogeneous Co-salen complexes were macroporous helical materials with affirmative chirality. Catalysis revealed enantioselective adsorption of substrate on silica supports dominated major configuration of resolution products rather than configuration of Co-salen. The (S)-amino alcohol-doped silica and Co-(R,R)salen comprised the most enantioselective combination, which proved chiral synergy between support and Co-salen did exist. This work would contribute to the design of new support materials for asymmetric catalysis.

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Enantioselective Cobalt‐Catalysed Transformations

Pellissier

2019

Cobalt Catalysis in Organic Synthesis

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Evaluation of enantiopure and non-enantiopure Co(III)-salen catalysts and their counter-ion effects in the hydrolytic kinetic resolution (HKR) of racemic epichlorohydrin

Cited by 15 publications

References 34 publications

Co(III) complexes of tetradentate X3L type ligands: Synthesis, electronic structure, and reactivity

Co(III) complexes of tetradentate X3L type ligands: Synthesis, electronic structure, and reactivity

Macroporous Helical Silica Immobilizing Cobalt-Salen Complex Catalyzed Asymmetric Hydrolytic Kinetic Resolution of Epoxides

Enantioselective Cobalt‐Catalysed Transformations

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