Enantiopure <i>C</i><sub>1</sub>-Symmetric Bis(imino)pyridine Cobalt Complexes for Asymmetric Alkene Hydrogenation

Monfette, Sébastien; Turner, Zoë R.; Semproni, Scott P.; Chirik, Paul J.

doi:10.1021/ja300503k

Cited by 313 publications

(202 citation statements)

References 36 publications

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“…Enantiopure versions of these type of complexes have been structurally characterised and shown to be active catalysts for asymmetric alkene hydrogenation. 85 The same type of complexes have been used for alkene hydroboration with pinacolborane (HBPin). 86 The bis(imidazolidene)pyridine methyl complex, [(CNC)Co(II)Me] + , structurally related to the above (bis)iminopyridine, was also obtained by oxidation of [(CNC)CoMe] with ferrocenium.…”

Section: Groupmentioning

confidence: 99%

Methyl Complexes of the Transition Metals

Campos

López‐Serrano

Peloso

et al. 2016

Chemistry A European J

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Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, i.e. based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last 5 years. After a panoramic overview on M-CH3 compounds of groups 3 to 11 which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.

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Section: Groupmentioning

confidence: 99%

Methyl Complexes of the Transition Metals

Campos

López‐Serrano

Peloso

et al. 2016

Chemistry A European J

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“…[ 8 , 9 ] Chirik's chiral bis-imino-pyridine cobalt complexes gave promising enantiomeric excesses in the hydrogenation of styrene-derived terminal alkenes. [8] Milstein has reported pincerbased iron hydrogenation catalysts for symmetric reduction of ketones. [10,11 ] Morris and co-workers have applied chiral ironbased hydrogenation catalysts with tridentate [Fe(P-N-P)] and tetradentate [Fe(P−N−N−P) ligands in the asymmetric hydrogenation of ketones and imines.…”

Section: Introductionmentioning

confidence: 99%

Iron/Brønsted Acid Catalyzed Asymmetric Hydrogenation: Mechanism and Selectivity‐Determining Interactions

Hopmann

2015

Chemistry A European J

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Hydrogenation catalysts involving abundant base metals such as cobalt or iron are promising alternatives to precious metal systems. Despite rapid progress in this field, base metal catalysts do not yet achieve the activity and selectivity levels of their precious metal counterparts. Rational improvement of base metal complexes is facilitated by detailed knowledge about their mechanisms and selectivity-determining factors. The mechanism for asymmetric imine hydrogenation with Knölker's iron complex in presence of a chiral phosphoric acid is here investigated computationally at the DFT-D level of theory, with models of up to 160 atoms. The resting state of the system is found to be an adduct between the iron complex and the deprotonated acid. Rate-limiting H2 splitting is followed by a step-wise hydrogenation mechanism, where the phosphoric acid acts as the proton donor. C-H…O interactions between the phosphoric acid and the substrate are involved in the stereocontrol at the final hydride transfer step. Computed enantiomeric ratios show excellent agreement with experiment, indicating that DFT-D is able to correctly capture the selectivitydetermining interactions of this system.

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“…Precatalyst 2 was effective for the borylation of furans and N-methyl indole, although in some cases competing substrate reduction was observed, consistent with the known hydrogenation activity of this class of cobalt alkyl. 29,30 With 3, exclusive borylation of the position adjacent to the heteroatom was observed with each substrate correlating with the relative acidity of the C−H bonds. 4,31 For parent furan and thiophene, the borylation of the initial product was sufficiently rapid that the 2,5-disubstituted product was also observed.…”

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confidence: 99%

Cobalt-Catalyzed C–H Borylation

2014

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A family of pincer-ligated cobalt complexes has been synthesized and are active for the catalytic C-H borylation of heterocycles and arenes. The cobalt catalysts operate with high activity and under mild conditions and do not require excess borane reagents. Up to 5000 turnovers for methyl furan-2-carboxylate have been observed at ambient temperature with 0.02 mol % catalyst loadings. A catalytic cycle that relies on a cobalt(I)-(III) redox couple is proposed.

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Enantiopure C₁-Symmetric Bis(imino)pyridine Cobalt Complexes for Asymmetric Alkene Hydrogenation

Abstract: Enantiopure C(1)-symmetric bis(imino)pyridine cobalt chloride, methyl, hydride, and cyclometalated complexes have been synthesized and characterized. These complexes are active as catalysts for the enantioselective hydrogenation of geminal-disubstituted olefins.

Cited by 313 publications

References 36 publications

Methyl Complexes of the Transition Metals

Methyl Complexes of the Transition Metals

Iron/Brønsted Acid Catalyzed Asymmetric Hydrogenation: Mechanism and Selectivity‐Determining Interactions

Cobalt-Catalyzed C–H Borylation

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Enantiopure C1-Symmetric Bis(imino)pyridine Cobalt Complexes for Asymmetric Alkene Hydrogenation

Abstract: Enantiopure C(1)-symmetric bis(imino)pyridine cobalt chloride, methyl, hydride, and cyclometalated complexes have been synthesized and characterized. These complexes are active as catalysts for the enantioselective hydrogenation of geminal-disubstituted olefins.

Cited by 313 publications

References 36 publications

Methyl Complexes of the Transition Metals

Methyl Complexes of the Transition Metals

Iron/Brønsted Acid Catalyzed Asymmetric Hydrogenation: Mechanism and Selectivity‐Determining Interactions

Cobalt-Catalyzed C–H Borylation

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Resources

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Enantiopure C₁-Symmetric Bis(imino)pyridine Cobalt Complexes for Asymmetric Alkene Hydrogenation