Effect of Photolysis on Zirconium Amino Phenoxides for the Hydrophosphination of Alkenes: Improving Catalysis

Novas, Bryan T.; Morris, Jacob A.; Liptak, Matthew D.; Waterman, Rory

doi:10.3390/photochem2010007

Cited by 5 publications

(8 citation statements)

References 46 publications

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“…Nevertheless, computational data give a strong preliminary indication that photoexcitation for copper may facilitate insertion via weakening of the Cu−P bond, as has now been seen for several zirconium compounds. 66,67 Most germane to catalysis, it suggests that this photoactivity is substrateindependent and new challenging substrates can be realized via photocatalytic hydrophosphination using copper.…”

Section: Proposed Catalytic Cyclementioning

confidence: 99%

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding That Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

et al. 2022

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Readily available and bench-stable Cu(acac) 2 (1) addresses many challenges in exploratory hydrophosphination catalysis. Mechanistic investigations were performed to answer questions that remain about the reactivity of 1, the role of light in catalysis, and to provide direction for further study. A divergent Hammett plot indicates different mechanisms based on electron density at the alkene substrate. A radical process was eliminated based on trapping reactions and in situ electron paramagnetic resonance experiments. Isotopic labeling experiments, a zwitterionic trapping experiment, stoichiometric model reactions, and catalytic reactions using proxy intermediates indicate that both the conjugate addition and insertion-based mechanistic pathways occur with this system, depending on the unsaturated substrate. Computational analysis indicates that the lowest energy transition is a ligand-to-metal charge transfer from the phosphido ligand where the LUMO has significant Cu−P antibonding character, suggesting that a weakened Cu−P bond accelerates insertion under photocatalytic conditions. This hypothesis explains the greater activity of 1 compared to prior copper-catalyzed hydrophosphination reports and appears to be a general phenomenon for copper(I) catalysts. These results have been leveraged to achieve heretofore unknown catalytic hydrophosphination reactivity, namely the diastereoselective hydrophosphination of a tri-substituted styrene substrate.

show abstract

Section: Proposed Catalytic Cyclementioning

confidence: 99%

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding That Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…In particular, photocatalytic hydrophosphination with zirconium appears to depend on a P n → Zr d LMCT that results in the lengthening of the Zr-P bond to promote facile substrate insertion. 61,62 This seemingly benign transition results in bond elongation due to significant Zr-P antibonding character of the acceptor orbital. To probe for a potentially related phenomenon with copper, compound 9 was explored by spectroscopic and computational analyses.…”

Section: Computational Analysis/role Of Lightmentioning

confidence: 99%

“…Nevertheless, computational data gives a strong preliminary indication that photoexcitation for copper may facilitate insertion via weakening of the Cu-P bond, as has now been seen for several zirconium compounds. 61,62 Most germane to catalysis, it suggests that this photoactivity is substrate independent and new, challenging substrates can be realized via photocatalytic hydrophosphination using copper.…”

Section: Computational Analysis/role Of Lightmentioning

confidence: 99%

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding that Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

Dannenberg

Seth

Finfer

et al. 2022

Preprint

View full text Add to dashboard Cite

Readily available and bench-stable Cu(acac)2 (1) addresses many challenges in exploratory hydrophosphination catalysis. Mechanistic investigations were performed to answer questions that remain about the reactivity of 1, the role of light in the catalysis, and to provide direction for further study. A divergent Hammett plot indicates differing mechanisms based on electron density at the alkene substrate. A radical process was eliminated based on trapping reactions and in-situ EPR experiments. Isotopic labeling experiments, a zwitterionic trapping experiment, stoichiometric model reactions, and catalytic reactions using proxy intermediates indicate that both conjugate addition and insertion-based mechanistic pathways occur with this system, depending on the unsaturated substrate. Computational analysis indicates that the lowest energy transition is a ligand-to-metal charge transfer (LMCT) from the phosphido ligand where the LUMO has significant Cu–P antibonding character, suggesting that a weakened Cu–P bond accelerates insertion under photocatalytic conditions. This hypothesis explains the greater activity of 1 compared to copper-catalyzed hydrophosphination reports and appears to be a general phenomenon for copper(I) catalysts. These results have been leveraged to achieve heretofore unknown catalytic hydrophosphination reactivity, namely the diastereoselective hydrophosphination of a tri-substituted styrene substrate.

show abstract

“…In particular, photocatalytic hydrophosphination with zirconium appears to depend on a P n → Zr d LMCT that results in the lengthening of the Zr-P bond to promote facile substrate insertion. 66,67 This seemingly benign transition results in bond elongation due to significant Zr-P antibonding character of the acceptor orbital. To probe for a potentially related phenomenon with copper, compound 9 was explored by spectroscopic and computational analyses.…”

Section: Computational Analysis/role Of Lightmentioning

confidence: 99%

“…Nevertheless, computational data gives a strong preliminary indication that photoexcitation for copper may facilitate insertion via weakening of the Cu-P bond, as has now been seen for several zirconium compounds. 66,67 Most germane to catalysis, it suggests that this photoactivity is substrate independent and new, challenging substrates can be realized via photocatalytic hydrophosphination using copper.…”

Section: Computational Analysis/role Of Lightmentioning

confidence: 99%

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding that Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

Dannenberg

Seth

Finfer

et al. 2022

Preprint

View full text Add to dashboard Cite

Readily available and bench-stable Cu(acac)2 (1) addresses many challenges in exploratory hydrophosphination catalysis. Mechanistic investigations were performed to answer questions that remain about the reactivity of 1, the role of light in the catalysis, and to provide direction for further study. A divergent Hammett plot indicates differing mechanisms based on electron density at the alkene substrate. A radical process was eliminated based on trapping reactions and in-situ EPR experiments. Isotopic labeling experiments, a zwitterionic trapping experiment, stoichiometric model reactions, and catalytic reactions using proxy intermediates indicate that both conjugate addition and insertion-based mechanistic pathways occur with this system, depending on the unsaturated substrate. Computational analysis indicates that the lowest energy transition is a ligand-to-metal charge transfer (LMCT) from the phosphido ligand where the LUMO has significant Cu–P antibonding character, suggesting that a weakened Cu–P bond accelerates insertion under photocatalytic conditions. This hypothesis explains the greater activity of 1 compared to copper-catalyzed hydrophosphination reports and appears to be a general phenomenon for copper(I) catalysts. These results have been leveraged to achieve heretofore unknown catalytic hydrophosphination reactivity, namely the diastereoselective hydrophosphination of a tri-substituted styrene substrate.

show abstract

Effect of Photolysis on Zirconium Amino Phenoxides for the Hydrophosphination of Alkenes: Improving Catalysis

Cited by 5 publications

References 46 publications

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding That Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding That Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding that Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

Divergent Mechanistic Pathways for Copper(I) Hydrophosphination Catalysis: Understanding that Allows for Diastereoselective Hydrophosphination of a Tri-substituted Styrene

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