Metal‐Catalyzed Hydrophosphination

Novas, Bryan T.; Waterman, Rory

doi:10.1002/cctc.202200988

Cited by 41 publications

(25 citation statements)

References 210 publications

(255 reference statements)

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“…Organophosphines are integral molecules in catalysis, synthetic chemistry, materials science, and more. − Metal-catalyzed hydrophosphination, the addition of a P–H bond across an unsaturated substrate, is one of the most promising and atom-economical P–C bond-forming reactions. − Progress has been made in expanding the available catalysts, scope, and selectivity of hydrophosphination in recent years. − However, limitations remain that hamper the synthetic utility of hydrophosphination. , Among the most notable limitations with known catalysts is that they often require special preparation and/or complex ancillary ligands and that most precatalysts are not air- and water-stable (i.e., not convenient). Known catalysts also have limitations in reactivity, often stymied by unactivated or highly substituted substrates, especially in intermolecular reactions. , …”

Section: Introductionmentioning

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.

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Section: Introductionmentioning

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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“…These are improvements in reactivity with challenging substrates, but more work is needed. (14) Recognizing the potential enhancement of reactivity via photocatalysis using copper, a tri-substituted styrene was screened with copper. Treatment of 1-phenyl-1-cyclohexene with 2 equiv.…”

Section: Hydrophosphination Of Difficult Substratesmentioning

confidence: 99%

“…1,2,3 Metalcatalyzed hydrophosphination, the addition of a P-H bond across an unsaturated substrate, is one of the most promising, and atom-economical, P-C bond forming reactions. [4][5][6][7][8][9][10][11][12][13][14] Progress has been made in expanding the available catalysts, scope, and selectivity of hydrophosphination in recent years. However, limitations remain that hamper the synthetic utility of hydrophosphination.…”

Section: Introductionmentioning

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

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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 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.

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“…For example, there are only two prior reports of the hydrophosphination of βmethyl styrene with diphenylphosphine and each required temperatures of 100 °C with 41% the highest yield achieved by a cerium MOF after 5 days of heating. 18,40 Under 360 nm irradiation at ambient temperature, hydrophosphination of a neat mixture of cis/trans β-methyl styrene with diphenylphosphine in the presence of 5 mol % of CuOAc (14) proceeds to 73% conversion to product 13d in less than 3 d (Eq 10). Compound 1 achieves 25% conversion under the same conditions after 3 d, demonstrating how even simple prefabricated copper(I) can be valuable in saving the catalytic activation step in these longer reactions.…”

Section: Hydrophosphination Of Difficult Substratesmentioning

confidence: 99%

“…Experiments to rationalize the formation of the cis product, its variability in formation, and optimization to select for the trans-isomer and further exploration of both stereo-and enantioselectivity is ongoing. (14) (15)…”

Section: Hydrophosphination Of Difficult Substratesmentioning

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

Metal‐Catalyzed Hydrophosphination

Cited by 41 publications

References 210 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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