Effector responsive hydroformylation catalysis

Bai, Shao‐Tao; Sinha, Vivek; Kluwer, Alexander M.; Linnebank, Pim R.; Abiri, Zohar; Dydio, Paweł; Lutz, Martin; Bruin, Bas de; Reek, Joost N. H.

doi:10.1039/c9sc02558h

Cited by 18 publications

(10 citation statements)

References 103 publications

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“…The 18-electron Rh–H species 1 is considered as the reference point for the computed energies. Several in situ spectroscopic studies have in fact detected 1 and have assigned a trigonal bipyramidal geometry as well . The geometric features of 1 would have implications in the geometries of other 18-electron intermediates ( 3 , 5 , and 7 ) and more so on the critical transition states ( TS1 and TS2 ), as shown in Scheme .…”

Section: Results and Discussionmentioning

confidence: 96%

Unraveling the Importance of Noncovalent Interactions in Asymmetric Hydroformylation Reactions

2020

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For catalytic asymmetric hydroformylation (AHF) of alkenes to chiral aldehydes, though a topic of high interest, the contemporary developments remain largely empirical owing to rather limited molecular insights on the origin of enantioselectivity. Given this gap, herein, we present the mechanistic details of Rh-(S,S)-YanPhoscatalyzed AHF of α-methylstyrene, as obtained through a comprehensive DFT (ω-B97XD and M06) study. The challenges with the double axially chiral YanPhos, bearing an N-benzyl BINOL-phosphoramidite and a BINAP-bis(3,5-t-Bu-aryl)phosphine, are addressed through exhaustive conformational sampling. The C−H•••π, π•••π, and lone pair•••π noncovalent interactions (NCIs) between the N-benzyl and the rest of the chiral ligand limit the N-benzyl conformers. Similarly, the C−H•••π and π•••π NCIs between the chiral catalyst and α-methylstyrene render the siface binding to the Rh-center more preferred over the re-face. The transition state (TS) for the regiocontrolling migratory insertion, triggered by the Rh-hydride addition to the alkene, to the more substituted α-carbon is 3.6 kcal/mol lower than that to the β-carbon, thus favoring the linear chiral aldehyde over the achiral branched alternative. In the linear pathway, the TS for the hydride addition to the si-face is 1.5 kcal/mol lower than that to the re-face, with a predicted ee of 85% for the S aldehyde (expt. 87%). The energetic span analysis reveals the reductive elimination as the turnover determining step for the preferred S linear aldehyde. These molecular insights could become valuable for exploiting AHF reactions for substituted alkenes and for eventual industrial implementation.

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Section: Results and Discussionmentioning

confidence: 96%

Unraveling the Importance of Noncovalent Interactions in Asymmetric Hydroformylation Reactions

2020

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“…Typically, additives interact with the supporting ligand (or two supporting ligands interact with each other) to change the overall steric profile or the ligand bite angle, without altering the coordination number. This strategy has been highly effective in tuning the linear/branched regioselectivity in alkene hydroformylation, , including examples of cation–crown interactions tuning ligand bite angle. ,, Because the macrocycle in pincer-crown ether ligands is directly bound to the catalyst, cation binding influences the primary coordination sphere, which we propose to be essential for controlling regioselectivity and stereoselectivity between two sterically similar internal olefin isomers.…”

Section: Discussionmentioning

confidence: 99%

“…An alternative approach uses a single metal/ligand combination in conjunction with external additives to control the selectivity (Figure B). − Noncovalent modification has been particularly impactful in the field of alkene hydroformylation, with additives (including alkali metal cations) − interacting with the catalyst to tune the aldehyde product regioselectivity between terminal or secondary positions . Finding a single catalyst that can access two states capable of a dramatic switch in regioselectivity remains a challenge in hydroformylation. , The challenge seems even more daunting for olefin isomerization, where two states must discriminate between sterically similar internal olefins. We are not aware of any examples of olefin isomerization catalysts with additive-responsive selectivity.…”

Section: Introductionmentioning

confidence: 99%

Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst

et al. 2021

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The catalytic transposition of double bonds holds promise as an ideal route to alkenes with value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst is developed for the selective production of either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on non-covalent modifications. File list (9) download file view on ChemRxiv Camp_SwitchableRegioselectivity_Manuscript_ChemRxiv... (2.31 MiB) download file view on ChemRxiv Camp_SwitchableRegioselectivity_SI_ChemRxiv_Submis... (3.22 MiB) download file view on ChemRxiv 215c5b.cif (1.97 MiB) download file view on ChemRxiv 218c6a.cif (1.67 MiB) download file view on ChemRxiv 315c5b.cif (1.89 MiB) download file view on ChemRxiv 318c6a.cif (3.47 MiB) download file view on ChemRxiv 318c6b.cif (1.97 MiB) download file view on ChemRxiv Na118c6a.cif (1.31 MiB) download file view on ChemRxiv 218c6b.cif (3.23 MiB)

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“…Typically, additives interact with the supporting ligand (or two supporting ligands interact with each other) to change the overall steric profile or the ligand bite angle, without altering the coordination number. This strategy has been highly effective in tuning the linear/branched regioselectivity in alkene hydroformylation, 24,33 including examples of cationcrown interactions tuning ligand bite angle. 26,27,30 Because the macrocycle in pincer-crown ether is directly bound to the catalyst, cation binding influences the primary coordination sphere, which we propose to be essential for controlling regioselectivity and stereoselectivity between two sterically similar internal olefin isomers.…”

Section: Discussionmentioning

confidence: 99%

Selecting Double Bond Positions with a Single Cation- Responsive Iridium Olefin Isomerization Catalyst

Camp¹,

Kita²,

Blackburn³

et al. 2020

Preprint

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<div><div><div><p>The catalytic transposition of double bonds holds promise as an ideal route to alkenes with value as fragrances, commodity chemicals, and pharmaceuticals; yet, selective access to specific isomers is a challenge, requiring independent development of different catalysts for different products. In this work, a single cation-responsive iridium catalyst is developed for the selective production of either of two different internal alkene isomers. In the absence of salts, a single positional isomerization of 1-butene derivatives furnishes 2-alkenes with exceptional regioselectivity and stereoselectivity. The same catalyst, in the presence of Na+, mediates two positional isomerizations to produce 3-alkenes. The synthesis of new iridium pincer-crown ether catalysts based on an aza-18-crown-6 ether proved instrumental in achieving cation-controlled selectivity. Experimental and computational studies guided the development of a mechanistic model that explains the observed selectivity for various functionalized 1-butenes, providing insight into strategies for catalyst development based on non-covalent modifications.</p></div></div></div>

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Effector responsive hydroformylation catalysis

Abstract: A bidentate ligand with an integrated anion receptor forms dimeric rhodium complexes that become monomeric upon binding acetate guest, which is the basis for effector responsive hydroformylation catalysis.

Cited by 18 publications

References 103 publications

Unraveling the Importance of Noncovalent Interactions in Asymmetric Hydroformylation Reactions

Unraveling the Importance of Noncovalent Interactions in Asymmetric Hydroformylation Reactions

Selecting Double Bond Positions with a Single Cation-Responsive Iridium Olefin Isomerization Catalyst

Selecting Double Bond Positions with a Single Cation- Responsive Iridium Olefin Isomerization Catalyst

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