Isodesmic Reactions in Catalysis – Only the Beginning?

Bhawal, Benjamin N.; Morandi, Bill

doi:10.1002/ijch.201700116

Cited by 26 publications

(14 citation statements)

References 68 publications

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“…Out of the several catalytic transformations that are commonly used, isodesmic reactions have attractive features. In these chemical transformations, the type of chemical bond cleaved in the reactant is the same as the bond formed in the product . Notable examples of such a process include transfer hydrogenation and olefin metathesis (Scheme ).…”

mentioning

confidence: 99%

Isodesmic C–H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis

et al. 2019

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The potential advantages of using arylboronic esters as boron sources in C−H borylation are discussed. The concept is showcased using commercially available 2-mercaptopyridine as a metal-free catalyst for the transfer borylation of heteroarenes using arylboronates as borylation agents. The catalysis shows a unique functional group tolerance among C− H borylation reactions, tolerating notably terminal alkene and alkyne functional groups. The mechanistic investigation is also described.

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confidence: 99%

Isodesmic C–H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis

et al. 2019

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“…54 We imagined that a Rh catalyst could work in tandem with a sacrificial strained olefin acceptor to transfer a hydrogen atom and formyl group from the aldehyde substrate. We postulated that the release of substantial ring strain in the olefin acceptor could offer a driving force for the isodesmic reaction 55 and allow for selective access to the desired olefin product. Notably, this process would avoid the intermediacy of CO gas, which could potentially act as a catalyst poison.…”

Section: Transfer Hydroformylationmentioning

confidence: 99%

Teaching Aldehydes New Tricks Using Rhodium- and Cobalt-Hydride Catalysis

2021

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Conspectus By using transition metal catalysts, chemists have altered the “logic of chemical synthesis” by enabling the functionalization of carbon–hydrogen bonds, which have traditionally been considered inert. Within this framework, our laboratory has been fascinated by the potential for aldehyde C–H bond activation. Our approach focused on generating acyl-metal-hydrides by oxidative addition of the formyl C–H bond, which is an elementary step first validated by Tsuji in 1965. In this Account, we review our efforts to overcome limitations in hydroacylation. Initial studies resulted in new variants of hydroacylation and ultimately spurred the development of related transformations (e.g., carboacylation, cycloisomerization, and transfer hydroformylation). Sakai and co-workers demonstrated the first hydroacylation of olefins when they reported that 4-pentenals cyclized to cyclopentanones, using stoichiometric amounts of Wilkinson’s catalyst. This discovery sparked significant interest in hydroacylation, especially for the enantioselective and catalytic construction of cyclopentanones. Our research focused on expanding the asymmetric variants to access medium-sized rings (e.g., seven- and eight-membered rings). In addition, we achieved selective intermolecular couplings by incorporating directing groups onto the olefin partner. Along the way, we identified Rh and Co catalysts that transform dienyl aldehydes into a variety of unique carbocycles, such as cyclopentanones, bicyclic ketones, cyclohexenyl aldehydes, and cyclobutanones. Building on the insights gained from olefin hydroacylation, we demonstrated the first highly enantioselective hydroacylation of carbonyls. For example, we demonstrated that ketoaldehydes can cyclize to form lactones with high regio- and enantioselectivity. Following these reports, we reported the first intermolecular example that occurs with high stereocontrol. Ketoamides undergo intermolecular carbonyl hydroacylation to furnish α-acyloxyamides that contain a depsipeptide linkage. Finally, we describe how the key acyl-metal-hydride species can be diverted to achieve a C–C bond-cleaving process. Transfer hydroformylation enables the preparation of olefins from aldehydes by a dehomologation mechanism. Release of ring strain in the olefin acceptor offers a driving force for the isodesmic transfer of CO and H2. Mechanistic studies suggest that the counterion serves as a proton-shuttle to enable transfer hydroformylation. Collectively, our studies showcase how transition metal catalysis can transform a common functional group, in this case aldehydes, into structurally distinct motifs. Fine-tuning the coordination sphere of an acyl-metal-hydride species can promote C–C and C–O bond-forming reactions, as well as C–C bond-cleaving processes.

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“…Furthermore, by avoiding the presence of B-H moieties throughout the catalytic transformation, it prevents sidereactions such as the hydroboration of unsaturated substrates. [72] The best borylation agent was found to be 2-furylBcat (53), although p-anisyl-(55) and p-tolylBcat (56) could also be used as stoichiometric boron sources.…”

Section: Catalytic Borylation By Selfassembled Lpsmentioning

confidence: 99%

Boron Lewis Pair Mediated C–H Activation and Borylation

Fontaine¹,

Desrosiers²

2021

Synthesis

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In the past years, the chemistry of Frustrated Lewis pairs enabled a plethora of transformations that would otherwise only be possible using transition metal catalysts. Of particular interest are the C-H bond activation and borylation reactions, which is the subject of this review. The FLP borylation chemistry is compared with the early borylation methodologies using strongly electrophilic borenium ions. We present the mechanism of the C-H borylation using inter- and intramolecular Lewis pairs, along with some applications of these transformations.

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Isodesmic Reactions in Catalysis – Only the Beginning?

Cited by 26 publications

References 68 publications

Isodesmic C–H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis

Isodesmic C–H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis

Teaching Aldehydes New Tricks Using Rhodium- and Cobalt-Hydride Catalysis

Boron Lewis Pair Mediated C–H Activation and Borylation

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