Hybrid cycloolefin ligands for palladium–olefin cooperative catalysis

Zheng, Ya-Xin; Jiao, Lei

doi:10.1038/s44160-021-00019-8

Cited by 18 publications

(12 citation statements)

References 42 publications

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“…More recently, our group reported that the Catellani-type reaction can proceed without the participation of NBE by the development of an unstrained hybrid cycloolefin ligand, which extended the concept of Pd/NBE catalysis to more general Pd/olefin catalysis. 20…”

Section: Introductionmentioning

confidence: 99%

Functionalized Cycloolefin Ligand as a New Solution to Ortho-Constraint in the Catellani-Type Reaction

Wang

Jiao

2023

Preprint

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The Catellani reaction, i.e., the Pd/NBE catalysis, has been evolved into a versatile approach to multisubstituted arenes via the ortho-functionalization/ipso-termination process of a haloarene. Despite significant advances over the past 25 years, this reaction still suffered from an intrinsic limitation in the substitution pattern of the aryl halide, referred to as “ortho-constraint”. When an ortho substituent is absent, the haloarene substrate often fails to undergo effective mono ortho-functionalization process, and either ortho-difunctionalization products or NBE-embedded byproducts predominate. To tackle this challenge, structurally-modified NBEs (smNBEs) have been developed, which were proved effective for the mono ortho-aminative, -acylative, and -arylative Catellani reactions of ortho-unsubstituted haloarenes. However, the smNBE strategy is incompetent for solving the ortho-constraint in Catellani reactions with ortho-alkylation, and to date there lacks a general solution to this challenging but synthetically useful transformation. Recently, our group developed the Pd/olefin catalysis, in which an unstrained hybrid cycloolefin ligand served as a covalent catalytic module to enable the ortho-alkylative Catellani reaction without an NBE mediator. In this work, we show that this chemistry could afford a new solution to ortho-constraint in the Catellani reaction. A functionalized hybrid cycloolefin ligand bearing an amide group as the internal base was designed, which allowed for mono ortho-alkylative Catellani reaction of iodoarenes suffering from ortho-constraint before. Mechanistic study revealed that the newly designed ligand is capable of both accelerating the C−H activation and inhibiting side reactions, which accounts for its superior performance. The present work showcased the uniqueness of the Pd/olefin catalysis as well as the power of rational ligand design in metal catalysis.

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Section: Introductionmentioning

confidence: 99%

Functionalized Cycloolefin Ligand as a New Solution to Ortho-Constraint in the Catellani-Type Reaction

Wang

Jiao

2023

Preprint

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“…In 2017, the Glorius group reported an elegant approach for o -amidation of phenols, using a rhodium catalyst and a new oxanorbornene (NBE2) as the bicyclic olefin mediator . The key feature of the NBE2 structure is its rigidity, which precludes β-hydride elimination and facilitates ortho functionalization (Figure a). , Protons H a and H b do not undergo β-hydride elimination due to a lack of the requisite synperiplanar arrangement and geometric constraints (c.f., Bredt’s rule) respectively …”

Section: Introductionmentioning

confidence: 99%

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

et al. 2022

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A catalytic system is discovered for the intramolecular C–H amidation of N-phenoxy acetamide derivatives. Herein, a cobalt catalyst has been employed for the olefin-mediated ortho C–H functionalization. Moreover, a monocyclic olefin, maleimide, has been used as a transient mediator instead of well-established bicyclic norbornenes. Maleimide promotes a Co(III) intermediate to undergo oxidative addition into the O–N bond to form a Co(V) nitrene species and subsequently directs nitrene addition to the ortho position. Mechanistic study and density functional theory (DFT) study support the proposed mechanism. The products derived from this methodology have been demonstrated as a ligand in the C–H olefination reaction. Furthermore, the synthetic utility of this methodology was demonstrated via the ortho-amidation of estrone.

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“…Additionally, in 2022 the group of Jiao introduced unstrained olefin ligands that bear a S coordination site for use in the Pd-catalysed Catellani reaction. [15] We hypothesized that by using our Pd/ S,O-ligand catalytic system in conjunction with the appropriate choice of the NBE mediator [13,16] could overcome the previously mentioned limitations for the meta-arylation of alkoxyarenes. Herein, we report a general and efficient CÀ H arylation of alkoxyarenes with non-conventional site-selectivity, promoted by Pd/NBE catalysis using the Pd/S,Oligand catalytic system (Scheme 1b).…”

Section: Introductionmentioning

confidence: 99%

“…A unique feature of the Pd/S,O‐ligand system is it's high catalytic activity, allowing for the functionalization of aniline and anisole derivatives bearing several electron withdrawing substituents, substrates that are unreactive using other catalytic systems. Additionally, in 2022 the group of Jiao introduced unstrained olefin ligands that bear a S coordination site for use in the Pd‐catalysed Catellani reaction [15] . We hypothesized that by using our Pd/S,O‐ligand catalytic system in conjunction with the appropriate choice of the NBE mediator [13, 16] could overcome the previously mentioned limitations for the meta ‐arylation of alkoxyarenes.…”

Section: Introductionmentioning

confidence: 99%

S,O‐Ligand Promoted meta‐C−H Arylation of Anisole Derivatives via Palladium/Norbornene Catalysis

et al. 2022

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Reversing the conventional site-selectivity of CÀ H activation processes provides new retrosynthetic disconnections to otherwise unreactive bonds. Here, we report a new catalytic system based on palladium/ norbornene and an S,O-ligand for the meta-CÀ H arylation of aryl ethers that significantly outperforms previously reported systems. We demonstrate the unique ability of this system to employ alkoxyarene substrates bearing electron donating and withdrawing substituents. Additionally, ortho-substituted aryl ethers are well tolerated, overcoming the "ortho constraint", which is the necessity to have a meta-substituent on the alkoxyarene to achieve high reaction efficiency, by enlisting novel norbornene mediators. Remarkably, for the first time the monoarylation of alkoxyarenes is achieved efficiently enabling the subsequent introduction of a second, different aryl coupling partner to rapidly furnish unsymmetrical terphenyls. Further insight into the reaction mechanism was achieved by isolation and characterization of some Pd-complexesbefore and after meta CÀ H activation-prior to evaluation of their respective catalytic activities.

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Hybrid cycloolefin ligands for palladium–olefin cooperative catalysis

Cited by 18 publications

References 42 publications

Functionalized Cycloolefin Ligand as a New Solution to Ortho-Constraint in the Catellani-Type Reaction

Functionalized Cycloolefin Ligand as a New Solution to Ortho-Constraint in the Catellani-Type Reaction

Breaking the Monotony: Cobalt and Maleimide as an Entrant to the Olefin-Mediated Ortho C–H Functionalization

S,O‐Ligand Promoted meta‐C−H Arylation of Anisole Derivatives via Palladium/Norbornene Catalysis

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