Efficient Palladium‐Catalyzed Aerobic Arylative Carbocyclization of Enallenynes

Liu, Jie; Ricke, Alexander; Yang, Bin; Bäckvall, Jan‐Erling

doi:10.1002/ange.201810501

Cited by 18 publications

(3 citation statements)

References 80 publications

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“…In analogy with our previous report, [15] there was a rate enhancement with the hybrid catalyst compared to the use of Co(salophen) and quinone as separate molecules as shown in Figure 2. Co(salophen)‐HQ hybrid ( Cat.…”

Section: Methodssupporting

confidence: 81%

“…During the past decade, our research group has been involved in the development of palladium‐catalyzed oxidative carbocyclizations of allenes bearing an additional unsaturated moiety, such as an olefin, alkyne, or allene [16] . Interestingly, we found that an assisting group (AG), [17] such as an olefin, alkyne or hydroxyl group, is required to make 6‐membered rings [8e,h, 15, 18] from enallenes and allenynes and to make 7‐membered rings from bisallenes due to the initial allenic C−H cleavage by Pd II (Scheme 2 a). Afterward, cascade carbocyclization and transmetallation with a nucleophile can occur and give the cyclic product.…”

Section: Methodsmentioning

confidence: 99%

“…Later on, an improved hybrid Schiff base‐hydroquinone [Co(salophen)‐HQ] as a redox relay catalyst for aerobic oxidation was reported [14] . The latter bifunctional catalyst led to a faster reaction rate compared to the system with the quinone and metal‐macrocycle as separate molecules in Pd‐catalyzed aerobic carbocyclization of enallenynes and dienallenes [8h, 15] …”

Section: Methodsmentioning

confidence: 99%

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Efficient Palladium‐Catalyzed Aerobic Oxidative Carbocyclization to Seven‐Membered Heterocycles

Liu

Bäckvall

2020

Chemistry A European J

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The use of molecular oxygen in palladium‐catalyzed oxidation reactions is highly widespread in organic chemistry. However, the direct reoxidation of palladium by O2 is often kinetically unfavored, thus leading the deactivation of the palladium catalyst during the catalytic cycle. In the present work, we report a highly selective palladium‐catalyzed carbocyclization of bisallenes to seven‐membered heterocycles under atmospheric pressure of O2. The use of a homogenous hybrid catalyst (Co(salophen)‐HQ, HQ=hydroquinone) significantly promotes efficient electron transfer between the palladium catalyst and O2 through a low‐energy pathway. This aerobic oxidative transformation shows broad substrate scope and functional group compatibility and allowed the preparation of O‐containing seven‐membered rings in good yields in most cases.

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Section: Methodssupporting

confidence: 81%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Efficient Palladium‐Catalyzed Aerobic Oxidative Carbocyclization to Seven‐Membered Heterocycles

Liu

Bäckvall

2020

Chemistry A European J

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Palladium Catalysis for Aerobic Oxidation Systems Using Robust Metal–Organic Framework

Jiang

Li²,

Liao³

et al. 2019

Angewandte Chemie

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Described here is a new and viable approach to achieve Pd catalysis for aerobic oxidation systems (AOSs) by circumventing problems associated with both the oxidation and the catalysis through an all‐in‐one strategy, employing a robust metal–organic framework (MOF). The rational assembly of a PdII catalyst, phenanthroline ligand, and CuII species (electron‐transfer mediator) into a MOF facilitates the fast regeneration of the PdII active species, through an enhanced electron transfer from in situ generated Pd0 to CuII, and then CuI to O2, trapped in the framework, thus leading to a 10 times higher turnover number than that of the homogeneous counterpart for Pd‐catalyzed desulfitative oxidative coupling reactions. Moreover, the MOF catalyst can be reused five times without losing activity. This work provides the first exploration of using a MOF as a promising platform for the development of Pd catalysis for AOSs with high efficiency, low catalyst loading, and reusability.

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Iron(II)‐Catalyzed Biomimetic Aerobic Oxidation of Alcohols

2020

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We report the first FeII‐catalyzed biomimetic aerobic oxidation of alcohols. The principle of this oxidation, which involves several electron‐transfer steps, is reminiscent of biological oxidation in the respiratory chain. The electron transfer from the alcohol to molecular oxygen occurs with the aid of three coupled catalytic redox systems, leading to a low‐energy pathway. An iron transfer‐hydrogenation complex was utilized as a substrate‐selective dehydrogenation catalyst, along with an electron‐rich quinone and an oxygen‐activating Co(salen)‐type complex as electron‐transfer mediators. Various primary and secondary alcohols were oxidized in air to the corresponding aldehydes or ketones with this method in good to excellent yields.

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Efficient Palladium‐Catalyzed Aerobic Arylative Carbocyclization of Enallenynes

Cited by 18 publications

References 80 publications

Efficient Palladium‐Catalyzed Aerobic Oxidative Carbocyclization to Seven‐Membered Heterocycles

Efficient Palladium‐Catalyzed Aerobic Oxidative Carbocyclization to Seven‐Membered Heterocycles

Palladium Catalysis for Aerobic Oxidation Systems Using Robust Metal–Organic Framework

Iron(II)‐Catalyzed Biomimetic Aerobic Oxidation of Alcohols

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