Csp3–Csp3Bond Cleavage in the Palladium-Catalyzed Aminohydroxylation of Allylic Hydrazones Using Atmospheric Oxygen as the Sole Oxidant

Chen, Yu‐Chen; Zhu, Ming-Kui; Loh, Teck‐Peng

doi:10.1021/acs.orglett.5b01127

Cited by 23 publications

(5 citation statements)

References 82 publications

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“…Despite these significant developments, there still remains ample room for further improvement especially in terms of reaction diversity, applicability, and practicality. With our continuing interest in C–N bonds and N -heterocycles construction, we would like to report our recent advancement in visible-light-promoted carboimination of unactivated alkenes for the construction of densely functionalized pyrroline derivatives.…”

Section: Introductionmentioning

confidence: 99%

Visible-Light-Promoted Carboimination of Unactivated Alkenes for the Synthesis of Densely Functionalized Pyrroline Derivatives

et al. 2016

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An efficient strategy which integrates visible-light-induced iminyl-radical formation with carboimination of unactivated alkenes has been developed for the easy access of densely functionalized pyrroline derivatives. With fac-[Ir(ppy)3] as photoredox catalyst, the acyl oximes were converted into iminyl radical intermediates by one electron reduction, and evolve through a cascade of intramolecular cyclization and intermolecular carbon radical trapping to give the functionalized pyrrolines. The utilization of silyl enol ethers as coupling partners not only allows the introduction of synthetically useful ketone functionalities but also renders catalyst regeneration without any external reductants. This protocol is characterized by its mild reaction conditions and the tolerance of a broad range of functionalities.

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Section: Introductionmentioning

confidence: 99%

Visible-Light-Promoted Carboimination of Unactivated Alkenes for the Synthesis of Densely Functionalized Pyrroline Derivatives

et al. 2016

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“…The reaction without any photocatalyst under the Ultra-Vitalux lamp gave pyrazole 2a in significantly lower yield and longer reaction times (irradiation for 24 h) (Scheme ). The global process using the photoredox catalyst opens the possibility of using the formyl group as novel photoremovable directing groups under mild reaction conditions …”

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Aldehydes as Photoremovable Directing Groups: Synthesis of Pyrazoles by a Photocatalyzed [3+2] Cycloaddition/Norrish Type Fragmentation Sequence

et al. 2021

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A straightforward methodology for the regioselective synthesis of pyrazoles has been developed by a domino sequence based on a photoclick cycloaddition followed by a photocatalyzed oxidative deformylation reaction. Distinguishing features of this protocol include an unprecedented photoredox-catalyzed Norrish type fragmentation under green-light irradiation and the use of α,β-unsaturated aldehydes as synthetic equivalents of alkynes, where the aldehyde is acting as a novel photoremovable directing group.

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“…Nevertheless, most of the reported approaches rely on the catalytic 5-exo-trig or 6-endo-trig ring closure in the realm of β,γ-unsaturated hydrazone chemistry (see Scheme b) . The catalyst-controlled aerobic radical cyclization of hydrazones for the synthesis of pyrazoles via the cleavage of the CC double bond has rarely been exploited so far. , Therefore, the fabrication of pyrazoles with readily accessible starting materials in a controllable manner would be greatly desirable.…”

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Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant C═C Bond Cleavage

et al. 2020

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A Cu-catalyzed aerobic oxidative cyclization of β,γ-unsaturated hydrazones for the preparation of pyrazole derivatives has been developed. The hydrazonyl radical promoted the cyclization, along with a concomitant CC bond cleavage of β,γ-unsaturated hydrazones. This process has been verified via several control experiments, including a radical-trapping study, an 18O-labeling method, and the identification of the possible byproducts. The advantages of this reaction include operational simplicity, a broad reaction scope, and a mild selective reaction process.

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C_sp³–C_sp³Bond Cleavage in the Palladium-Catalyzed Aminohydroxylation of Allylic Hydrazones Using Atmospheric Oxygen as the Sole Oxidant

Abstract: A C-C bond cleavage was observed in the palladium-catalyzed aminohydroxylation of allylic hydrazones, using atmospheric oxygen as the sole oxidant. This reaction could also proceed in a one-pot manner, starting from keto-alkene compounds and phenylhydrazine.

Cited by 23 publications

References 82 publications

Visible-Light-Promoted Carboimination of Unactivated Alkenes for the Synthesis of Densely Functionalized Pyrroline Derivatives

Visible-Light-Promoted Carboimination of Unactivated Alkenes for the Synthesis of Densely Functionalized Pyrroline Derivatives

Aldehydes as Photoremovable Directing Groups: Synthesis of Pyrazoles by a Photocatalyzed [3+2] Cycloaddition/Norrish Type Fragmentation Sequence

Copper-Catalyzed Aerobic Cyclization of β,γ-Unsaturated Hydrazones with Concomitant C═C Bond Cleavage

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