Catalyst- and additive-free Baeyer–Villiger-type oxidation of α-iodocyclopentenones to α-pyrones: using air as the oxidant

Zhou, Yuanyuan; Ling, Xiangxiang; Rao, Weidong

doi:10.1039/c9gc02725d

Cited by 7 publications

(4 citation statements)

References 81 publications

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“…Likewise, a catalyst-and additive-free Baeyer-Villiger-type oxidation of α-iodocyclopentenones 180 to pyrones 182 using air as a green oxidant was reported by Rao et al (Scheme 36). [62] This reaction exhibits an excellent functional group tolerance, and the synthetic utility was demonstrated by a large-scale synthesis of a pyrone derivative 182. Control experiments indicated that the role of molecular oxygen as the oxidant is crucial for the success of the Baeyer-Villiger-type oxidation.…”

Section: Transition-metal-free Synthesismentioning

confidence: 99%

“…Catalyst-and additive-free Baeyer-Villiger oxidation of iodocyclopentenones 180. [62] the nucleophile occurs by an inner-sphere mechanism. This method gave access to doubly unsaturated acid derivatives 187 or 188 with high functional group tolerance and control of stereochemistry (2E,4E 187 vs. 2Z,4E 188), the latter being easily controlled by variation of the temperature before work-up.…”

Section: Ring-opening Reactionsmentioning

confidence: 99%

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2‐Pyrone – A Privileged Heterocycle and Widespread Motif in Nature

et al. 2021

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In memory of Klaus HafnerThe 2-pyrone moiety can be found in a large number of natural products with a wide range of biological activities, including antibiotic, antifungal, cytotoxic, neurotoxic, phytotoxic, antiinflammatory and cardiotonic effects. With its heterocyclic structure encompassing the chemical nature of conjugated dienes, lactones, Michael acceptors and arenes, it can undergo a great variety of transformations such as cycloadditions, ringopening reactions, cross-couplings and lactamizations. Thus, 2-pyrones represent valuable synthetic precursors and worthwhile targets in organic, polymer, and medical chemistry. Owing to its exquisite chemical and physical properties, the synthesis and further transformations of 2-pyrones have attracted considerable attention over the past decade, showcasing transition metal and metal free strategies and using readily available starting materials, notably those stemming from renewable resources.

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Section: Transition-metal-free Synthesismentioning

confidence: 99%

Section: Ring-opening Reactionsmentioning

confidence: 99%

2‐Pyrone – A Privileged Heterocycle and Widespread Motif in Nature

et al. 2021

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“…In recent years, researchers have adopted an aldehyde/O 2 strategy to efficiently produce ε-CL under relatively mild conditions. 11 Aldehydes such as benzaldehyde, acetoaldehyde, and m-chloro-benzaldehyde serve as co-oxidants or sacrificial agents. 12−15 For instance, Han et al used iron-based metalloporphyrin (FPOP-3) to catalyze the oxidation of CyO and obtained a 98% yield of ε-CL.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The main process is based on the Baeyer–Villiger oxidation developed in 1899 by Adolf von Baeyer and Victor Villiger. − In this process, cyclohexanone (CyO) as the raw material and organic peroxy acid/hydrogen peroxide as oxidant were used. − Although this method is highly efficient, it is a potentially hazardous process. In recent years, researchers have adopted an aldehyde/O 2 strategy to efficiently produce ε-CL under relatively mild conditions . Aldehydes such as benzaldehyde, acetoaldehyde, and m -chloro-benzaldehyde serve as co-oxidants or sacrificial agents. − For instance, Han et al used iron-based metalloporphyrin (FPOP-3) to catalyze the oxidation of CyO and obtained a 98% yield of ε-CL .…”

Section: Introductionmentioning

confidence: 99%

Catalytic Synthesis of Lactones from Alkanes in the Presence of Aldehydes and Carbon Nanotubes

Huang

Bai

Feng

et al. 2022

ACS Sustainable Chem. Eng.

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The catalytic synthesis of lactones from alkanes is a novel strategy from the viewpoint of environmentally benign technology. In this work, we propose a new protocol of using a typical alkane (cyclohexane, CyH) as a substrate to produce lactone (ε-caprolactone, ε-CL) in the presence of carbon nanotubes (CNTs) and aldehydes. The results demonstrated that CNTs could be used as an efficient catalyst for the production of ε-CL. Nitrogen doping would greatly enhance the activity, with 26.2% conversion of CyH and 87% selectivity of ε-CL. The specific N dopants served as complex active sites for improving the catalytic efficiency of NCNTs with an optimum content of N (3.38 atom %). Further investigations revealed that the ratio of pyridine N/ quaternary N probably played a significant role in the facilitation of this reaction, which displayed a linear relationship with the specific activity of NCNTs. A mechanistic study demonstrated that the activation of benzaldehyde for the production of carbonyl radicals was considered as the initial reaction, which activated CyH molecules to produce alkyl radicals, thus promoting the oxidation of CyH. The intermediate product CyO was found to be the main precursor of ε-CL, and during the reaction, cyclohexanol (Cy−OH) would likely be transformed into CyO.

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