Efficient metal-free visible light photocatalytic aromatization of azaheterocyles

Chhetri, Karan; Bhuyan, Samuzal; Mandal, Swarup; Chhetri, Sonia; Lepcha, Pema Tshering; Lepcha, Sonam W.; Basumatary, Joneswar; Roy, Biswajit

doi:10.1016/j.crgsc.2021.100135

Cited by 6 publications

(5 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Based on these experiments and on previous literature reports, [62,77,82,83] the following mechanism is proposed (Scheme 5). Upon irradiation, the electrons in the CTF will be excited, resulting in the transfer of electrons from the valence band to the conduction band.…”

Section: Resultssupporting

confidence: 53%

“…[80] Similarly, using 2,2,6,6-tetramethylpiperidine (TEMP) as a spin trap, the generation of singlet oxygen was confirmed, as the free radical TEMPO was generated (Figure 5e). [81] Based on these experiments and on previous literature reports, [62,77,82,83] the following mechanism is proposed (Scheme 5). Upon irradiation, the electrons in the CTF will be excited, resulting in the transfer of electrons from the valence band to the conduction band.…”

Section: Application As Photocatalysts For the Aromatization Of N-het...mentioning

confidence: 57%

“…For this reason, catalytic methods utilizing oxygen or air and a catalyst such as Fe(ClO 4 ) 3 , [59] or N ‐hydroxyphthalimide (NHPI) [60] have been developed. Moreover, photocatalysts such as eosin Y bis(tetrabutylammonium salt) (TBA‐eosin Y) [61] and acridinium dyes [62] have recently been described. Although these methods do not require the addition of stoichiometric oxidants, the catalysts still need to be separated from the reaction mixture and in most cases they are not recyclable.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Development of Porous Organic Polymers as Metal‐Free Photocatalysts for the Aromatization of N‐Heterocycles

Debruyne,

Raeymackers,

Vrielinck

et al. 2023

ChemCatChem

View full text Add to dashboard Cite

Porous organic polymers (POPs), and especially covalent triazine frameworks (CTFs), are being developed as the next generation of metal‐free heterogeneous photocatalysts. However, many of the current synthetic routes to obtain these photoactive POPs require expensive monomers and rely on precious metal catalysts, thus hindering their widespread implementation. In this work, a range of POPs was synthesized from simple unfunctionalized aromatic building blocks, through Lewis acid‐catalyzed polymerization. The obtained materials were applied, for the first time, as heterogeneous photocatalysts for the aromatization of N‐heterocycles. With the use of the most active material, denoted as CTF‐Pyr, which consists of photoactive pyrene and triazine moieties, a wide range of pyridines, dihydroquinoline‐5‐ones, tetrahydroacridine‐1,8‐diones and pyrazoles were obtained in excellent yields (70–99 %). Moreover, these reactions were carried out under very mild conditions using air and at room temperature, highlighting the potential of these materials as catalysts for green transformations.

show abstract

Section: Resultssupporting

confidence: 53%

Section: Application As Photocatalysts For the Aromatization Of N-het...mentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Development of Porous Organic Polymers as Metal‐Free Photocatalysts for the Aromatization of N‐Heterocycles

Debruyne,

Raeymackers,

Vrielinck

et al. 2023

ChemCatChem

View full text Add to dashboard Cite

show abstract

“…In order to do that we preferred to explore the possibility of using the visible light photocatalytic method by choosing easily synthesizable benzyl ether of high boiling heptanol, 2 , as our model compound so that the isolated yield of deprotected alcohol could be measured without worrying about evaporative weight loss during workup. To start with we irradiated methanolic solution of 2 with blue LED light in presence of 1 mol% of a recently developed photo‐catalyst A, [21,22a,b] and 0.5 equiv. of DDQ in ambient condition and open air.…”

Section: Resultsmentioning

confidence: 99%

Efficient Greener Visible‐Light‐Catalyzed Debenzylation of Benzyl Ethers and Esters: A Gateway to Wider Exploitation of Stable Benzyl Protecting Groups

et al. 2022

Self Cite

View full text Add to dashboard Cite

A non-hydrogenolytic mild deprotection strategy for stable benzyl protection of hydroxyl group is one of the long-cherished goals in multistep synthesis involving carbohydrates or compounds with multiple hydroxyl groups. A greener organo-photocatalytic method has been developed for mild and efficient visible light catalytic deprotection of benzyl group from benzyl ether and benzyl ester. The newly developed method in ambient condition with only 1 mol% of catalyst loading can efficiently remove highly stable benzyl protection from ethers and esters of wide substrate scope with excellent functional group tolerance, thus proved to be suitable for final stage deprotection. Employment of molecular oxygen as terminal oxidant and excellent yield in the multigram scale reaction signifies the eco-friendliness, robustness and industrial applicability of the method.

show abstract

“…Other N-heterocyclic compounds oxidized under aerobic conditions and irradiation with visible light were 1,2-and 1,4-dihydropyridines (Scheme 10a,b), hexahydroacridinediones (Scheme 10c) and polyhydroquinolines (Scheme 10d), employing a 1,8-dimethoxy-substituted acridinium ion 18 as catalyst, leading to the corresponding aromatic N-heterocycles 19-22 in excellent yields [81]. The proposed mechanism for these transformations, exemplified in the case of dihydropyridine, is shown in Scheme 11.…”

Section: Oxidative Dehydrogenation Of C-n Bonds 21 Homogeneous Oxidative Dehydrogenation Of C-n Bondsmentioning

confidence: 99%

Visible Light-Induced Aerobic Oxidative Dehydrogenation of C–N/C–O to C=N/C=O Bonds Using Metal-Free Photocatalysts: Recent Developments

Torregrosa-Chinillach

Chinchílla

2022

Molecules

View full text Add to dashboard Cite

Performing synthetic transformation using visible light as energy source, in the presence of a photocatalyst as a promoter, is currently of high interest, and oxidation reactions carried out under these conditions using oxygen as the final oxidant are particularly convenient from an environmental point of view. This review summarizes the recent developments achieved in the oxidative dehydrogenation of C–N and C–O bonds, leading to C=N and C=O bonds, respectively, using air or pure oxygen as oxidant and metal-free homogeneous or recyclable heterogeneous photocatalysts under visible light irradiation.

show abstract

Efficient metal-free visible light photocatalytic aromatization of azaheterocyles

Cited by 6 publications

References 47 publications

Development of Porous Organic Polymers as Metal‐Free Photocatalysts for the Aromatization of N‐Heterocycles

Development of Porous Organic Polymers as Metal‐Free Photocatalysts for the Aromatization of N‐Heterocycles

Efficient Greener Visible‐Light‐Catalyzed Debenzylation of Benzyl Ethers and Esters: A Gateway to Wider Exploitation of Stable Benzyl Protecting Groups

Visible Light-Induced Aerobic Oxidative Dehydrogenation of C–N/C–O to C=N/C=O Bonds Using Metal-Free Photocatalysts: Recent Developments

Contact Info

Product

Resources

About