Sustainable preparation of photoactive indole-fused tetracyclic molecules: a new class of organophotocatalysts

Bae, Jaehahn; Iqbal, Naeem; Hwang, Ho Seong; Cho, Eun Jin

doi:10.1039/d2gc00542e

Cited by 16 publications

(11 citation statements)

References 79 publications

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“…16 It is worth noting that benzocoumarin is a biologically active compound present as core structure of many natural products such as urolithin A and alternariol. 17 In addition, when toluene (8) was subjected to optimized reaction conditions, it underwent the benzylic oxidation to afford benzaldehyde (9) and benzoic acid (2a) in 40% and 58% yields, respectively (Scheme 2b).…”

Section: Resultsmentioning

confidence: 99%

“…Over the last one and a half decades, visible light photocatalysis has emerged as a powerful sustainable tool for the activation of organic molecules toward a variety of chemical transformations 4 . Several metal‐based photocatalysts such as Bi, Ni, Ti, Fe, 3f Pt, 5 Cu, 6 Ru, 7 and Ir 8 complexes as well as various organo‐photocatalysts 3f,9 including eosin Y, 10 4CzIPN, 11 fluorenones, rose bengal, 3f thioxanthenone, 12 and tetraphenyl porphyrin (H 2 TPP) have been successfully applied in oxidation processes under light irradiation (Scheme 1a). 3f Another advantage of many of these photocatalytic systems is the use of nontoxic and abundant molecular oxygen as the oxidant, avoiding the generation of hazardous, toxic, and stoichiometric by‐products 13 .…”

Section: Methodsmentioning

confidence: 99%

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Organophotocatalytic oxidation of alcohols to carboxylic acids

Tambe

Cho

2022

Bulletin Korean Chem Soc

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A sustainable photochemical protocol for the oxidation of alcohols to ketones and carboxylic acids has been developed by using 2,4,6‐triphenylpyrylium tetrafluoroborate (TPPT) as organophotocatalyst and molecular oxygen as oxidant under visible light irradiation. The key reactive oxygen species, superoxide (O2•−) for the first oxidation step from alcohol to aldehyde and singlet oxygen (1O2) for the second oxidation step from aldehyde to carboxylic acid, were generated successfully by electron transfer and energy transfer pathways, respectively. A range of primary and secondary alcohols were converted to the corresponding carboxylic acids or ketones, and the optimized reaction conditions were applied to the synthesis of benzocoumarin.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Organophotocatalytic oxidation of alcohols to carboxylic acids

Tambe

Cho

2022

Bulletin Korean Chem Soc

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“…Cho and co-workers had identified tetracyclic indol-6-ones as a new scaffold for organophotocatalysis and desired a practical strategy for their construction and exploration. 29 In their recent report, they detailed the development of a carbonickelationbased cascade reaction that generates the tetracyclic core from readily synthesized phenylacetylene derivatives and commercially available arylboronic acids (Scheme 17). Two key components of their system were the use of TFE as the solvent and the PN ligand PyPhos.…”

Section: ■ Recent Reports On Ni-catalyzed Reactionsmentioning

confidence: 99%

Recent Advances in Nonprecious Metal Catalysis

Haibach

Shekhar

Ahmed

et al. 2023

Org. Process Res. Dev.

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Nonprecious-metal-catalyzed alternatives to powerful precious metal transformations are of increasing interest in academia and the pharmaceutical industry due to the lower cost, better sustainability, and lower toxicity. With the continual growth in the broad field of nonprecious metal catalysis (NPMC), we have chosen to highlight selected articles published from March to June 2022 which are intended to highlight examples of NPMC that we feel may be especially relevant to pharmaceutical development. We aim to inspire academic and industrial innovation in NPMC through the discussion herein.

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“…In this study, we investigated additional factors, other than the thermodynamic feasibility related to the redox potentials and excited energies, for increasing the photocatalytic e ciency by using two structurally similar organoPCs. A pentacyclic indole-fused compound (A) was newly synthesized, in which the molecular construct was based on benzo [5,6]indeno [1,2-b]indol-12(5H)-one, and the tetracyclic variant (B), previously developed by our group 21 , was used as the control organoPC (Fig. 1b).…”

Section: Introductionmentioning

confidence: 99%

Analysis of Organophotocatalyst-Substrate Interactions for Understanding Triplet-Triplet Back Energy Transfer

Yunjeong

Woo

Bae

et al. 2023

Preprint

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The excited energy levels of a photocatalyst (PC) and an organic substrate critically affect the feasibility of energy transfer (EnT) process. Despite having energy levels that are well-matched, the catalytic performance of the PC has not always been satisfactory, indicating there are other crucial factors that influence the catalytic efficiency and need to be considered. Finding additional critical factors can be challenging as negative factors often lead to unsuccessful reactions, making it difficult to conduct a thorough investigation. To address this challenge, we employed structurally similar indole-fused polycyclic complexes as organoPCs, which were developed by our laboratory for the study. Herein, we describe a binding interaction effect between a PC and a substrate for controlling the catalytic efficiency in an EnT-mediated DeMayo-type [2 + 2] cycloaddition process. A series of photophysical and computational investigations showed that the strong binding interaction of the PC with the substrate promotes the back triplet–triplet EnT process competently and thus deactivates the productive radical transformations. This finding provides an understanding of the inner-workings of EnT process, and will guide the rational design of new EnT processes. Furthermore, the excellent photocatalytic properties of the newly synthesized pentacyclic organoPC offer tremendous potential for applications in other photocatalytic reactions.

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Sustainable preparation of photoactive indole-fused tetracyclic molecules: a new class of organophotocatalysts

Abstract: An efficient and green preparation of photoactive indole-fused tetracyclic molecules and their applications as organophotocatalyst have been developed. Additive-free and air stable nickel catalysis of readily-prepared phthlimide derivatives in a...

Cited by 16 publications

References 79 publications

Organophotocatalytic oxidation of alcohols to carboxylic acids

Organophotocatalytic oxidation of alcohols to carboxylic acids

Recent Advances in Nonprecious Metal Catalysis

Analysis of Organophotocatalyst-Substrate Interactions for Understanding Triplet-Triplet Back Energy Transfer

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