Triplet-triplet annihilation upconversion (TTA-UC) has the potential to enhance photoredox catalysis yield. It includes a sensitizer and an annihilator. Efficient and stable annihilators are essential for photoredox catalysis, yet only a few examples are reported. Herein, we designed four novel pyrene annihilators (1, 2, 3 and 4) via introducing aryl-alkynyl groups onto pyrene to systematically modulate their singlet and triplet energies. Coupled with platinum octaethylporphyrin (PtOEP), the TTA-UC efficiency is enhanced gradually as the number of aryl-alkynyl group increases. When combining 4 with palladium tetraphenyl-tetrabenzoporphyrin (PdTPTBP), we achieved the highest red-to-green upconversion efficiency (22.4±0.3 %) (out of a 50 % maximum) so far. Then, this pair was used to activate photooxidation of aryl boronic acid under red light (630 nm), which achieved a great improved reaction yield compared to that activated by green light directly. The results not only provide a design strategy for efficient annihilators, but also show the advantage of applying TTA-UC into improving the photoredox catalysis yield.
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http://dx.doi.org/10.1002/chem.202302520 | DOI Listing |
ACS Cent Sci
January 2025
College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China.
Multicomponent reactions (MCRs), highly sought-after methods to produce atom-, step-, and energy-economic organic syntheses, have been developed extensively. However, catalytic asymmetric MCRs, especially those involving radical species, remain largely unexplored owing to the difficulty in stereoselectively regulating the extraordinarily high reactivity of open-shell radical species. Herein, we report a conceptually novel catalytic asymmetric three-component radical cascade reaction of readily accessible glycine esters, α-bromo carbonyl compounds and 2-vinylcyclopropyl ketones via synergistic photoredox/Brønsted acid catalysis, in which three sequential C-C (σ/π/σ) bond-forming events occurred through a radical addition/ring-opening/radical-radical coupling protocol, affording an array of valuable enantioenriched unnatural α-amino acid derivatives bearing two contiguous stereogenic centers and an alkene moiety in moderate to good yield with high diastereoselectivity, excellent enantioselectivity and good -dominated geometry under mild reaction conditions.
View Article and Find Full Text PDFOrg Lett
January 2025
School of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China.
The catalytic asymmetric multicomponent acylation/rearrangement/cyclization of alkenylfurans with acyl oxime esters/arylamines or acyl oxime esters/arylamines/hydroxylamine has been developed. This method employs synergistic photoredox/Brønsted acid catalysis, enabling the efficient and versatile synthesis of multifunctionalized [3.2.
View Article and Find Full Text PDFMolecules
January 2025
Aix Marseille Univ, CNRS, ICR, 13013 Marseille, France.
In this study we report on the efficiency of a furane-indole-chromenone-based organic derivative () as a photocatalyst in the α-arylation of enol acetate upon LED irradiation at 405 nm, and as a photoinitiator/photocatalyst in the free radical polymerization of an acrylate group in the presence of -(4--butylphenyl)iodonium hexafluorophosphate (Iod) as an additive, or in the presence of both Iod and ethyl-4-(dimethyl amino) benzoate (EDB) under LED irradiation at 365 nm. The photochemical properties of this new light-sensitive compound are described, and the wide redox window (3.27 eV) and the high excited-state potentials / (+2.
View Article and Find Full Text PDFJ Med Chem
January 2025
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
The hypoxic environment of solid tumors significantly diminishes the therapeutic efficacy of oxygen-dependent photodynamic therapy. Developing efficient photosensitizers that operate photoredox catalysis presents a promising strategy to overcome this challenge. Herein, we report the rational design of two rhenium(I) tricarbonyl complexes ( and ) with electron donor-acceptor-donor configuration.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Department of Chemistry, Indian Institute of Technology Ropar (IIT Ropar), Rupnagar, Punjab-140 001, India.
Low-energy photoredox catalysis has gained significant attention in developing organic transformations due to its ability to achieve high penetration depth and minimum health risks. Herein, we disclose a red-light ( = 640 nm)-mediated C-3 formylation of indoles utilizing a helical carbenium ion as a photocatalyst and 2,2-dimethoxy-,-dimethylethanamine as a formylating source. These protocols exhibit a broad substrate scope under mild conditions with efficient scalability for the synthesis of C-3 formylated indoles.
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