Photo catalysis is a powerful tool in organic chemical synthesis. The first synthetic application of photo catalysis was in the late 1980s. However, there was a 20-year gap before the advantages were recognized, hampered by the using of high-energy light, coupled with the disparate absorption properties of organic molecules. Over the last decade, with the discovery of absorptive organometallic complexes and organic dyes, photoredox catalysis which utilizes visible light to enable single-electron transfer between photo-excitable catalysts and organic molecules, has seen broad adoption for the activation and transformation of organic substrates, as reflected by the boosted number of publications each year.
The widespread adoption and growth of visible light photoredox catalysis can, in part, be attributedto the well-established photophysical properties of photoredox catalysts. These catalysts, often polypyridyl complexes of ruthenium or iridium, can be excited by low energy visible light, with its photonic energy selectively targeting the catalysts over the organic and organometallic substrates in solution. Many transition-metal complexes and organocatalysts capable of initiating radical formation in the presence of visible light have been shown to facilitate a wide array of synthetic transformations including but not limited to cross-coupling, C-H functionalization, alkene and arene functionalization, and trifluoromethylation.
Carbon-Carbon Bond Formation
Over the last half century, the advent and development of palladium-catalyzed cross-coupling has revolutionized the means by which chemists synthesize new molecules. Groundbreaking work by Heck, Negishi, and Suzuki, among many others, has allowed for the construction of unprecedented molecular complexity from simple and abundant starting materials. However, despite the widespread success of palladium-catalyzed cross-couplings in the forging of bonds to sp2-hybridized carbon centers, significant limitations remain with respect to the coupling of sp3-hybridized fragments. Substantial progress toward this challenging objective has been made in the area of nickel catalysis, which, when compared to palladium, undergoes a more rapid oxidative addition into alkyl electrophiles and suffers less from deleterious β-hydride elimination with aliphatic ligands. While these developments have broadened the spectrum of strategies at the disposal of the modern chemist, the desire to expand the scope of coupling partners to simpler, cheaper, and more abundant starting materials has pushed the frontiers of catalysis. In this context, photoredox catalysis has played an integral role incorporating native functional groups in novel bond disconnections.
Decarboxylative coupling
C-H cross-coupling
Heteroatom Arylations
Transition metal catalysis has dramatically reshaped the landscape of chemical synthesis not only in the construction of all-carbon frameworks, but in the forging of carbon-heteroatom bonds as well. Given the competence of photoredox catalysis to enable nickel to forge historically challenging carbon-carbon bonds through energy-transfer and/or electron-transfer mechanisms, similar elementary steps have been shown to enable otherwise elusive carbon−heteroatom bond formations.
C-N coupling
C-O coupling
Medicilon Photochemistry Platform
Medicilon has been actively developing new technologies platforms over the years, integrating emerging methods of green chemistry into its services, using currently popular photoredox chemistry, electrochemisty, catalyst screening, continuous reactions, etc., to provide our customers with high-quality economic solutions. Our photochemistry team has:
- Rich experience in different types of photochemistry reactions;
- Full capacity for the synthesis of variety catalysts for photocatalytic reactions;
- Strong expertise in photoredox chemistry.
Equipments
References:
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[5] Megan H Shaw,et al. Native functionality in triple catalytic cross-coupling: sp³ C-H bonds as latent nucleophiles. Science. 2016 Jun 10;352(6291):1304-8. doi: 10.1126/science.aaf6635.
[6] Chip Le,et al. Selective sp³ C-H alkylation via polarity-match-based cross-coupling. Nature. 2017 Jul 6;547(7661):79-83. doi: 10.1038/nature22813.
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[9] Amy Y Chan, et al. Metallaphotoredox: The Merger of Photoredox and Transition Metal Catalysis. Chem Rev. 2022 Jan 26;122(2):1485-1542. doi: 10.1021/acs.chemrev.1c00383.
