Unmasking aryl thianthrenium salts in cells - Nature Synthesis

Nature Synthesis - Unmasking aryl thianthrenium salts in cells

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Photoredox Unmasking of Aromatic C–H Bonds in Living Environments Enabled by Thianthrenium Salts

Prodrug strategies traditionally rely on masking polar functional groups of bioactive molecules with protecting units that can be removed by specific stimuli in biological settings. Here, we introduce an alternative uncaging approach that bypasses the need for heteroatom handles, based on reversible masking of aromatic C–H bonds with thianthrenium groups. Unmasking is triggered by low-energy photoredox activation, which generates aryl radicals that are rapidly reduced by endogenous bioreductants to restore the native C–H bond. Beyond establishing the feasibility of photoredox radical chemistry in living cells, we demonstrate a proof-of-concept application of this strategy for the modulation of activity of antifungal agents.

pubs.acs.org

Photoredox Unmasking of Aromatic C–H Bonds in Living Environments Enabled by Thianthrenium Salts

Prodrug strategies traditionally rely on masking polar functional groups of bioactive molecules with protecting units that can be removed by specific stimuli in biological settings. Here, we introduce...

pubs.acs.org

Red-shifted photoredox generation and trapping of alkyl radicals towards bioorthogonality

The photocatalytic generation and trapping of alkyl radicals is a powerful synthetic tool in organic chemistry, but it remains underexplored in biological settings. Here, we present two photoredox…

pubs.rsc.org

Breaking Kasha’s Rule to Enable Higher Reactivity in Photoredox Catalysis

Nearly all photochemical transformations known to date follow Kasha’s rule, implying that reactions occur only from the lowest electronically excited state of a given spin multiplicity due to the fast...

bit.ly

José Luis Mascareñas, Premio Rei Jaume I en Investigación Básica

El investigador del Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CiQUS) y catedrático de la Universidade de Santiago de Compostela (USC), José Luis Mascareñas Cid,

usc.es

Rapid Access to Conjugated Z,Z,Z‐Trienes

Z,Z,Z-triene: A novel method to facilitate rapid access to the otherwise inaccessible conjugated Z,Z,Z-triene motif is reported.

doi.org

Preassembly‐Controlled Radical Recombination at Bismuth: Decarboxylative C─N Coupling with Sulfonamides

Radical processes involving bismuth hold great potential, but innovative strategies are required to control the reactivity of bismuth intermediates. Herein, we report a direct photochemical decarboxy...

doi.org

Methane Beryllation Catalyzed by a Base Metal Complex

The homogeneous catalytic functionalization of methane is extremely challenging due to the relative nonpolarity and high C–H bond strength of this hydrocarbon. Here, using catalytic quantities (10 mol...

pubs.acs.org

A three-step strategy for the conversion of pyridines into benzonitriles - Nature Synthesis

Bioisosteric replacement is vital in drug discovery; however, substituting core ring structures is challenging. Now, a strategy that converts pyridines into benzonitriles, via N-oxidation, photochemic...

nature.com

Excited Organic Radicals in Photoredox Catalysis

Many important synthetic-oriented works have proposed excited organic radicals as photoactive species, yet mechanistic studies raised doubts about whether they can truly function as photocatalysts. This skepticism originates from the formation of (photo)redox-active degradation products and the picosecond decay of electronically excited radicals, which is considered too short for diffusion-based photoinduced electron transfer reactions. From this perspective, we analyze important synthetic transformations where organic radicals have been proposed as photocatalysts, comparing their theoretical maximum excited state potentials with the potentials required for the observed photocatalytic reactivity. We summarize mechanistic studies of structurally similar photocatalysts indicating different reaction pathways for some catalytic systems, addressing cases where the proposed radical photocatalysts exceed their theoretical maximum reactivity. Additionally, we perform a kinetic analysis to explain the photoinduced electron transfer observed in excited radicals on subpicosecond time scales. We further rationalize the potential anti-Kasha reactivity from higher excited states with femtosecond lifetimes, highlighting how future photocatalysis advancements could unlock new photochemical pathways.

pubs.acs.org

Total synthesis of (−)-cylindrocyclophane A facilitated by C−H functionalization

(−)-Cylindrocyclophane A is a 22-membered C2-symmetric [7.7]paracyclophane that bears bis-resorcinol functionality and six stereocenters. We report a synthetic strategy for (−)-cylindrocyclophane A th...

science.org

Activation and C−C Coupling of Aryl Iodides via Bismuth Photocatalysis

The catalytic formation of C–C bonds from aryl halides is a highly attractive but unexplored area in the emerging field of bismuth redox catalysis. We report a chemoselective bismuth-photocatalyzed a....

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