The
merger of photoredox catalysis with transition metal catalysis,
termed metallaphotoredox catalysis, has become a mainstay in synthetic
methodology over the past decade. Metallaphotoredox catalysis has
combined the unparalleled capacity of transition metal catalysis for
bond formation with the broad utility of photoinduced electron- and
energy-transfer processes. Photocatalytic substrate activation has
allowed the engagement of simple starting materials in metal-mediated
bond-forming processes. Moreover, electron or energy transfer directly
with key organometallic intermediates has provided novel activation
modes entirely complementary to traditional catalytic platforms. This
Review details and contextualizes the advancements in molecule construction
brought forth by metallaphotocatalysis.
Fluorinated organic molecules are pervasive within the pharmaceutical and agrochemical industries due to the range of structural and physicochemical properties that fluorine imparts. Currently, the most abundant methods for the synthesis of the aryl-CF 2 functionality have relied on the deoxyfluorination of ketones and aldehydes using expensive and poorly atom economical reagents. Here, we report a general method for the synthesis of aryl-CF 2 R and aryl-CF 2 H compounds through activation of the corresponding trifluoromethyl arene precursors. This strategy is enabled by an endergonic electron transfer event that provides access to arene radical anions that lie outside of the catalyst reduction potential. Fragmentation of these reactive intermediates delivers difluorobenzylic radicals that can be intercepted by abundant alkene feedstocks or a hydrogen atom to provide a diverse array of difluoalkylaromatics.
A mild, modular, and practical catalytic system for the synthesis of the highly privileged phenethylamine pharmacophore is reported. Using a unique combination of organic catalysts to promote the transfer of electrons and hydrogen atoms, this system performs direct hydroarylation of vinyl amine derivatives with a wide range of aryl halides (including aryl chlorides). This general and highly chemoselective protocol delivers a broad range of arylethylamine products with complete regiocontrol. The utility of this process is highlighted by its scalability and the modular synthesis of an array of bioactive small molecules.
We report the photoredox alkylation of halopyridines using functionalized alkene and alkyne building blocks. Selective single-electron reduction of the halogenated pyridines provides the corresponding heteroaryl radicals, which undergo anti-Markovnikov addition to the alkene substrates. The system is shown to be mild and tolerant of a variety of alkene and alkyne subtypes. A combination of computational and experimental studies support a mechanism involving proton-coupled electron transfer followed by medium-dependent alkene addition and rapid hydrogen atom transfer mediated by a polarity-reversal catalyst.
Modern proximity labeling techniques
have enabled significant advances
in understanding biomolecular interactions. However, current tools
primarily utilize activation modes that are incompatible with complex
biological environments, limiting our ability to interrogate cell-
and tissue-level microenvironments in animal models. Here, we report
μMap-Red, a proximity labeling platform that uses a red-light-excited
SnIV chlorin e6 catalyst to activate a phenyl azide biotin
probe. We validate μMap-Red by demonstrating photonically controlled
protein labeling in vitro through several layers
of tissue, and we then apply our platform in cellulo to label EGFR microenvironments and validate performance
with STED microscopy and quantitative proteomics. Finally, to demonstrate
labeling in a complex biological sample, we deploy μMap-Red
in whole mouse blood to profile erythrocyte cell-surface proteins.
This work represents a significant methodological advance toward light-based
proximity labeling in complex tissue environments and animal models.
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