A General Strategy for Aliphatic C-H Functionalization Enabled by Organic Photoredox Catalysis

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Functionalizing unactivated aliphatic C-H bonds is challenging but crucial for molecule synthesis.
• Intermolecular C-H functionalization offers versatile routes for complex molecule construction and late-stage modification.

Purpose of the Study:

• To develop a general and efficient method for intermolecular functionalization of aliphatic C-H bonds.
• To demonstrate a broad scope of C-H transformations using a photoredox catalytic system.

Main Methods:

• Utilized an acridinium photoredox catalyst and a phosphate salt.
• Employed blue light-emitting diode (LED) irradiation for the reactions.
• Investigated mechanistic pathways through detailed studies.

Main Results:

• Achieved direct conversion of C-H bonds to C-N, C-F, C-Br, C-Cl, C-S, and C-C bonds.
• Demonstrated the strategy's effectiveness with alkane substrates as the limiting reagent.
• Identified a putative oxygen-centered radical as the key hydrogen atom-abstracting species.

Conclusions:

• The developed photoredox catalytic system provides a general approach for intermolecular C-H functionalization.
• This methodology expands the toolkit for synthesizing and derivatizing complex organic molecules.
• Mechanistic insights suggest a novel radical-mediated pathway for C-H activation.