Oxygenation via C-H/C-C Bond Activation with Molecular Oxygen

Area of Science:

• Organic Chemistry
• Catalysis
• Green Chemistry

Background:

• Selective oxidation of organic molecules is crucial in synthetic chemistry.
• Direct oxidative C-H and C-C bond functionalization offers efficient synthesis routes.
• Molecular oxygen is an ideal, sustainable oxidant due to its atom economy and environmental friendliness.

Purpose of the Study:

• To develop novel protocols for oxygenation using molecular oxygen as the oxidant and oxygen source.
• To synthesize O-containing compounds through C-H, C-C, C═C, and C≡C bond activation.
• To explore transition-metal, organocatalyst, and photocatalyst-mediated aerobic oxidation and oxygenation reactions.

Main Methods:

• Utilized transition-metal catalysis, organocatalysis, and photocatalysis for aerobic oxidation and oxygenation.
• Employed molecular oxygen (O2) or air under 1 atm pressure.
• Investigated cyclization reactions for O-heterocycle construction.
• Conducted mechanistic studies including isotope labeling and electron paramagnetic resonance (EPR) spectroscopy.

Main Results:

• Successfully incorporated one or two oxygen atoms into various substrates via C-H, C-C, C═C, and C≡C bond cleavage.
• Developed efficient cyclization reactions for synthesizing O-heterocycles.
• Demonstrated broad functional group tolerance in the developed transformations.
• Identified single electron transfer processes involving radical intermediates in the reaction mechanisms.
• Synthesized a wide range of O-containing compounds, including α-keto amides, esters, ketones, aldehydes, phenols, and O-heterocycles.

Conclusions:

• The developed aerobic oxidation and oxygenation protocols offer green and efficient synthetic routes to valuable O-containing compounds.
• Inexpensive and low-toxicity catalysts like Cu, Fe, Mn, or NHPI are effective for these transformations.
• The high efficiency, atom economy, and practicality of these methods make them attractive for synthetic applications.