Chromium-Catalyzed Radical-Involved Asymmetric Carbonyl Additions

Area of Science:

• Synthetic Organic Chemistry
• Catalysis
• Stereoselective Synthesis

Background:

• Asymmetric carbonyl addition reactions are crucial for synthesizing chiral alcohols.
• Traditional methods using organometallic reagents face challenges with functional group compatibility and constructing vicinal stereocenters.
• Radical reactions offer an alternative with high functional group tolerance but face reactivity and selectivity control issues.

Purpose of the Study:

• To develop a robust platform for radical-based asymmetric carbonyl additions using chromium catalysis.
• To overcome limitations of existing methods for synthesizing chiral molecules with vicinal stereocenters.
• To explore diverse radical precursors and catalytic systems for enantioselective transformations.

Main Methods:

• Utilized chromium catalysis for asymmetric additions to aldehydes and ketones.
• Employed various radical precursors including alkyl halides, imines, alkenes, dienes, enynes, and allenes.
• Investigated metallaphotoredox catalysis and a triple-catalysis system for asymmetric C-H addition.

Main Results:

• Established Cr-catalyzed asymmetric additions using racemic alkyl halides.
• Demonstrated successful asymmetric additions with diverse radical precursors.
• Developed a triple-catalysis system for asymmetric α-C-H addition to produce β-amino alcohols.

Conclusions:

• Chromium-catalyzed asymmetric carbonyl additions provide efficient pathways to chiral molecules with vicinal stereocenters.
• Mechanistic studies revealed distinct transition state models, differing from Ni- or Cu-catalyzed reactions.
• This work expands the scope of enantioselective radical chemistry and stimulates further research in the field.