Realizing an Aza Paternò-Büchi Reaction

Area of Science:

• Organic Chemistry
• Photochemistry
• Asymmetric Synthesis

Background:

• The Paternò–Büchi reaction is a photochemical reaction forming oxetanes from alkenes and carbonyl compounds.
• Aza Paternò–Büchi reactions extend this to imines, forming azetidines.
• Atropisomeric compounds possess axial chirality, offering unique stereochemical control.

Purpose of the Study:

• To develop an intramolecular atropselective aza Paternò–Büchi reaction.
• To synthesize azetidine products with high enantioselectivity.
• To elucidate the reaction mechanism and enamide reactivity.

Main Methods:

• Sensitized photoirradiation of atropisomeric enamide and imine substrates.
• Detailed photophysical studies.
• Isomerization kinetic studies.

Main Results:

• Successful synthesis of azetidine products via intramolecular aza Paternò–Büchi reaction.
• Achieved high yields and excellent enantioselectivity (ee >96%).
• Developed a mechanistic model explaining enamide reactivity in this transformation.

Conclusions:

• The developed method provides efficient access to enantiomerically enriched azetidines.
• The study offers insights into the mechanism of photochemical reactions involving enamides.
• This work expands the scope of asymmetric photochemical synthesis.