Photochemically Induced Aryl Azide Rearrangement: Solution NMR Spectroscopic Identification of the Rearrangement...

Area of Science:

• Organic Photochemistry
• Fluorinated Organic Compounds
• Spirocyclic Chemistry

Background:

• Azidobenzoate derivatives are versatile synthetic precursors.
• Photochemical reactions offer unique pathways for complex molecule synthesis.
• Regioselective synthesis is crucial for developing targeted chemical entities.

Purpose of the Study:

• To investigate the photochemical behavior of ethyl 3-azido-4,6-difluorobenzoate.
• To elucidate the reaction mechanism leading to spirocyclic product formation.
• To characterize the structure of the photoproduct using advanced spectroscopic and computational methods.

Main Methods:

• Photolysis of ethyl 3-azido-4,6-difluorobenzoate in the presence of oxygen.
• Regioselective synthesis of the target spirocyclic compound.
• Structure elucidation using multinuclear solution Nuclear Magnetic Resonance (NMR) spectroscopy.
• Density Functional Theory (DFT) calculations to support mechanistic and structural findings.

Main Results:

• The photolysis reaction regioselectively yielded ethyl 5,7-difluoro-4-azaspiro[2.4]hepta-1,4,6-triene-1-carboxylate.
• A ketenimine intermediate was proposed, undergoing photochemical electrocyclization and rearrangement.
• NMR spectroscopy and DFT calculations confirmed the structure of the photorearrangement product.

Conclusions:

• The study demonstrates a novel photochemical route to a difluorinated azaspirocyclic compound.
• The findings highlight the utility of photochemistry in constructing complex heterocyclic scaffolds.
• The combination of experimental spectroscopy and theoretical calculations provides robust structural and mechanistic insights.