NHC-Catalyzed Access to Benzoxazepinones via Aromatization-Driven Rearrangement

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Heterocyclic Chemistry

Background:

• Benzazepine derivatives, including benzoxazepines, are important nitrogen-containing heterocycles in pharmaceuticals.
• Efficient synthesis of complex heterocyclic frameworks remains a key challenge in drug discovery.

Purpose of the Study:

• To develop a novel carbene-catalyzed strategy for constructing oxazepine derivatives.
• To explore aza-spirocyclization followed by aromatization-driven rearrangement for synthesizing benzo-fused seven-membered heterocycles.

Main Methods:

• Carbene catalysis was employed for the reaction between β-methyl enals and 5-enepyrrolin-4-ones.
• The reaction proceeds via a spirocyclic pyrrolidone intermediate.
• Oxidative conditions were used to achieve the final aromatization-driven rearrangement.

Main Results:

• The study successfully synthesized diverse oxazepine derivatives.
• The method provides rapid access to benzo-fused seven-membered heterocyclic products.
• A key spirocyclic pyrrolidone intermediate was identified.

Conclusions:

• The developed carbene-catalyzed strategy offers an efficient route to structurally diverse oxazepines.
• This method highlights the synthetic utility of N-heterocyclic carbene (NHC) catalysis in complex heterocycle construction.
• The synthesized oxazepines can be further functionalized, demonstrating their potential in medicinal chemistry.