Construction of Oxo-Bridged Diazocines via Rhodium-Catalyzed (4+3) Cycloaddition of Carbonyl Ylides with Azoalkenes

Developing
efficient strategies for synthesizing novel diazocine
compounds is valuable because their use has been limited by their
synthetic accessibility. This work describes the catalytic (4+3) cycloaddition
reaction of carbonyl ylides with azoalkenes generated in situ. The rhodium-catalyzed cascade reaction features good atom and step
economy, providing the first access to oxo-bridged diazocines. The
product could be synthesized on a gram scale and converted into diversely
substituted dihydroisobenzofurans.