Photochemical Reaction of Vinyldiazo Esters and Azides: Synthesis of β-Oxodiazo Compounds.

A photochemical diazo transfer strategy has been developed for the synthesis of unusual β-oxodiazo compounds. Vinyldiazo esters generate transient cyclopropene-1-carboxylates upon selective photolysis, which undergo 1,3-dipolar cycloaddition with TMSN3 followed by a retro-1,3-dipolar process to deliver β-diazoimines. Hydrolysis of these intermediates affords a broad range of β-diazoaldehydes and β-diazoketones. The synthetic potential of this underexplored diazo class is further highlighted through diverse transformations of both the carbonyl and diazo functionalities.