The only cyclic α-diazocarbonyl compound employed in the Büchner-Curtius-Schlotterbeck ring expansion of cyclic ketones to date was α-diazo-γ-butyrolactone. Encouraged by the recent success using α-diazo acetamides in related Tiffeneau-Demjanov type ring expansions, we extended this approach to various α-diazo-γ-butyrolactams, which produced, under BF₃ ·OEt₂ -promoted conditions, spirocyclic seven-membered ketones. These findings substantially enhance the possibilities offered by cyclic α-diazocarbonyl compounds in constructing privileged spirocyclic scaffolds for drug design.