Vacuum flash pyrolysis (VFP) of malonyl peroxides: decarboxylation versus decarbonylation of the intermediary α-lactones

Vacuum Flash Pyrolysis (VFP) at ca. 450–500°C and ca. 0.1–0.3 Torr of the spirocyclic malonyl peroxides ($\text{2a,b}$) affords high yields of allenes ($\text{5a,b}$), while the simple malonyl peroxide ($\text{2c}$) leads to ketone ($\text{4}$), derived respectively from decarboxylation and decarbonylation of the intermediary α-lactones ($\text{3}$).