Aldehydes and ketones caged as 4-(2,5-dihydroxyphenyl)-1,3-dioxolanes are efficiently (Phi = 0.1-0.2) released in a good to excellent chemical yield upon irradiation with 300 nm light. Caged carbonyl compounds are prepared by their acetalization with (2,5-dimethoxyphenyl)ethylene glycol followed by oxidative demethylation to produce corresponding (1,3-dioxolane-4-yl)-1,4-benzoquinones. The latter acetals are photochemically inert but can be converted into photolabile hydroquinones by mild reduction in situ.