A tandem isomerization/intramolecular [3 + 2] cross-cycloaddition (IMCC) of cyclopropane 1,1-diesters with α,β-unsaturated ketones/aldehydes under a cooperative catalysis of photo and Lewis acids has been successfully developed. This supplied a general and efficient strategy for construction of medium-sized carbocyclic (8-, 9-, and 10-membered) skeletons as well as such carbocycle-based bridged oxa-bicyclo[n.2.1] (n = 4-6) skeletons.