Cooperative Photo-/Lewis Acid Catalyzed Tandem Intramolecular[3 + 2] Cross-Cycloadditions of Cyclopropane 1,1-Diesters with α,β-UnsaturatedCarbonyls for Medium-Sized Carbocycles.

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