A facile route to 3,7-cis-disubstituted cycloocta-1,5-diene-1,2,5,6- tetracarboxylates through photochemical [2 + 2]cycloaddition of 3-substituted cyclobutene-1,2-dicarboxylates and thermal isomerization†

Photochemical dimerization of 3-substituted cyclobutene-1,2-dicarboxylates followed by thermal isomerization gives regio- and stereo-selectively 3,7-cis-disubstituted cycloocta-1,5-diene-1,2,5,6-tetracarboxylates.