Abstract
The photoisomerization of the Diels–Alder adduct formed between tetramethylpurpurogallin and maleic anhydride is described. The process is highly stereoselective, involves the β,γ-unsaturated ketone chromophore present in the adduct, proceeds through the formation of allyl and aroyl radical intermediates, and leads to a novel substituted dihydrofluorenone in good yields.
ACKNOWLEDGMENTS
Financial support from the Agencia Nacional de Investigación e Innovación, the Comision Sectorial de Investigación Científica, the National Science Foundation, and the Royal Society of Chemistry is acknowledged. We also thank Alexander Khrizman for technical support.