Synthesis and properties of 4,9-methanoundecafulvenes and their transformation to 3-substituted 7,12-methanocycloundeca[4,5]furo[2,3-d]pyrimidine-2,4(1H,3H)-diones: photo-induced autorecycling oxidizing reaction toward amines

The synthesis and properties of 4,9-methanoundecafulvene [5-(4,9-methanocycloundeca-2′,4′,6′,8′,10′-pentaenylidene)pyrimidine-2,4,6(1,3,5H)-trione] derivatives were studied. Their structural characteristics were investigated on the basis of the 1H and 13C NMR and UV–vis spectra. The rotational barrier (ΔG‡) around the exocyclic double bond of was found to be 12.55 kcal mol−1 by the variable temperature 1H NMR measurement. The electrochemical properties of were also studied by CV measurement. Furthermore, the transformation of to 3-substituted 7,12-methanocycloundeca[4,5]furo[2,3-d]pyrimidine-2,4(1H,3H)-diones was accomplished by oxidative cyclization using DDQ and subsequent ring-opening and ring-closure. The structural details and chemical properties of were clarified. Reaction of with deuteride afforded C13-adduct as the single product, and thus, the methano-bridge controls the nucleophilic attack to prefer endo-selectivity. The photo-induced oxidation reaction of and a vinylogous compound, 3-methylcyclohepta[4,5]furo[2,3-d]pyrimidine-2,4(3H)-dione , toward some amines under aerobic conditions were carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) with the recycling number of 6.1–64.0 (for ) and 2.7–17.2 (for ), respectively.