Application and details of photoinduced oxidative cyclization of 5-(4′,9′-methanocycloundeca-2′,4′,6′,8′,10′-pentaenylidene)pyrimidine-2,4,6(1,3,5H)-triones and related compounds

摘要: Abstract As novel methodology for synthesizing the furan ring, a photoinduced oxidative cyclization of 5-(4′,9′-methanocycloundeca-2′,4′,6′,8′,10′-pentaenylidene)pyrimidine-2,4,6(1,3,5H)-triones (7a–c) and related compounds 9a–c was accomplished to give 5,10-methanocycloundeca[4,5]furo[2,3-d]pyrimidine-2,4(1,3H)-dionylium tetrafluoroborates (8a–c+·BF4−) 2a–c+·BF4−, respectively. In cyclization, molecular oxygen in air is used as oxidant reaction proceeds under mild conditions desired products without byproducts, thus, it interesting from viewpoint green chemistry. On reactions mono-substituted derivatives 7d,e 9e,f, selectivity cyclizations were reversed compared with those DDQ-promoted cyclizations. By NMR monitoring 7a deuterated compound 7a-D2 degassed conditions, details pathway clarified rationalized on basis MO calculation by 6-31G∗ set MP2 levels well.