Synthesis of 3,4-disubstituted furans via unsaturated cyclic peroxides arising by photooxygenation of 2,3-bis (bromomethyl)-1,3-butadiene and derived exocyclic dienes

The reaction of 2,3-bis (bromomethyl)-1,3-butadiene (3) with singlet oxygen resulted in the formation of a peroxide (4) which rearanged with CoTPP to bis(bromomethyl)furan. Zinc-induced debromination of cycloadducts which were obtained from the [2+4] Diels-Alder reactions of 3 with DMAD and benzyne gave exocyclic dienes 7 and 11 from which fused ring furans were prepared by photooxygenation followed by rearrangement. 4,5-Dimethylene-1,2-dioxane (14) was synthesized by zinc-induced debromination of 4. The cycloaddition reactions of 14 with MTAD, singlet oxygen and DMAD were studied. (C) 1997 Elsevier Science Ltd.