Dipolar cyclization reactions in heterocyclic synthesis: A novel route to furanophanes

Article abstract of DOI:10.1016/S0040-4039(00)77672-6

The multistep transformation of 2,3-bridged butenynyl oxiranes 8 into furanophanes 12 involving bridgehead olefins 11 as key intermediates is described. The two lower members of 12 undergo rapid air oxidation resulting in the formation of the dienediones 14a,b. 14b is converted by base into the bicyclo[6.3.0]undecadienone 15.