A Novel Synthesis of Oxabicyclo[3.3.1]nonanone via (3,5)-Oxonium−Ene Reaction

Oxabicyclo[3.3.1]nonanone can conveniently be prepared by the reaction of trans-p-menth-6-ene-2,8-diol and aldehyde or epoxide mediated by boron trifluoride etherate in good yields. The reaction proceeds via (3,5)-oxonium−ene-type reaction.