Selective, one‐pot synthesis of 2,3,6‐trisubstituted pyridine and 2‐cyclohexen‐1‐one derivatives from bicyclic ketals

Boron difluoromethanesulfonate, prepared from 5 equivalents of trimethylsilyl methanesulfonate and 1 equivalent of boron trifluoride etherate, has proved to be an active Lewis acid catalyst for the one‐pot transformation reaction of bicyclic ketals in the 6,8‐dioxabicyclo[3.2.1]octane series to 2,3,6‐trisubstituted pyridine or 2‐cyclohexen‐1‐one selectively, depending on conditions. A 1,5‐diketone was the reaction intermediate for both products. Pyridine was formed selectively by using a nitrile as a solvent or a reagent, but cyclohexenone was prepared in methylene chloride instead of a nitrile.