Photosolvolysis Reactions of 3-Alkoxypyridinium Tetrafluoroborate Salts.

Irradiation of a series of 3-alkoxypyridinium tetrafluoroborate salts in alcohol solution resulted in the formation of cyclopentenone ketals by diastereoselective incorporation of the alcohol solvent under the basic conditions of the photolysis reaction. In a second series of photochemical reactions, the same 3-alkoxypyridinium salts were irradiated in water to yield β-hydroxycyclopentanones stereoselectively.