Efficient Entry into Medium-Ring Keto-Lactones. The Ruthenium Tetraoxide-Promoted Oxidative Cleavage of β-Hydroxyethers

A new use of ruthenium tetraoxide is reported. The catalytic oxidative cleavage of hexahydro-benzofuran-3a-ols led to nine-membered ring keto-lactones in moderate to good yields and high purity. The reaction is clean and easily performed using catalytic amounts of ruthenium trichloride and an excess of sodium periodate as a cooxidant.