Ring-Contraction Reaction of Substituted Tetrahydropyrans via Dehydrogenative Dual Functionalization by Nitrite-Catalyzed Double Activation of Bromine.

A nitrite-catalyzed ring contraction reaction of substituted tetrahydrofurans by oxidation of bromide under aerobic conditions as a dehydrogenative dual functionalization was developed to provide 2-acyltetrahydrofurans in good yields. On the other hand, the oxidation reaction of 1-substituted isochromans occurred via the bromohydroxylation to give 1-(dibromoalkyl)-1-hydroxyisochromans in high yields.