Tetrahydropyranyl protection and deprotection of alcohols using a niobium-based Bronsted acid catalyst

Solid niobium oxide treated with phosphoric acid (NbP) was used as a heterogeneous catalyst in the protection of a series of aliphatic alcohols as tetrahydropyranyl (THP) derivatives. Protection of primary alcohols using this material with strong Bronsted acid sites was achieved in good yields (75%-94%), while moderate values were obtained in the protection of secondary and tertiary alcohols (50%-84%), largely dependent on the steric hindrance in the proximity of the hydroxyl moiety. NbP also catalyzed deprotection of THP ethers derived from primary alcohols and phenol with moderate yields (65%-99%).