Solvent-free tetrahydropyranylation (THP) of alcohols and phenols and their regeneration by catalytic aluminum chloride hexahydrate

A catalytic amount of aluminum chloride hexahydrate enables solvent-free tetrahydropyranylation (THP) of alcohols and phenols at moderate temperatures. A simple addition of methanol helps to regenerate the corresponding alcohols and phenols, thus rendering these protection and deprotection sequences as very efficient transformations at high substrate to catalyst ratios.