Efficient Tetrahydropyranylation of Phenols and Alcohols Catalyzed by Supported Mo and W Keggin Heteropolyacids

Abstract

The protection of phenols as tetrahydropyranyl acetals is studied using supported Keggin heteropolyacids as catalysts, specifically molybdophosphoric or tungstophosphoric acids supported on silica. Phenol tetrahydropyranyl acetals are obtained in short times at room temperature with excellent yields. Protection of alcohols is also performed under mild conditions using both supported heteropolyacids, with yields ranging between good and quantitative. The reactions are clean and their workup is very simple. The use of these solid catalysts allows replacing the usual soluble inorganic acids, contributing to waste reduction.

Keywords:

• Protecting group
• Tetrahydropyranyl
• Heteropoly-acids
• Keggin catalyst
• Alcohols
• Phenols

Acknowledgments

Financial support of Universidad Nacional de La Plata, CONICET and Agencia Nacional de Promoción Científica y Tecnológica (Argentina) is gratefully acknowledged.