Preyssler heteropolyacid H 14[NaP 5W 29MoO 110]: A heterogeneous, green and recyclable catalyst used for the protection of functional groups in organic synthesis

Abstract

Efficient protection of alcohols, phenols, amines, thiols and aldehydes has been carried out under catalysis by the highly active Preyssler heteropolyacid H 14[NaP 5W 29MoO 110] (H 14PMo). In this paper we report the catalytic activity of bulk H 14PMo in each procedure to form: 2-tetrahydropyranyl acetals of alcohols and phenols, working at room temperature and using toluene as solvent; aldehyde 1,1-diacetates (acylals), a solvent-free preparation using Ac 2O at room temperature; alcohol acetates, phenols, amines and thiols, working at room temperature, using toluene as solvent and Ac 2O as acetylating agent; benzhydryl-ethers from the reaction of alcohols or phenols and diphenylmethanol, in toluene at 60–80 °C; and silylation of phenol and alcohols with hexamethyldisilazane as silylating agent in toluene at 85 °C. All the described procedures provide useful alternatives for performing the protection of different functional groups, which are general, rapid, selective and inexpensive, and have a low environmental impact. The catalyst was easily recovered and reusable in all of the described procedures, without loss of its catalytic activity.