Acylation of alcohols and activated aromatic compounds on silica embedded-triflate catalysts

A series of triflate derivatives (La(OTf)(3), tert-butyl-dimethyl-silyltrifluoromethane-sulfonate (BDMST) and triflic acid (HOTf)) embedded in a silica matrix were Used as heterogeneous catalysts for the acylation of alcohols and activated aromatic Compounds. Acylation of saturated alcohols and cyclohexanol resulted in O-acylated products. The acylation of the aromatic compounds was dependent on temperature and substituents. At low temperatures, for phenols and naphtols, acylation occurred mainly to O-acylated. Under these conditions, the presence of catalysts only enhanced the reaction rate. The increase of the temperature above 150 degrees C also led to C-acylation. For anisole and 1-methoxynaphtalene, acylation occurred at the aromatic ring even at low temperatures. (c) 2005 Elsevier B.V. All rights reserved