Indium Promoted-Convenient Method for Acylation of Alcohols with Acyl Chlorides

Abstract

tions for the acylation of alcohols with acyl chlorides in the presence of indium. The results are summarized in Table 1. Reaction of 2 (1 equiv) with 1 (1 equiv) in the presence of indium (1 equiv) in CH3CN at room temperature produced the corresponding ester in only 21% yield and the starting acyl chloride and alcohol were recovered. The optimal yield of the ester was attained with 3 equiv of 1 or 2 in the presence of 3 equiv of indium. The solvent effect of acylation of 2 with 1 in the presence of indium was studied. The reaction proceeded efficiently in common organic solvents such as DMF, Et2O, THF or CH2Cl2 whereas non-polar solvents such as n-hexane or benzene gave poor yields of the ester. The reactivity of acyl halides was studied. The results are presented in Table 2. The results show that aromatic acyl chlorides with electron-withdrawing groups including the non-substituted led to higher yield than those with electrondonating groups. The acylation of alcohol with aliphatic acyl chlorides also proceeded smoothly affording high yields of the ester. It is noteworthy that carbon-carbon double bonds remained intact under the present reaction conditions while the reaction performed under basic reaction conditions led to a double bond isomerized product. 6