Abstract
Primary alcohols and phenols have been acetylated with acetylimidazole by the solid state reaction, grinding both substrates with a pestle in a mortar.
Notes
A typical experimental procedure is as follows: A mixture of alcohol 1 and acetylimidazole 2 (1.5∼2 equiv.) was ground well with a pestle in a mortar at room temperature in ambient atmosphere. After manual grinding occasionally at a certain period of time, a mixture of solid began to be wet and melted finally. The reaction was monitored by tlc using a capillary tube keeping ethyl acetate or ethanol inside (usually the reaction completed in 2 hr). The reaction was worked up by dilution with ethyl acetate, and the resulting solution was passed through an SiO2 short column. Evaporation of the solvent left residue which was purified by flash column or medium pressure liquid chromatography to afford the acetate 3
Conventional acetylation using acetic anhydride in pyridine in case of monoacetates 3k, 3l and 3m were failed to give corresponding diacetates. However, monoacetate 3j was obtained in comparable yield