Regioselective substitution of phenols with trifluoroacetaldehyde ethyl hemiacetal

Phenol did not react directly with trifluoroacetaldehyde ethyl hemiacetal. In the presence of catalytic amounts of anhydrous potassium carbonate, howe ver, the reaction readily occurred. The p-substituted product 4-(2,2,2-trif luoro-1-hydroxyethyl)phenol predominated. In contrast, the reaction catalyz ed by zinc halide predominantly produced the o-substituted product. Corresp onding reactions of several phenols were studied under the same catalytic c onditions.