in N-methyl-acetamide; diethyl ether; hexane; mineral oil

in N-methyl-acetamide; water; N,N-dimethyl-formamide

4 A molecular sieve; toluene-4-sulfonic acid in toluene; Petroleum ether 24 h; Heating;

1: 43 percent / trifluoroacetic acid, water / CH2Cl2 / Ambient temperature 2: 49 percent / p-toluenesulfonic acid monohydrate, molecular sieves type 4A / light petroleum; toluene / 24 h / Heating View Scheme