1967, Vol.40, No.9
The properties of anhydrous hydrogen fluoride (HF) as a reagent for the acidolysis of various protective groups have been studied. Amino acids with various protective groups were each treated with HF at 0 or 20°C in the presence of anisole, and the reaction products were tested. Thus, HF was found to be much better than the other known reagents, such as hydrogen bromide and trifluoroacetic acid. In the present study, the following groups were shown, for the first time, to be removed safely: the nitro group in nitroarginine, the diphenylmethyl group in diphenylmethylamide, the t-butyl group in S-t-butylcysteine, the isopropyloxycarbonyl group, and the isopropyl ester group. A new and convenient apparatus was designed for the safe handling of HF for peptide synthesis.