Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Using acetyl hypoflurite a regiospecific electrophilic fluorination of the tyrosine ring of the N-terminal tetrapeptide amide (Tyr-D-Ala-Phe-Gly-NH 2 ) sequence of the opiate peptide dermorphin has been achieved in good yields. ... J. Med. Chem., 30 (1987), p. 1538 and references therein.