Syntheses and lipophilicity measurement of Nα/N-terminus-1,1-dihydroperfluoroalkylated α-amino acids and small peptides

(1,1-Dihydroperfluoroalkyl)phenyliodonium N,N-bis(trifluoromethylsulfonyl)imides (4, n = 0–2) were synthesized and used to transfer the corresponding 1,1-dihydroperfluoroalkyl groups to the α-amino group of (l)tyrosine. The obtained Nα-2,2,2-trifluoroethylated (l)tyrosine (6, n = 0) was further used as the N-terminus in the solid phase peptide synthesis of leucine enkephalin analogue. The lipophilicity of the Nα-1,1-dihydroperfluoroalkylated (l)tyrosines (6, n = 0–2) and N-terminus-2,2,2-trifluoroethylated leucine enkephalin analogue (7), as well as the corresponding parent compounds, was measured.