Easy Preparation of Bioactive Peptides from the Novel Nα-Trifluoroethyl Amino Acids

Nα-Trifluoroethyl amino acids have been prepared for the first time and unexpectedly found to behave as conventionally N-protected amino acids. Novel unnatural peptides are easily prepared in high yields without racemization. The observed chemistry results from steric factors as well as from the acidity of the CF3CH2NH group, according to comparative experiments. Of ten dipeptides that were tested for antitumor activity, CF3CH2–L-Tyr–L-Ile–OtBu was the most active.