Studies on Peptides. CXXXIV. : Evaluation of S-1-Adamantylcysteine for Peptide Synthesis

Abstract

The S-1-adamantyl (Ad) group of cysteine is more stable to TFA treatment than the S-p-methoxybenzyl (MBzl) group, but is cleavable by 1 M trifluoromethanesulfonic acid-thioanisole in trifluoroacetic acid at 0°C within 60 min or by (CF₃COO)₃ Tl under similar conditions. S-Ad-cysteine is less susceptible to sulfoxide formation than the S-MBzl group. Trimethylphenyl-thiosilane is an effective reducing reagent of the sulfoxide.