(Alkyldithio)carbonyl groups for protection of amino functions in peptide synthesis

(Alkyldithio)carbonyl groups were examined for their usefulness as amino-protecting groups in peptide chemistry. Among the derivatives studied, the (cyclohexyldithio)carbonyl function was found to be the most suitable for practical application. The related amino acid derivatives are obtained by relatively simple procedures and are sufficiently stable under normal conditions of peptide synthesis. Reductive cleavage with thiols or phosphines results in quantitative removal of this new amino protecting group.U