The p-(methylsulfiiy1) benzyl or Msib ester is recommended as a selectively cleavable carboxyl-protecting group for peptide synthesis. Peptide or amino acid esters of p- (methylsulfiny1) benzyl alcohol, HO-Msib (2), or p-(methy1thio) benzyl alcohol, HO-Mtb (l), are readily prepared from the corresponding alcohols or alkyl halides. Msib esters may also be obtained from Mtb esters by oxidation with m-chloroperbenzoic acid. Msib esters are ...
