Versatile and stereloselective syntheses of orthogonally protected β-methylcysteine and β-methyllanthionine

Lantibiotics are a class of lanthionine (and/or beta-methyllanthionine)-containing peptides with antibioitic activity against Gram-positive bacteria. As part of our research effort directed toward the synthesis and mechanistic study of the lantibiotic peptide mersacidin (1), we report stereoselective syntheses of orthogonally protected beta-methylcysteine (beta-MeCys) and,beta-methyllanthionine (beta-MeLan), two key nonnatural amino acid components of the mersacidin architecture.