Tmob Side Chain‐protected S‐Cysteine‐ and homo‐S‐Cysteinesulfonamides, their Nα‐Protected and Nω‐Aminoethylated Derivatives

The 2,4,6-trimethoxybenzyl (Tmob) group is very suitable for temporary protection of the aminosulfonyl group of S-cysteine- and homo-S-cysteinesulfonamides. Both the introduction and removal of the Tmob-protecting group can be achieved in high yields. 2-Aminoethyl derivatization of the aminosulfonyl group of S-cysteine- and homo-S-cysteinesulfonamides has been carried out, and various derivatives useful for peptide synthesis with Z, Boc and Fmoc as Nα-protecting groups have been prepared. In all cases, a racemic mixture of S-cysteine- or homo-S-cysteinesulfonic acid has been used and subsequent enantiomer resolution has been achieved by treatment with Bacillus subtilis alkaline protease.