Boc-S-4-methoxybenzyl-L-cysteine is one of the cysteine derivatives commonly utilized in Boc SPPS. The 4-methoxybenzyl group is removed by HF or TFMSA during cleavage of the peptide from the resin. The cysteine sidechain is released as a free sulfhydryl group. Disulfide bonds can be formed later by a variety of oxidation methods. Boc-S-4-methoxybenzyl-L-cysteine is one of the cysteine derivatives commonly utilized in Boc SPPS. The 4-methoxybenzyl group is removed by HF or TFMSA during cleavage of the peptide from the resin. The cysteine sidechain is released as a free sulfhydryl group. Disulfide bonds can be formed later by a variety of oxidation methods.