Dimethyl(methylthio)sulfonium tetrafluoroborate: A reagent for disulfide bond formation in peptides

Dimethyl(methylthio)sulfonium tetrafluoroborate (1) has been used to deprotect a series of cysteine derivatives (BocCys-Acm, MeOBzl, Trt) with concurrent disulfide bond formation. This reagent has also been applied to the deprotection and disulfide bond formation in two peptides: a sarafotoxin A fragment and an analog of calcitonin where each peptide contains two S-protected cysteine derivatives: [Cys(Acm)]