O → S Relay Deprotection: A General Approach to Controllable Donors of Reactive Sulfur Species

Reactive sulfur species (RSS) are biologically important molecules. Among them, H2S, hydrogen polysulfides (H2Sn, n > 1), persulfides (RSSH), and HSNO are believed to play regulatory roles in sulfur-related redox biology. However, these molecules are unstable and difficult to handle. Having access to their reliable and controllable precursors (or donors) is the prerequisite for the study of these sulfur species. Reported in this work is the preparation and evaluation of a series of O-silyl-mercaptan-based sulfur-containing molecules which undergo pH-or F--mediated desilylation to release the corresponding H2S, H2Sn, RSSH, and HSNO in a controlled fashion. This O -> S relay deprotection serves as a general strategy for the design of pH-or F--triggered RSS donors. Moreover, we have demonstrated that the O-silyl groups in the donors could be changed into other protecting groups like esters. This work should allow the development of RSS donors with other activation mechanisms (such as esterase-activated donors).