Dehydroxylative Cross-Electrophile Couplings of 4-Hydroxypyridines with Disulfides for Pyridyl Thioether Synthesis

Abstract An efficient dehydroxylative cross-electrophile coupling of 4-hydroxypyridines with disulfides by employing diphenylphosphine oxide as an activator was developed. The thiolative protocol proceeded effectively via the cleavage of a relatively inert C–OH bond to produce a wide plethora of pyridyl thioethers in moderate to excellent yields. The coupling protocol could also be scaled up with ease and successfully applied to the utilization of diselenide as a substrate. Mechanistic exploration disclosed that in situ-generated S-aryl diphenylphosphinothioate from the reaction of diaryl disulfide with diphenylphosphine oxide presumably functions as the pivotal intermediate of the thioetherification.