Facile Pyridine S N Ar Reactions via N-Phosphonium–Pyridinium Intermediates

Here we report that N-phosphonium pyridinium intermediates are unusually reactive for pyridine SNAr reactions. Specifically, forming phosphonium salts from halopyridines typically requires elevated temperatures and Lewis acid additives. The alternative activation mode described in this paper enables C–P bond formation to occur at ambient temperatures in many cases and functions across a broad range of substrates.