A Pyridinium Ylide-Alkylation Strategy for the Structural Diversification of N-Carbamoylpyridinium Salts

A pyridinium ylide-alkylation strategy has been developed for selectively accessing N,N-disubstituted pyridinium salts from monosubstituted pyridinium salts possessing ambident nucleophiles. The method was shown to be tolerant toward an array of different pyridinium scaffolds and common electrophiles, enabling access to structurally diverse pyridinium salts. The potential versatility of the approach was demonstrated through the synthesis of chemically complex, heterotrifunctional pyridinium salts containing a pyridinium warhead, a click chemistry handle, and a third, high-value, payload.