Abstract Pyridinium perchlorate is an effective catalyst for the reaction of trialkyl phosphites with various C= X electrophiles: aldehydes, ketones, ketophosphonates, imines, isocyanates, isothiocyanates, and activated alkenes. The reaction leads to the formation of α- substituted phosphonates in a high yield. Advantages of the new catalyst are its high activity, availability, high product yields, and mild reaction conditions.
