Access to N-Alkylazaheterocyclic Salts by Activation of Alkoxy C–O Bonds in Polyol Esters

A wide variety of N-alkylazaheterocyclic salts are conveniently synthesized from polyol esters and azaheterocyclic salts under solventless conditions. In particular, paraquat-like derivatives showed comparable herbicidal activity toward several common weeds. Mechanistic studies suggest that polyesters likely underwent partial hydrolysis and neighboring group participating dehydration under the action of acidic salt to generate five-membered ring intermediates, which reacted with the azaheterocycle to accomplish the N-alkylation.