Reaction of O,O-dialkyl alkylphosphonates with thionyl chloride. A remarkable effect of the O-(2-dialkylamino)ethyl substituent

Reaction of dialkyl alkylphosphonates with SOCl₂ in the presence of DMF, reported by Maier, can serve as a convenient route to simple monoalkyl alkylphosphonochloridates. However, when a substrate contains a (2-dialkylamino)ethyl group as one of the ester functions, the course of the reaction is determined by the nature of the N-alkyl groups. With the NMe₂ group present, reaction with SOCl₂ occurs at nitrogen, and no exchange of groups at phosphorus takes place. The NEt₂ group, on the other hand, directs the reaction to phosphorus, and the Maier reaction of the exchange of one ester group OR for Cl proceeds in high yields. © 1996 John Wiley & Sons, Inc.