N-Alkyl thiocarbamoyl phosphonic acid esters—2 : Alkylation by methyl iodide accompanied by phosphonate dealkylation

Thiocarbamoyl phosphonates 1 did not react with alkylating agents to give the S-alkyl derivatives 2, but gave zwitterions 3a–e in which the phosphonate ester moiety was dealkylated. In some starting material could be recovered. A mechanism is suggested in order to explain the relationship between the alkylation and the dealkylation steps of the reaction.