Electrogenerated magnesium-associated cyanomethyl anions/bases obtained from the electrochemical reduction of acetonitrile and the oxidation of a sacrificial magnesium rod were successfully used to promote the addition of carbon disulfide to primary benzylic amines. Alkylation with ethyl 3-bromopropionate acid ester or with ethyl 2-bromoacetate acid ester yields the corresponding ring-opened carbamodithioate