A New Synthesis of N-substituted Imidobissulfates from Amidosulfates

Abstract

In order to develop a general synthetic route to N-substituted imidobissulfates, the reaction of di-n-butyl-ammonium methylamidosulfate with a variety of sulfonating agents was investigated.The sulfonating agents used in this study were sulfur trioxide as well as a number of sulfur trioxide complexes with Lewis bases, i. e. 1, 4-dioxane, N, N-dimethylformamide, pyridine, 2-picoline, 2, 6-lutidine, trimethylamine, and triethylamine.Sulfonation of the methylamidosulfate with the tertiary amine-sulfur trioxide complexes gave directly methylimidobissulfate in excellent yields (90%). On the other hand, the use of sulfur trioxide as well as sulfur trioxide complex with 1, 4-dioxane or N, N-dimethylformamide led to “methylamidodisulfate”, which afforded, on treatment with an appropriate base such as triethylamine, methylimidobissulfate in varying yields (1860%) depending upon the time of treatment. Mechanisms of the reaction are discussed.Ten N-substituted imidobissulfates, of which five are new compounds, were synthesized in 6490% yields by N-sulfonation of the corresponding amidosulfates with 2-picoline-sulfur trioxide in 2-picoline as solvent at room temperature, and their infrared spectral data are also described.This new reaction provides a general, high-yield method for the preparation of N-substituted imidobissulfates, especially the secondary alkyl as well as cycloalkyl derivatives inaccessible by previously reported methods.