Sulphonamidomercuriation of olefins and subsequent reductive demercuriation or bromodemercuriation

Abstract

The addition of toluene-p-sulphonamide to olefins in the presence of anhydrous mercury(II) nitrate and subsequent sodium borohydride reduction leads to the corresponding N-alkylsulphonamides. The sulphonamidomercuriation–demercuriation of 1,4- and 1,5-dienes yields saturated nitrogen-containing heterocycles. A possible mechanism for the stereoselective synthesis of cis-2,5-dimethyl-N-tosylpyrrolidine is proposed. The treatment of the intermediate organomercurials, isolated as the sodium salts of their bromomercurio derivatives, with bromine gives the corresponding 2-bromoalkyl-sulphonamides through a regiospecific bromodemercuriation process.