Tandem SN2-Michael Reactions for the Preparation of Simple Five- and Six-Membered-Ring Nitrogen and Sulfur Heterocycles

Article abstract of DOI:10.1021/jo00032a025

A one-pot tandem SN2-Michael addition sequence has been developed for the preparation of five-membered- and six-membered-ring nitrogen and sulfur heterocycles from 6- or 7-halo-2-alkenoate esters.Nitrogen-containing rings are prepared by reaction of the ω-halo-2-alkenoate ester with a primary amine in the presence of triethylamine.The sulfur analogues are generated by thiourea displacement of the halide followed by base hydrolysis of the isothiouronium salt.Yields are routinely in the 60-80percent range.Experiments are described which elucidate the chronology of the reaction sequences.Ring size and steric hindrance to the initial substitution reaction appear to be the only limitations of the procedure.