A number of 1-alkyl-1,3,2-diazaphospholidin-4-thione-2-sulfides(2) have been synthesized by the cyclization reaction of Lawesson's reagent with 3- alkyl- glycinamides(1). The bio-assay indicates that some of compounds prepared have good selective herbicidal activity and the quantitative structure- herbicidal activity relationship (QSAR...