ABSTRACT

The structure-activity trends in the imidazolinone series have proven to be fairly restrictive; aside from some changes in substituents on the backbone and some interchangeability of six-membered backbones, alterations led to inactivity. The goal of the work was to increase potency, selectivity, and the spectrum of weeds controlled. This analog approach has generally worked in herbicide research because of the assumption that the initial lead, usually discovered in greenhouse tests, already has satisfied some complex requirements for activity: uptake, translocation, and interference with a vital biological process. This chapter discusses the analog activity which led to the understanding of the moiety responsible for activity. It deals with the structure-activity information concerning inhibition at the enzyme level. A carboxylic acid group, or a group which can be readily transformed to a carboxylic acid, is necessary for activity. Salts of the acid are essentially equivalent to the acids, and this advantage was used in formulations.