SYNTHESIS AND HERBICIDAL ACTIVITY OF PHENYLPROPARGINOLS

A three-step/one-pot procedure was developed for preparing herbicidal fluorophenylproparginols from acetophenones by way of an enol phosphat e intermediate. Side-by-side testing of 16 of the more active analogs showed that oxy-2,3,5,6-tetrafluorophenyl)ethynyl]cyclohexanol (21c) w as the most potent example. On the basis of the biological response da ta obtained for these first-tier analogs, a physiochemical ''structura l space'' was defined. Twenty additional analogs were then targeted fo r synthesis in an experimental design set up to probe that structural space. Scaled rank sums analysis of herbicidal activity for these seco nd-tier analogs produced a quantitative structure/activity relationshi p model indicating that 21c bears a substitution pattern that is at or near the optimum for this class of chemistry.