Flexible Synthesis and Herbicidal Activity of Fully Substituted 3‐Hydroxypyrazoles

Abstract

AbstractThe synthesis and herbicidal efficacy of a novel library of fully substituted 3‐hydroxypyrazoles is reported. An efficient, divergent approach to introduce phenyl, phenoxy, phenylsulfanyl, anilino and benzyl substituents in the 4‐position of the pyrazole, alongside a flexible synthesis of N1‐alkyl analogues is described via final step diversification of key intermediates. Herbicidal screening of the prepared compounds against key weed species identified the lead compound 2‐[4‐(2,4‐difluorophenoxy)‐1,5‐dimethyl‐pyrazol‐3‐yl]oxy‐5‐fluoropyrimidine, which was prepared on a multi‐gram scale using an optimised synthetic route.