Pyrimidinyl Carboxylates and Sulfonanilides

The pyrimidinyl salicylates (PSs) constitute a class of acetolactate synthase (ALS)-inhibiting herbicides that was discovered during the 1990s. The representatives of this chemical class are bispyribac-sodium and pyriminobac-methyl for use in rice and pyrithiobac-sodium for use in cotton, which have potent herbicidal activities and crop selectivity. Since these compounds include the pyrimidine ring and the carboxyl moiety in their chemical structure, they are referred to as pyrimidinyl carboxy (PC) herbicides. The sulfonanilide herbicides constituting another class of ALS-inhibiting herbicides were redesigned from PCs by replacing the oxy-bridge with a carbon bridge and the carboxyl group with a sulfonamide group. Pyrimisulfan is the representative that was found to have a wide range of herbicidal activities and crop selectivity for use in rice and turf grass. Details of this chemical class were first reported in 2000.