Discovery of novel Propionamide‐Pyrazole‐Carboxylates as Transketolase‐inhibiting herbicidal candidates

BACKGROUND Transketolase (TKL, EC 2.2.1.1) is a key enzyme in the pentose phosphate pathway and Calvin cycle, and is expected to act as a herbicidal site‐of‐action. On the basis of TKL, we designed and synthesized a series of 1‐oxy‐propionamide‐pyrazole‐3‐carboxylate analogues and evaluated their herbicidal activities. RESULTS Methyl 1‐methyl‐5‐((1‐oxo‐1‐((4‐(trifluoromethyl)phenyl)amino)propan‐2‐yl)oxy)‐1 H ‐pyrazole‐3‐carboxylate (C23) and methyl 1‐methyl‐5‐((1‐oxo‐1‐((perfluorophenyl)amino)propan‐2‐yl)oxy)‐1 H ‐pyrazole‐3‐carboxylate (C33) were found to provide better growth‐inhibition activities against Digitaria sanguinalis root than those of nicosulfuron, mesotrione and pretilachlor at 200 mg L −1 using the small‐cup method. These compounds were also identified as promising compounds in pre‐emergence and postemergence herbicidal‐activity experiments, with relatively good inhibitory effects toward Amaranthus retroflexus and D. sanguinalis at 150 g ai ha −1 . In addition, enzyme inhibition assays and molecular docking studies revealed that C23 and C33 interact favourably with Sv TKL ( Setaria viridis TKL). CONCLUSION C23 and C33 are promising lead TKL inhibitors for the optimization of new herbicides.