Syntheses, Crystal Structures and Herbicide Activities of Two Pyrazole Derivatives

Two novel N-acyl-3-phenylpyrazol benzophenones were designed and synthesized via cyclization and acylation with 1,3-diphenylpropane-1,3-dione and dimethylformamide dimethylacetal as the starting materials. Both of the newly synthesized compounds were characterized with IR, H-1 NMR, C-13 NMR, HRMS and single-crystal X-ray diffraction. 3-Phenyl-1-o-methylbenzoyl-pyrazole-4-benzophenone (5a) and 3-phenyl-1-p-fuorobenzoyl-pyrazole-4-benzophenone (5b) crystallize in triclinic system, space group P (1) over bar. The existence of p-pi conjunction effect resulted in correlative bond length shorter than the typical bond length in both of the crystals. The presence of van der Waals forces leads to the stability of the compounds.