Studies on the synthesis and bioactivities of substituted dihydropyrazole derivatives

A novel and convenient synthetic method for l-phenyl-3-substituted phenyl-4-triazolyldihy-dropyrazoles (1a-1b) and 3-substituted phenyl-4-triazolyldihydropyrazole (7) from α-triazolyl-β-alkoxyacetophenone 4 was described. The reaction condition was studied and optimized. 1, 3, 4, 5-Multi-substituted dihydropyrazole 1c-1h were prepared through the general cyclization of α,β-unsaturated ketone with phenylhydrazine and their structures were confirmed by ¹H NMR, MS and elemental analysis. Furthermore, 3,5-substituted dihydropyrazole 6(or 7) reacted with methyl (or ethyl) chloroformate and potassium thiocyanate to afford 1,3,5-(or 4-)substituted dihydropyrazole 2a-2l. The results of preliminary bioassay presented that almost all compounds showed fungicidal, herbicidal and plant growth regulatory activities.