Studies on the synthesis and bioactivities of substituted dihydropyrazole derivatives

A novel and convenient synthetic method for 1-phenyl-3-substituted phenyl-4-triazolyldihy-dropyrazoles (1a-1b) and 3-substituted phenyl-4-triazolyldihydropyrazole (7) from alpha-triazolyl-beta-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 alpha,beta-unsaturated ketone with phenylhydrazine and their structures were confirmed by H-1 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.