Synthesis And Fungicidal Activity Of Acetophenone Derivatives Incorporating Substituted Phenylhydrazone Moiety

Acetophenone derivatives have attracted many pesticide researchers' attention because of their low toxicity to the human body,good bioactivity and easily modifying structure.A large number of acetophenone derivatives have been synthesized by modification of the substitutes at the benzene ring and the carbonyl group.Some of the compounds showed significant biological activity and a small amount of compounds have been used in agricultural production.In this paper,2,6-dihydroxyacetophenone was reacted with substituted phenylhydrazines respectively,to give the corresponding hydrazones,then carbonic ester groups were introduced to 2-and 6-position of the phenyl ring to design and synthesize forty-nine novel acetophenone derivatives incorporating substituted phenylhydrazone moiety.Fungicidal activity of the target compounds was preliminarily evaluated.Firstly,eight kinds of 2-?1-?2-?substituted phenyl?hydrazono?ethyl?benzene-1,3-diols were prepared by the reaction of 2,6-dihydroxyacetophenone with substituted phenylhydrazines,respectively,then the eight compounds were reacted with seven kinds of chloro-carbonic esters respectively,to give forty-nine dialkyl 2-?1-?2-?substituted phenyl?-hydrazono?ethyl?-1,3-phenylene bis?carbonate?.The structures of these target compounds were confirmed by FT-IR,1H NMR,13C NMR,MS and elemental analysis,and the structure of the compound D6 was confirmed by X-ray diffraction.The fungicidal activities of all target compounds against Fusarium graminearum,Botrytis cinerea,Rhizoctonia solani and Colletotrichum capsici were evaluated with the mycelial growth rate method.The results indicated that some of the target compounds exhibited remarkable fungicidal activities at the concentration of 10 ?g/mL.Therein,six compounds showed the inhibitory rates over 70%against Botrytis cinerea.Ten compounds showed the inhibitory rates over 70%against Rhizoctonia solani.And five compounds showed the inhibitory rates over 70%against Colletotrichum capsici.The EC₅₀ values of some selected compounds were determined.The compound F1 gave the best activity against Botrytis cinerea with EC₅₀ value of 1.6772 ?g/mL and against Colletotrichum capsici with EC₅₀ value of 3.1879 ?g/mL.The compound H1 showed the highest activity against Rhizoctonia solani with EC₅₀ value of 1.9051 ?g/mL.The preliminary analysis of structure-activity relationship indicated that the carbon chain length of carbonic ester goups had an obvious effect on fungicidal activity.The overall order of fungicidal activity was as follow,CH3>C2H5>n-C3H7>i-C3H7>n-C₄H₉?i-C₄H₉?Ph.