Synthesis And Biological Activities Of Benzothiazole Derivatives

Benzothiazole derivatives have been widely used in pesticidal and medicinal fields because of their good biological activities.With benzo-thiazole as the lead compound,22 derivatives of 3-((5-aryl-1,3,4-oxadia zol-2-yl)methyl)benzo[d]thiazol-2(3H)-ones and 18 substitued-3-aryl-1,2,4-triazolo[3,4-b]benzothiazoles and 31 derivatives of 6-methoxybenzo[4,5]thiazolo[2,3-c][1,2,4]triazole-3(2H)-thione were prepared.All of them are new compounds.It may be summarized as follows:1.A series of new 3-((5-aryl-1,3,4-oxadiazol-2-yl)methyl)benzo[d]thiazol-2(3H)-ones were synthesized by reaction of(5-substituted-2-oxo benzothiazolin-3-yl)-acetohydrazide with various aromatic acids in POCl3 under reflux condition.The structures of the title compounds were con-firmed by 1H-NMR,13C-NMR,IR,MS and elemental analysis.Further-more,the structure of compound(4i)was determined by single-crystal X-ray diffraction.The preliminary bioassy results indicated that some of them showed moderate inhibition activity against Colletotrichum orbiculare,Botrytis cinerea and Rhizoctonia solani.However,their herb icidal activities were weak.2.Eighteen new substitued-3-aryl-1,2,4-triazolo[3,4-b]benzothiazo-les were obtained by refluxing substituted-2-hydrazinobenzothiazole with various substituted benzoic acids in POCl3 under reflux condition.The structures of the title compounds were characterized by 1H-NMR,EI-MS and elemental analysis.The preliminary bioassy results indicated that some of them showed moderate inhibition activity against Rhizoctonia solani,Ascochyta citrullina,Fusarium oxysporum f.sp cubense and Col-letotrichum nicotianae.Unexpectedly,some of them possessed certain promotion activity against Botrytis cinerea.3.Thirty-one new 6-methoxybenzo[4,5]thiazolo[2,3-c][1,2,4]triazol-3(2H)thione derivatives were synthesized by reacting substituted-2-hyd-razinobenzothiazole with chlorides and chloroformates in THF.The stru-ctures of the title compounds were characterized by 1H-NMR.