Synthesis and antifungal activity of 1/3 phenyl-6,7,8,9-tetrahydro[1]benzotheino[3,2-e] [2,3-d]thiazolo[3,2-a]pyrimidin-5(H) ones

S-Phenacyl-N-(3-carbethoxy-4,5,6,7-tetrahydro-1-benzothien-2-yl) thioureas (la-e) were synthesized by reaction between ethyl-2-amino -4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate and alpha-thiocynoacetophenone. la-e on cyclization gave 3-carbethoxy-2-(2'-imino-4'-phenyl thiazolidin-3'-yl) 4,5,6,7-tetrahydro-1 benzothiophenes (IIa-e) as intermediates which on further cyclization yielded an angular product 1-phenyl-6,7,8,9-tetrahydro [1] benzothieno [3,2-e] thiazolo [3,2-a] pyrimidin -5(H)-one (IVa-e). Similarly Va-e were obtained from IIIa-c. Antifungal activity of the prepared compounds (la-e), (IVa-e) and (Va-e) have been evaluated and compared with Dithan M-45 against Alternaria Solani and Puccinia graminis tritici and the results correlated with their structural features.