Synthesis of the First Representatives of new 3,3a‐Dihydro‐1H‐Imidazo[4′,5′:4,5]Imidazo[2,1‐b]thia(selena)zole Heterocyclic Systems with Fungicidal Activity

Abstract The first representatives of new fused tricyclic heterosystems, namely 3,3a‐dihydro‐1 H ‐imidazo[4′,5′:4,5]imidazo[2,1‐ b ]thiazoles and 3,3a‐dihydro‐1 H ‐imidazo[4′,5′:4,5]imidazo[2,1‐ b ][1,3]selenazoles have been synthesized through the regioselective reaction of diethyl acetylenedicarboxylate with semithioglycolurils, thioglycolurils or selenoglycolurils. Study of antifungal properties of the obtained compounds against Venturia inaequalis ( V . i .), Rhizoctonia solani ( R . s .), Fusarium oxysporum , Fusarium moniliforme , Bipolaris sorokiniana ( B . s .) and Sclerotinia sclerotiorum phytopathogenic fungi has been performed. Tested compounds possessed good inhibition activity against R. s ., B. s . with 45–94 % by mycelium growth inhibition test method, which were more active than the well–known azole fungicide triadimefon as positive control. The best active thiazole derivative was established to be effective against R . s . (94 %), B.s . (65 %) and V . i . (60 %). Two selenazole derivatives showed good activity with 69 % inhibition against R. s .