Synthesis and Reactivity of Tetrahydroimidazo [1,5-b][1,2,4]oxadiazol-2(1H )-thiones

Authors : Necdet COŞKUN, Fatma Tirli TAT

Pages : 1-8

View : 19 | Download : 11

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :1,3-Dipolar cycloaddition of imidazoline 3-oxides 1 with methylisothiocyanate proceeds regio- and diastereoselectively to give tetrahydroimidazo[1,5-b][1,2,4]oxadiazol-2insert ignore into journalissuearticles values(1H);-thiones 3 in high yields. The cis configuration of the adducts was proved by our double cis elimination test as well as by NOESY experiments. Adducts 3a-c undergo ring opening at reflux in acetonitrile to give imidazoles while 3d-e undergo retro dipolar cycloaddition to give the starting nitrones 1d-e. The imidazooxadiazol-2-thiones 3a-e were treated with concentrated HCl in ethanol at 50 °C to give the corresponding 4H-[1,2,4]oxadiazole-5-thione only in cases in which the substituent at C-6 is an aryl.
Keywords : Imidazoline 3 oxides, 1, 3 Dipolar cycloaddition, Tetrahydroimidazo 1, 5 b 1, 2, 4 oxadiazol 2 1H, thiones, 4H 1, 2, 4 oxadiazole 5 thione