Turkish Journal of Chemistry
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-2(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.
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
COŞKUN, NECDET and TAT, FATMA TİRLİ (2004) "Synthesis and Reactivity of Tetrahydroimidazo [1,5-b][1,2,4]oxadiazol- 2(1H)-thiones," Turkish Journal of Chemistry: Vol. 28: No. 1, Article 1. Available at: https://journals.tubitak.gov.tr/chem/vol28/iss1/1