Crystallographic and conformational analysis of 2-methyl-3-(2-nitro-phenyl)-4-phenyl-[1,2,4]oxadiazolidin-5-one

Bisnitrone: New Starting Material for Heterocyclic Poly(1,2,4-oxadiazolidin-5-one) via Polycycloaddition with Diisocyanate and Urethane Prepolymer

“…Nitrones are typical 1,3-dipoles involving 4π-electrons which readily undergo cycloaddition with a variety of suitable unsaturated compounds. − The cycloaddition of mononitrones with monoisocyanates was first described by Goldschmidt and Beckmann in 1890. − The structure of the nitrone isocyanate adducts were later established as 1,2,4-oxadiazolidin-5-ones, − a motif found in alkaloids. , 1,2,4-oxadiazolidin-5-one derivates are potential candidates for the development of pharmaceutical and other biologically relevant substances, because they are configurationally stable heterocycles, which combine structural features of barbituric acid and hydantoin derivates, compounds with broad medical applications. , Isocyanates like 4,4′-methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI) are commonly used in industrial polyurethane production. , However, diisocyanates have not been used in 1,3-dipolar polycycloaddition with bisnitrones so far. Beside the wide range of described low molecular weight five-membered heterocyclic ring systems that have been synthesized via nitrone cycloaddition, − nitrones have been applied in polymer chemistry in recent years .…”