Carbon‐13 NMR Studies of 3‐Aryl‐4‐(5‐aryl‐Δ 2‐1,2,4‐oxadiazolin‐3‐yl)sydnones and 3‐Aryl‐4‐(5‐aryl‐1,2,4‐oxadiazol‐3‐yl)sydnones

The 13C NMR spectra of twelve 3-aryl-4-(5-aryl-Δ2-l,2,4-oxadiazolin-3-yl)sydnones and twelve 3-aryl-4-(5-aryl-l,2,4-oxadiazol-3-yl)sydnones have been measured and assigned by means of proton-noise decoupling and DEPT-experiments. The coupling constants were determined by means of gated decoupling, and NOE effects were observed by comparison of proton-decoupled and inverse-gated decoupled spectra. Differences shown by the oxadiazoline and the oxadiazole rings and the substitution effects are discussed.