No abstract

Oxadiazole derivatives R 0290 1,3-Dibromo-5,5-dimethylhydantoin (DBH) as an Efficient Promoter for Acetylation of 3-Arylsydnones in the Presence of Acetic Anhydride under NeutralConditions. -Optimization experiments reveal that equimolar amounts of sydnone (I) and 1,3-dibromo-5,5-dimethylhydantoin give the best results. -(AZARIFAR*, D.; BOSRA, H. G.; TAJBAKSH, M.; J. Heterocycl. Chem. 44 (2007) 2, 467-469; Dep. Chem., Coll. Sci., Univ. Bu-Ali Sina, Hamadan 65174, Iran; Eng.) -H. Haber 31-107

1,3‐Dibromo‐5,5‐dimethylhydantoin (DBH) has been found to efficiently promote the conversion of various 3‐arylsydnones to their 4‐acetyl congeners in the presence of acetic anhydride under neutral conditions in satisfactory yields.

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DFT studies indicated that a hetero-Diels–Alder reaction of 4-phosphinyl and 4-phosphonyl-1,2-diaza- and 1,2-oxaza-1,3-butadienes with some olefins take place via an asynchronous concerted mechanism through endo or exo transition states.