Various 4 - acetyl sydnones (2) can be prepared by reaction of the corresponding 3-aryl sydnones (1) with aceticanhydride at ∼110 °C promoted by N-Bromosuccinimide (NBS) as an effective reagent for acylation of sydnones underneutralconditions in satisfactory yields.
1,3-Dibromo-5,5-dimethylhydantoin (DBH) as an efficient promoter for acetylation of 3-arylsydnones in the presence of acetic anhydride under neutral conditions
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 aceticanhydrideunderneutralconditions in satisfactory yields.