N-bromosuccinimide (NBS) as promoter for acylation of sydnones in the presence of acetic anhydride under neutral conditions

Various 4 - acetyl sydnones (2) can be prepared by reaction of the corresponding 3-aryl sydnones (1) with acetic anhydride at ∼110 °C promoted by N-Bromosuccinimide (NBS) as an effective reagent for acylation of sydnones under neutral conditions in satisfactory yields.