Straightforward Access to the NO-Donor Azasydnone Scaffold by Cascade Reactions of Amines
A novel one-pot cascade method for the assembly of valuable NO-donor azasydnone scaffold has been developed. This construction strategy involves a diazotization/azo coupling/elimination/double rearrangement cascade sequence of readily available amines. The current protocol enables the generation of a diverse array of azasydnones, including previously hardly accessible heteroaryl substituted azasydnones (25 examples, 70-97% yield) with a good functional group tolerance under very mild conditions. Preliminary NO-releasing studies revealed an ability of azasydnones to produce NO in a wide range of concentrations. This method provides a new approach to nitrogen-oxygen heterocycles with potential applications in medicine and material science.