Metal-free synthesis of N-sulfonylformamidines via skeletal reconstruction of sulfonyl oximonitriles

We developed for the first time an unprecedented domino reaction of sulfonyl oximonitriles with secondary amines to streamline the synthesis of N-sulfonylformamidines in decent to high yields under mild reaction conditions. In addition, scale-up experiments and late-stage functionalization of drugs were also performed. Preliminary studies indicate that the loss of a cyano-/benzyloxy-group and a sulfonyl migration process are involved in this reaction.