Stereodefined synthesis of cyclic amidines by domino 1,7-H shift and 6π electrocyclisation.

Unsaturated N2-sulfonyl amidines are transformed into valuable N-heterocyclic products when heated with BF2OTf. Mechanism studies suggest a domino 1,7-H shift, activating a C-H bond, followed by electrocylisation that results in stereodefined cyclic amidines.