Unsaturated N-sulfonamides undergo a Rh(III)-catalyzed allylic C(sp(3))-H activation followed by insertion with an exogenous internal alkyne. The reaction generates [3.3.0], [4.3.0], and [5.3.0] azabicyclic structures with excellent diastereoselectivity. Deuterium labeling experiments implicate a 1,3-Rh shift as a key step in the mechanism.
Keywords: 1,3-migration; 4π-electrocyclization; CH insertion; azabicycles; rhodium.
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