Rapid Access to Nitrogenous Heterobicycles via RhIII -Catalyzed Isomerization from Alkynes to Allenes.

We show that N-alkynylnitrones are efficiently converted to nitrogenous heterobicyclic compounds with a nitrogen atom at the bridgehead position by using a RhIII -catalyst. Our mechanistic studies suggest that the reaction proceeds via an allene intermediate, which is generated in situ through RhIII -catalyzed isomerization of the alkyne group.