One-Pot Protocol to Functionalized Benzopyrrolizidine
Catalyzed Successively by Rh<sub>2</sub>(OAc)<sub>4</sub> and Cu(OTf)<sub>2</sub>: A Transition Metal–Lewis Acid Catalysis Relay
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Abstract
4-<i>N</i>-Allylarylpropylamino-1-sulfonyl
triazoles
are converted to structurally unique benzopyrrolizidinyl sulfonamides
in a one-pot operation. Intramolecular capture of rhodium carbene
with arylamino nitrogen gives rise to the formation of an ammonium
ylide immediate. A [2,3]- or [1,2]-rearrangement occurs to give a
2-allylpyrrolidinyl-2-carbimine intermediate which undergoes Cu(OTf)<sub>2</sub> catalyzed aza-Friedel–Crafts cyclization to finish
a highly functionalized tricyclic system decorated with a synthetically
difficult quaternary carbon center, a sulfonamide group, and an allyl
segment