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Unexpected Participation of an Unconjugated Olefin during Nazarov Cyclization of Bridged Bicyclic Dienones


  • We thank NIGMS and NSF (CHE 0078974) for support of this work.


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Surprising rearrangements in a rigid system: A cyclopropyl ring is formed unexpectedly when a trienone substrate is subjected to the Nazarov cyclization (see scheme). The participation of the unconjugated alkene unit present in the substrate might be a consequence of the complete torquoselectivity of the initial electrocyclic closure. A subsequent rearrangement by a homo-1,5-hydrogen shift occurs cleanly to give the final product.