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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Re2O7-Catalyzed Approach to Spirocyclic Ether Formation from Acyclic Precursors: Observation of Remote
Cephas Afeke1, Youwei Xie1, Paul E Floreancig1
1Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States.
Abstract:
Ketones that are flanked by an allylic alcohol and an alkene isomerize to spirocyclic ethers in the presence of Re2O7 through allylic alcohol transposition, oxocarbenium ion formation, and Prins cyclization. These processes provide significant increases in molecular complexity, with multiple stereocenters being set relative to a stereocenter in the substrate. Stereoselectivity arises from the initial reversible steps being more rapid than the final step, thereby allowing for thermodynamically controlled stereochemical equilibration prior to product formation.
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