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Solid-phase Synthesis of [4.4] Spirocyclic Oximes
Published on: February 6, 2019
Regiochemical control in intramolecular cyclization of methylene-interrupted epoxydiols
R S Narayan1, M Sivakumar, E Bouhlel
1Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
Abstract:
[reaction: see text] Methylene-interrupted epoxydiols have multiple regiochemical routes for cyclization. The 5-exo process is the most prevalent under acidic conditions. However, the regioselectivity can be controlled by the appropriate choice of acid promoter and pendant groups adjacent to the epoxide. The 5-exo product is obtained exclusively without the presence of a carbocation-stabilizing pendant group. Alkenyl and thiophenyl groups adjacent to the epoxide alter the regioselectivity and enable access to the 5-endo tetrahydrofuran and 6-endo tetrahydropyran products.
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