Investigation of oxidopyrylium-alkene [5+2] cycloaddition conjugate addition cascade (C3) sequences
Justin A Simanis1, C Marshall Law, Erica L Woodall
1Department of Chemistry, Illinois State University, Normal, IL 61790-4160, USA. tmitche@ilstu.edu.
Abstract:
Novel oxidopyrylium-alkene [5+2] cycloaddition conjugate addition cascade (C(3)) sequences are described. Various acetoxypyranone-alkenes with pendant nucleophiles undergo [5+2] cycloaddition followed by conjugate addition from the concave face of the intermediate pyranone toward bridged, tetracyclic ethers. In several cases, 3 new rings, 4 new bonds, and 6 new contiguous stereocenters are constructed with excellent diastereoselectivity. Finally, an asynchronous concerted reaction pathway is proposed to explain the high diastereoselectivity of the oxidopyrylium-alkene [5+2] C(3).
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