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Fast Oxy-Cope Rearrangements of Bis-alkynes: Competition with Central C−C Bond Fragmentation and Incorporation in Tunable Cascades Diverging from a Common Bis-allenic Intermediate

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posted on 17.12.2010, 00:00 by Runa Pal, Ronald J. Clark, Mariappan Manoharan, Igor V. Alabugin
Fast anionic oxy-Cope rearrangements of 1,5-hexadiyn-3,4-olates can be incorporated into cascade transformations which rapidly assemble densely functionalized cyclobutenes or cyclopentenones via a common bis-allenic intermediate. The competition between fragmentation, 4π-electrocyclic closure, and aldol condensation can be efficiently controlled by the nature of the acetylenic substituents. The rearrangement of bis-alkynes with two hydroxyl substituents opens a conceptually interesting entry in the chemistry of ε-dicarbonyl compounds and suggests a new approach to analogues of rocaglamide/aglafolin.