Catalytic Asymmetric Synthesis of Cyclopentene-spirooxindoles Bearing Vinylsilanes Capable of Further Transformations.

Autor: Cobo AA; Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States., Armstrong BM; Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States., Fettinger JC; Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States., Franz AK; Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States.
Jazyk: angličtina
Zdroj: Organic letters [Org Lett] 2019 Oct 18; Vol. 21 (20), pp. 8196-8200. Date of Electronic Publication: 2019 Oct 01.
DOI: 10.1021/acs.orglett.9b02852
Abstrakt: We report a scandium-catalyzed [3 + 2] annulation of alkylideneoxindoles with allenylsilanes for the enantioselective formation of cyclopentene-spirooxindoles containing vinylsilanes. Using a Sc(OTf) 2 /PyBOX/BArF complex, the spiroannulation of allenylsilanes affords products with >94:6 dr and >90:10 er. The effect of the counterion and ligand to control selectivity is discussed. The transformation of the vinylsilane is demonstrated using cross-coupling, epoxidation, and Tamao-Fleming oxidation reactions. A series of competition experiments provide a comparison of nucleophilicity between allyl- and allenylsilanes.
Databáze: MEDLINE
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