Ene reactions of 2-borylated α-methylstyrenes a practical route to 4-methylenechromanes and derivatives

Abstract : 4-Methylenechromanes were prepared via a three-step process from 2-borylated α-methylstyrenes. This sequence is based on a key glyoxylate-ene reaction catalyzed by scandium(iii) triflate. The resulting γ-hydroxy boronates, which cyclise to seven-membered homologues of benzoxaborole on silica gel, were cleanly oxidized with sodium perborate, and then cyclised under Mitsunobu conditions. Additionally, several further functional transformations of 4-methylenechromanes or their precursors were carried out to illustrate the synthetic potential of these intermediates.
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Submitted on : Friday, June 7, 2019 - 11:42:47 AM
Last modification on : Friday, June 14, 2019 - 1:39:06 PM

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Chaima Boureghda, Aurélie Macé, Fabienne Berrée, Thierry Roisnel, Abdelmadjid Debache, et al.. Ene reactions of 2-borylated α-methylstyrenes a practical route to 4-methylenechromanes and derivatives. Organic and Biomolecular Chemistry, Royal Society of Chemistry, 2019, 17 (23), pp.5789-5800. ⟨10.1039/c9ob00963a⟩. ⟨hal-02150447⟩

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