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Synthesis of chiral spirocyclopropanepenicillanates via [2+1] annulation of 6-alkylidenepenicillanates and sulfur ylides
Authors: João Gonçalves; Ricardo Carvalho; Jéssica Macedo; Paloma Gonçalves; Inês Bártolo; Américo Alves; José Paixão; Nuno Taveira; Teresa Pinho e Melo
Ref.: J. Org. Chem. 90(29), 10225-10234 (2025)
Abstract: An unexplored reactivity of 6-(Z)-alkylidenepenicillanates was unveiled, describing the synthesis of compounds having a cyclopropane ring spiro-fused to the penicillanic core. This was achieved via the in situ generation of sulfur ylide intermediates from the corresponding sulfur salts, which react with 6-(Z)-alkylidenepenicillanates, leading to spirocyclopropanepenicillanates. The formal [2 + 1] cycloaddition, which involved the creation of three new chiral centers, proved to be diastereoselective, affording the new chiral spiropenicillanates in good yields. Notably, one spiro-beta-lactam exhibited excellent anti-HIV-1 activity.
