Asymmetric organocatalytic anthrone additions to activated alkenes

Alex Zea, Andrea Nekane R. Alba, Natalia Bravo, Albert Moyano, Ramon Rios

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Asymmetric organocatalytic additions of anthrones to activated alkenes are discussed. The reaction between anthrone or dithranol and α,β- unsaturated aldehydes is catalyzed by diphenylprolinol trimethylsilyl ether in toluene at -40 °C, giving the Michael adducts with good yields and enantioselectivities. Bifunctional amino-thioureas efficiently catalyze the additions of anthrones to both nitroalkenes and maleimides, and high enantioselectivities can be achieved in both instances at room temperature. In the case of nitroalkenes, a Michael addition takes exclusively place. Anthrone generally gives Diels-Alder cycloadducts in the reaction with maleimides, while dithranol affords the Michael adducts. Transition state working models in which the bifunctional catalyst binds simultaneously to the alkene and to the anthrone enolate account for the stereochemical outcome of these additions.

Original languageBritish English
Pages (from-to)2513-2529
Number of pages17
JournalTetrahedron
Volume67
Issue number14
DOIs
StatePublished - 8 Apr 2011

Keywords

  • Anthrones
  • Asymmetric catalysis
  • Diels-Alder cycloaddition
  • Michael addition
  • Organocatalysis

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