Organocopper triggered cyclization of conjugated dienynes via tandem S N 2′/Alder-ene reaction

Tanzeel Arif (1) , Cyril Borie (1) , Marion Jean (2) , Nicolas Vanthuyne (2) , Michèle Bertrand (1) , Didier Siri (1) , Malek Nechab (1)

1 ICR - Institut de Chimie Radicalaire
2 ISM2 - Institut des Sciences Moléculaires de Marseille

Propargylic carbonates were converted to indenes through a S N 2'/Alder-ene cascade triggered by organocopper reagents. The reaction tolerates different organocopper species generated either from organolithiums or Grignard reagents. A catalytic version of this strategy could be devised using either copper or iron catalysts. Attempts to transfer chirality from an enantioenriched substrate revealed a moderate chirality conversion because of a low discrimination between the two faces of the internal olefinic partner with these typical substrates. The theoretical investigation supports a concerted closed-shell mechanism and highlights the influence of the substituents on the activation parameters and on the synchronicity of C-H bond breaking and CC bond forming during the Alder-ene step.

Domains: Chemical Sciences

Tanzeel Arif, Cyril Borie, Marion Jean, Nicolas Vanthuyne, Michèle Bertrand, et al.. Organocopper triggered cyclization of conjugated dienynes via tandem S N 2′/Alder-ene reaction. Organic Chemistry Frontiers, 2018, 5 (5), pp.769-776. ⟨10.1039/c7qo00288b⟩. ⟨hal-02053476⟩