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BIBTEX RIS

Bifunctional primary amine 2-aminobenzimidazole organocatalyst anchored to trans-cyclohexane-1,2-diamine in enantioselective conjugate additions of aldehydes

2016; Elsevier BV; Volume: 27; Issue: 2-3 Linguagem: Inglês

10.1016/j.tetasy.2015.12.004

ISSN

1362-511X

Autores

Talita de A. Fernandes, Pascuala Vizcaíno‐Milla, João M. J. M. Ravasco, Aitor Ortega‐Martínez, José M. Sansano, Carmén Nájera, Paulo R. R. Costa, Béla Fiser, Enrique Gómez‐Bengoa,

Tópico(s)

Synthesis and Catalytic Reactions

Resumo

Bifunctional chiral primary amine 8 containing an (S,S)-trans-cyclohexane-1,2-diamine scaffold and a 2-benzimidazole unit is used as a general organocatalyst for the Michael addition of α,α-branched aldehydes to nitroalkenes and maleimides. The reactions take place, with 20 mol % of catalyst in dichloromethane at rt for nitroalkenes and with 15 mol % catalyst loading in toluene at 10 °C for maleimides, in good yields and enantioselectivities. DFT calculations demonstrate the bifunctional character of this organocatalyst activating the aldehyde by enamine formation and the Michael acceptor by double hydrogen bonding.

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