731797-99-2Relevant academic research and scientific papers
Formamides derived from N-methyl amino acids serve as new chiral organocatalysts in the enantioselective reduction of aromatic ketimines with trichlorosilane
Malkov, Andrei V.,Ston?ius, Sigitas,MacDougall, Kenneth N.,Mariani, Andrea,McGeoch, Grant D.,Ko?ovsky, Pavel
, p. 264 - 284 (2007/10/03)
Asymmetric reduction of N-aryl ketimines 1a-k, 43, and 45 with trichlorosilane can be catalyzed by new N-methyl l-amino acid-derived Lewis-basic organocatalysts, such as the valine-derived bisamide 3d (10 mol%), in toluene at room temperature with high enantioselectivity (≤92% ee). The structure-reactivity investigation shows that the product configuration is controlled by the nature of the side chain of the catalyst scaffold (e.g., i-Pr vs Me, as in 3d and 6e), so that catalysts of the same absolute configuration may induce the formation of the opposite enantiomers of the product. Arene-arene interactions between the catalyst and the incoming imine appear to be the prerequisite for asymmetric induction. This metal-free, organocatalytic protocol is competitive with the traditional, metal-catalyzed methodology.
Role of noncovalent interactions in the enantioselective reduction of aromatic ketimines with trichlorosilane
Malkov, Andrei V.,Mariani, Andrea,MacDougall, Kenneth N.,Kocovsky, Pavel
, p. 2253 - 2256 (2007/10/03)
Asymmetric reduction of ketimines 1 with trichlorosilane can be catalyzed by a new N-methyl L-valine derived Lewis basic organocatalyst, such as 4d, with high enantioselectivity. The structure-reactivity investigation suggests hydrogen bonding and arene-arene interactions between the catalyst and the incoming imine as the main factor determining the enantiofacial selectivity.
