Enantioselective Michael addition of aldehydes to maleimides organocatalysed by chiral 1,2-diamines: an experimental and theoretical study |
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Authors: | Angel Avila Rafael Chinchilla Enrique Gómez-Bengoa Carmen Nájera |
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Affiliation: | 1. Departamento de Química Orgánica, Facultad de Ciencias, Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain;2. Departamento de Química Orgánica I, Universidad del País Vasco, Apdo. 1072, 20080 San Sebastíán, Spain |
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Abstract: | Simple and commercially available chiral 1,2-diamines were used as organocatalysts for the enantioselective conjugate addition of aldehydes, including α,α-disubstituted, to maleimides. The reaction was carried out in the presence of hexanedioic acid as an additive in aqueous solvents at room temperature. By employing (1S,2S)- and (1R,2R)-cyclohexane-1,2-diamine as organocatalysts, the corresponding Michael adducts bearing new stereocenters were obtained in high or quantitative yields with enantioselectivities of up to 92%, whereas the use of (1S,2S)-1,2-diphenylethane-1,2-diamine gave a much lower ee. Theoretical calculations were used to justify the observed sense of the stereoinduction. |
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