Environmentally benign metal-free decarboxylative aldol and Mannich reactions
Baudoux, J; Lefebvre, P; Legay, R; Lasne, MC; Rouden, J
| HERO ID | 4933656 |
|---|---|
| In Press | No |
| Year | 2010 |
| Title | Environmentally benign metal-free decarboxylative aldol and Mannich reactions |
| Authors | Baudoux, J; Lefebvre, P; Legay, R; Lasne, MC; Rouden, J |
| Journal | Green Chemistry |
| Volume | 12 |
| Issue | 2 (2010) |
| Page Numbers | 252-259 |
| Abstract | Aiming at the development of green and efficient C-C bond formations (aldol and Mannich reactions), the decarboxylative nucleophilic addition of malonic acid half ester to imines or aldehydes under mild metal-free conditions was studied. A careful control of the temperature and the appropriate choice of the organic base allowed us to obtain [small beta]-amino esters or [small beta]-hydroxy esters including [small alpha]-substituted and [small alpha],[small alpha]-disubstituted ones in moderate to excellent yields. 1H NMR monitoring of the reaction unveiled two distinct mechanisms depending on the hemimalonate used. With the unsubstituted substrate, a carboxylic acid intermediate was isolated upon acid quench resulting from the nucleophilic addition of the putative enol carboxylate anion of the hemimalonate to imines/aldehydes before CO2 loss. With substituted hemimalonates, the reaction likely involved an enolate which then added to imines/aldehydes or was competitively protonated. According to the base used, the reaction can be carried out either under solvent free-conditions or in an ionic liquid under mild conditions. |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Keyword | Anions; Temperature; Carboxylic acids; Solvents; NMR; green development; Carbon dioxide; Aldehydes; Esters |