Microwave-assisted organocatalytic anomerization of alpha-C-glycosylmethyl aldehydes and ketones.
The use of l-proline (30 mol %) and MW irradiation (13 W) with cooling promotes in a few hours the almost quantitative anomerization of alpha-C-glycosylmethyl aldehydes into beta-isomers. An open-chain enamine-based mechanism is postulated for this transformation. The anomerization of alpha-ketones was instead achieved by the pyrrolidine/TFA couple and MW irradiation at 120 degrees C (enamine mechanism) and by DBU as Brønsted base (enolate mechanism).
Massi
Alessandro
A
Dipartimento di Chimica, Laboratorio di Chimica Organica, Università di Ferrara, Via L. Borsari 46, I-44100 Ferrara, Italy. msslsn@unife.it
Nuzzi
Andrea
A
Dondoni
Alessandro
A
D000447:Aldehydes / Q000737:chemistry* / Q000528:radiation effects*; D002236:Carbohydrate Conformation; D002384:Catalysis; D007659:Ketones / Q000737:chemistry* / Q000528:radiation effects*; D008872:Microwaves; D015394:Molecular Structure; D011392:Proline / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D007659:Ketones; D011392:Proline