Cellulose nanofibers obtained from wood pulp by TEMPO-mediated oxidation acted as a chiral enhancer in direct aldol reactions of 4-nitrobenzaldehyde and cyclopentanone with (S)-proline as an organocatalyst. Surprisingly, catalytically inactive TEMPO-oxidized cellulose nanofibers enriched the (R,R)-enantiomer in this reaction, affording 89% ee in thesynform with a very high yield (99%). Conversely, nanocellulose-free (S)-proline catalysis resulted in poor selectivity (64% ee,synform) with a low yield (18%). Green organocatalysis occurring on nanocellulose solid surfaces bearing regularly aligned chiral carbons on hydrophobic crystalline facets will provide new insight into asymmetric synthesis strategies for interfacial catalysis.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)