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Novel chiral hydrogen bond donor catalysts based on a 4,5-diaminoxanthene scaffold: application to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes
- Source :
- Tetrahedron Letters. 52:987-991
- Publication Year :
- 2011
- Publisher :
- Elsevier BV, 2011.
-
Abstract
- Novel chiral hydrogen bond donor catalysts based on a 4,5-diamino-9,9′-dimethylxanthene skeleton were designed and synthesized. Among the phenylurea-amide hybrid molecules prepared from various natural/unnatural chiral amino acids, the phenylalanine-derived catalyst, and the proline-derived catalyst were successfully applied to enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes. Using 2-acetylcyclopentanone and 2-methoxycarbonylcyclopentanone as prochiral nucleophiles, asymmetric conjugate addition to β-aryl nitroalkenes proceeded with good diastereoselectivity to provide the corresponding products bearing an all-carbon quaternary stereocenter in excellent yield with up to 95% ee.
Details
- ISSN :
- 00404039
- Volume :
- 52
- Database :
- OpenAIRE
- Journal :
- Tetrahedron Letters
- Accession number :
- edsair.doi...........f7736d997e24f3730d7e9bfd4a40232a