New auxiliaries for copper-catalyzed asymmetric Michael reactions: Generation of quaternary stereocenters at room temperature

Citation
J. Christoffers et A. Mann, New auxiliaries for copper-catalyzed asymmetric Michael reactions: Generation of quaternary stereocenters at room temperature, CHEM-EUR J, 7(5), 2001, pp. 1014-1027
Citations number
76
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry
Journal title
CHEMISTRY-A EUROPEAN JOURNAL
ISSN journal
0947-6539 → ACNP
Volume
7
Issue
5
Year of publication
2001
Pages
1014 - 1027
Database
ISI
SICI code
0947-6539(20010302)7:5<1014:NAFCAM>2.0.ZU;2-I
Abstract
Dialkyl amides of L-valine, L-isoleucine, and L-tert-leucine (2) are excell ent chiral auxiliaries for the construction of quaternary stereocenters at ambient temperature. Enaminoesters 3, prepared from these auxiliaries 2 and Michael donors 1, undergo a copper-catalyzed asymmetric Michael reaction w ith methyl vinyl ketone (MVK, 4) to afford products 5 in 70-90% yield and 9 0-99% ee (enantiomeric excess). The exclusion of moisture or oxygen is not necessary. The auxiliaries 2 are readily available by standard procedures. After workup they can be recovered almost quantitatively.