CHIRAL LEWIS-ACID CONTROLLED SYNTHESIS (CLAC SYNTHESIS) - CHIRAL LEWIS-ACIDS INFLUENCE THE REACTION COURSE IN ASYMMETRIC ALDOL REACTIONS FOR THE SYNTHESIS OF ENANTIOMERIC DIHYDROXYTHIOESTER DERIVATIVES IN THE PRESENCE OF CHIRAL DIAMINES DERIVED FROM L-PROLINE

Citation
S. Kobayashi et M. Horibe, CHIRAL LEWIS-ACID CONTROLLED SYNTHESIS (CLAC SYNTHESIS) - CHIRAL LEWIS-ACIDS INFLUENCE THE REACTION COURSE IN ASYMMETRIC ALDOL REACTIONS FOR THE SYNTHESIS OF ENANTIOMERIC DIHYDROXYTHIOESTER DERIVATIVES IN THE PRESENCE OF CHIRAL DIAMINES DERIVED FROM L-PROLINE, Chemistry, 3(9), 1997, pp. 1472-1481
Citations number
75
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry
Journal title
Chemistry → ACNP
ISSN journal
0947-6539
Volume
3
Issue
9
Year of publication
1997
Pages
1472 - 1481
Database
ISI
SICI code
0947-6539(1997)3:9<1472:CLCS(S>2.0.ZU;2-Y
Abstract
Both enantiomers of 2,3-dihydroxythioester derivatives were prepared w ith almost perfect stereochemical control by chiral Lewis acid control led synthesis (CLAC synthesis). CLAC synthesis means synthesis of all individual diastereomers or enantiomers from the same starting materia ls by designing chiral Lewis acids. For example, Z)-1-ethylthio-1-(tri methylsiloxy)-2-(tert-butyldi methylsiloxy)ethene (1) reacted with ald ehydes in the presence of chiral tin(II) Lewis acids using (S)-1-methy l-2-[(isoindolinyl)methyl]pyrrolidine (4) and (S)-1-methyl-2-[(indolin yl)methyl]pyrrolidine (5) to afford enantiomeric dihydroxythioester de rivatives. Chiral diamines 4 and 5, which were readily prepared from L -proline, differ only in the fusion point of the benzene ring connecte d to the pyrrolidine moiety. The unique selectivities were ascribed to the conformational difference between the chiral tin(II) Lewis acids of chiral diamines 4 and 5, and the function of chiral sources for obt aining high selectivities has also been clarified.