Diastereoselective synthesis of 2-alkylated 4-silylxyproline esters

Citation
T. Sato et al., Diastereoselective synthesis of 2-alkylated 4-silylxyproline esters, J CHEM S P1, (20), 2001, pp. 2623-2631
Citations number
28
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Chemistry & Analysis","Organic Chemistry/Polymer Science
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 1
ISSN journal
1472-7781 → ACNP
Issue
20
Year of publication
2001
Pages
2623 - 2631
Database
ISI
SICI code
1472-7781(20011021):20<2623:DSO24E>2.0.ZU;2-#
Abstract
Treatment of the 4-silyloxy-N-Boc-L-proline methyl ester 1 with allyl bromi de in the presence of LDA in THF at, -78 degreesC gives a mixture of the (2 S,4R)- and (2R,4R)-2-(prop-2-enyl)-4-silyloxy-N-Boc-L-proline esters 2a and 2b in 75% combined yield in the ratio 53:47. In contrast, similar treatmen t of the (-)- and (+)-menthyl esters 5 and 6 gives a mixture of allylated p roducts 7a,b and 8a,b in the ratio 75:25 and 89:11, respectively. Reaction of 6 with methyl iodide and propyl iodide also give the corresponding 2-alk ylated esters 16a and 16b in a highly diastereoselective manner (94:6 and 9 3:7, respectively).