STEREOSELECTIVE REACTIONS OF LITHIUM ENOLATES DERIVED FROM N-BOC PROTECTED PYROGLUTAMIC ESTERS

Authors
EZQUERRA J PEDREGAL C RUBIO A YRURETAGOYENA B ESCRIBANO A SANCHEZFERRANDO F
Citation
J. Ezquerra et al., STEREOSELECTIVE REACTIONS OF LITHIUM ENOLATES DERIVED FROM N-BOC PROTECTED PYROGLUTAMIC ESTERS, Tetrahedron, 49(38), 1993, pp. 8665-8678
Citations number
41
Categorie Soggetti
Chemistry Inorganic & Nuclear
Journal title
Tetrahedron → ACNP
ISSN journal
00404020
Volume
49
Issue
38
Year of publication
1993
Pages
8665 - 8678
Database
ISI
SICI code
0040-4020(1993)49:38<8665:SROLED>2.0.ZU;2-F
Abstract
The lithium enolates of N-Boc protected pyroglutamic ethyl or tert-but yl esters react with electrophiles in good yield without epimerization of the chiral centre. With benzyl bromides the process is stereospeci fic, yielding exclusively the trans isomer. However, with other reacti ve electrophiles a 2:1 trans/cis diastereomeric mixture was obtained, regardless of the steric bulk of the ester group.