1,2-5,6-DI-O-ISOPROPYLIDENE-ALPHA-D-GULOFURANOSE AS A CHIRAL AUXILIARY IN THE DIASTEREOSELECTIVE C-METHYLATION OF ESTER ENOLATES - THE INFLUENCE OF THE BASE ON THE STEREOCHEMISTRY OF ENOLATE FORMATION AND ALKYLATION

Authors
MULZER J HIERSEMANN M BUSCHMANN J LUGER P
Citation
J. Mulzer et al., 1,2-5,6-DI-O-ISOPROPYLIDENE-ALPHA-D-GULOFURANOSE AS A CHIRAL AUXILIARY IN THE DIASTEREOSELECTIVE C-METHYLATION OF ESTER ENOLATES - THE INFLUENCE OF THE BASE ON THE STEREOCHEMISTRY OF ENOLATE FORMATION AND ALKYLATION, Liebigs Annalen, (5), 1996, pp. 649-654
Citations number
34
Categorie Soggetti
Chemistry
Journal title
Liebigs Annalen → ACNP
ISSN journal
09473440
Issue
5
Year of publication
1996
Pages
649 - 654
Database
ISI
SICI code
0947-3440(1996):5<649:1AACA>2.0.ZU;2-5
Abstract
The C methylation of the carbohydrate-derived O-chiral esters 5a-d to derivatives 8 proceeds with (R) selection of 1:1 to 10:1 and depends p rimarily on the base used for enolate generation. Lithium 2,2,6,6-tetr amethylpiperide (LTMP) shows the highest and lithium hexamethyldisilaz anide (LHMDS) the lowest selection. These results are interpreted in t erms of a ''post-enolization complex'' involving the lithium amide bas e.