Résumé
Abstract
The addition of the lithium derivative of N-Boc 4-ethynyl-2,2-dimethyl-1,3-oxazolidine to tetra-O-benzyl-D-gluco- and galactonolactone and 2-azido-2-deoxy congeners afforded the corresponding ethynyl ketoses in fairly good yields (64-78%). Following the conversion of the ketoses into O-acetates and removal of the acetoxy group by silane reduction, the resulting β-linked ethynyl glycosides were transformed into N-Boc C-glycosyl α-aminobutyric acids by reduction of the triple bond using H
2
/Pd(OH)
2
and oxidative cleavage of the oxazolidine ring using the Jones’ reagent. After the removal of O-benzyl groups of the carbohydrate moieties by hydrogenation and the reduction of azido to amino group, all compounds were subjected to acetylation and isolated as O- and N-acetyl derivatives. The C-glycosyl α-amino acids prepared correspond to methylene isosteres of O-glycosyl serines.