Chiral auxiliary based approach toward the synthesis of C-glycosylated amino acids

[GRAPHICS] In a chiral auxiliary based method C-glycosylated amino acids can be obtain ed by a 1,3-dipolar cycloaddition of a chiral glycine equivalent and C-1 al lyl- or vinyl-derived carbohydrate building blocks as the key step. The pro ducts are formed regio- and diastereoselectively. Reductive cleavage of the N-O bond of the isoxazolidine and of the chiral auxiliary leads to C-glyco sylated amino acids. The use of (-)-menthone to (+)-menthone as the auxilia ry leads to the corresponding diastereomers.