David J. Hotchkiss

(S)-3-Dimethyl-amino-2-{(4S,5R)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-1,3-dioxolan-4-yl}-2-hydroxy-propanoic acid.

The Kiliani reaction on 1-deoxy-(N,N-dimethylamino)-d-fructose, itself readily available from reaction of dimethylamine and d-glucose, proceeded to give access to the title β-sugar amino acid, C15H27NO7. X-ray crystallography determined the stereochemistry at the newly formed chiral center. There are two molecules in the asymmetric unit; they are related by a pseudo-twofold rotation axis and have very similar geometries, differing only in the conformation of one of the acetonide rings. All the acetonide rings adopt envelope conformations; the flap atom is oxygen in three of the rings, but carbon in one of them. There are two strong hydrogen bonds between the two independent molecules, and further weak hydrogen bonds link the molecules to form infinite chains running parallel to the a axis.

3,5-O-Isopropyl­idene-2-C-methyl-d-xylonolactone

The ring size of both the lactone and the ketal protecting group in the title compound, C9H14O5, have been established by X-ray crystallographic analysis. The crystal structure consists of hydrogen-bonded spirals parallel to the b axis.