X-ray crystallography firmly established the relative stereochemistry of the title compound, C₁₇H₂₂N₂O₃. The absolute configuration was determined by use of 2-C-methyl-D-ribonolactone as the starting material. The compound exists as O—HN hydrogen-bonded chains of mol­ecules running parallel to the a-axis.

X-ray crystallography firmly established the relative stereochemistry of the title compound, C₁₆H₂₀N₂O₃. The acetonide ring adopts an envelope conformation with one of the O atoms as the flap and the piperidine ring adopts a slightly twisted boat conformation. The absolute configuration was determined by use of D-ribose as the starting material. The compound exists as O—HO hydrogen-bonded chains of mol­ecules running parallel to the b axis.