N,N'-Bis­[(R)-2-hydroxy-2-phenyl­ethyl]-N,N'-bis­[(S)-1-phenyl­ethyl]­pyridine-2,6-dicarbox­amide: stabilization of an asymmetric conformer through the formation of a double intramolecular hydrogen bond

The title compound, C₃₉H₃₉N₃O₄, although having potential C₂ molecular symmetry, crystallizes as an asymmetric conformer, due to a couple of strong intramolecular hydrogen bonds involving hydroxyl groups and a pyridine N atom. This geometrical feature explains why this compound behaves as a poor chiral inductor for asymmetric synthesis.

(2R,3S,4R)-1,2,4,5-Tetra­acetoxy-3-methoxy­pentyl acetate

The title compound, C₁₆H₂₄O₁₁, formed by acetolysis of a D-xylo­furan­ose derivative, has an open-chain structure adopting a hindered conformation in the solid state.

N-(2-Cyano­propan-2-yl)isobutyramide

The title compound, C₈H₁₄N₂O, is stabilized in the solid state as a keto tautomer. The asymmetric unit contains two mol­ecules with different conformations. In the crystal structure, inter­molecular N—H...O hydrogen bonds of moderate strength link the mol­ecules into chains along the c axis.