1: hydroxyacetaldehyde With Zn[(L)-proline]2 in water T=20°C; 168 h; 2: acetic acid With pyridine; 4-(N,N-dimethlyamino)pyridine 24 h; Further byproducts given. Title compound not separated from byproducts;

1) 4 h, pyridine, 2) 12 h, pyridine; Yield given. Multistep reaction. Yields of byproduct given;