Method for preparing chloramphenicol from nitromethane

The invention relates to a method for preparing a broad spectrum antibiotic of chloramphenicol. The method comprises the following steps of: synthesizing (R)-2-nitro-1-(4-chlorophenyl)ethanol by using p-chlorobenzaldehyde and nitromethane as raw materials in the presence of a chiral catalyst; reacting with formaldehyde to obtain (1R,2R)-2-nitro-1-(4-chlorophenyl)-1,3-propanediol, and performing catalytic hydrogenation to obtain (1R,2R)-2-amino-1-(4-chlorophenyl)-1,3-propanediol; and performing dichloro acetylization and nitro substitution on the intermediate to obtain the chloramphenicol. By the method, the common chiral resolution and aluminum isopropoxide reduction in the industry at present can be avoided, three wastes are reduced, the raw materials and reagents are cheap and readily available, the method comprises a few synthesizing steps, the yield is high, and the method is more suitable for industrial production.