A new direct synthesis of cinnamic acids from aromatic aldehydes and aliphatic carboxylic acids in the presence of sodium borohydride

Cinnamic acids have been prepared in 59–86% yields by a new direct synthesis from aromatic aldehydes and aliphatic carboxylic acids in the presence of sodium borohydride and N-methyl-2-pyrrolidinone (NMP) as solvent, at reflux (185–190°C), for 9–12 hours. Without sodium borohydride, this reaction is not possible.