Re-examination of Nucleophilic Substitutionin Chlorokojic Acid

Summary.

 Chlorokojic acid was reacted with S₂O₃ ²⁻, NO₃ ⁻, N₃ ⁻, I⁻, and SCN⁻. Only the three latter nucleophiles substituted the chlorine atom in the 2-CH₂Cl group of kojic acid. In none of the products nucleophilic substitution at position 6 of the 4-pyrone could be found. Regular substituion of chlorokojic acid with I⁻ (iodokojic acid), N₃ ⁻ (azidokojic acid), and SCN⁻ (thiocyanato and isothiocyanato kojic acids) was accompanied by formation of allomaltol. Reaction pathways for the formation of allomaltol and 6-substituted allomaltol derivatives are proposed. The latter has been formerly discovered in the reaction of chlorokojic acid with secondary amines.