Synthesis and properties of 4-diazomethyl-7-methoxycoumarin as a new fluorescent labeling reagent for alcohols and carboxylic acids.

Abstract

4-Diazomethyl-7-methoxycoumarin (DMC) was synthesized as a new fluorescent labeling reagent for hydroxyl and carboxyl compounds for use in high-performance liquid chromatography. Treatment of 4-formyl-7-methoxycoumarin with p-toluenesulfonohydrazide gave the tosylhydrazone in 78% yield, and this was derived to DMC in 78% yield by treatment with 0.2N NaOH. DMC was practically nonfluorescent in solution and possessed excellent storage properties. DMC reacted with alcohols in dichloromethane at room temperature in the presence of HBF4 as a catalyst to give the corresponding fluorescent coumarin ethers and also reacted with carboxylic acids in acetonitrile on heating to give the esters. DMC derivatives of cholestanol and cholesterol were satisfactorily separated by high-performance liquid chromatography. The present studies indicate that DMC is a useful fluorescent reagent for the labeling of alcohols and carboxylic acids.