Synthesis of N-acetyl-S-(3-coumarinyl)-cysteine methyl ester and HPLC analysis of urinary coumarin metabolites.

N-Acetyl-S-(3-coumarinyl)cysteine, a metabolite of coumarin in rodents, has been synthesized as methyl ester. A new synthetic route to prepare N-acetyl-S-(3-coumarinyl)-D,L-cysteine methyl ester comprises reaction of 3-mercaptocoumarin with N-acetyl-3-chloro-D,L-alanine methyl ester. N-acetyl-S-(4-coumarinyl)-L-cysteine was obtained by reaction of 3-bromocoumarin and N-acetyl-L-cysteine. A method for the determination of N-acetyl-S-(3-coumarinyl)cysteine as its methyl ester in urine by HPLC has been developed.