Abstract: N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-L-α-aspartyl]-S-tert-butyl-L-cysteine-1-methyl ester, a high-potency dipeptide sweetener, is approximately 40 000 times sweeter than sucrose. 3-(3-Hydroxy-4-methoxyphenyl) propanal was synthesized from isovanillin through Wittig reaction, catalytic hydrogenation at room temperature and ambient pressure and reduction with diisobutylaluminium hydride (DIBAL-H). A dipeptide was synthesized from S-tert-butyl-L-cysteine-methyl ester and N-(tert-butoxycarbonyl)-L-aspartic acid-4-tert-butyl ester coupled with 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) and 1-hydroxybenzotriazole (HOBt) by condensation reaction. N-(L-α-aspartyl)-S-tert-butyl-L-cysteine-1-methyl ester was prepared by dissolving the dipeptide in hydrochloric acid (HCl)-dioxane solvent. Finally, 3-(3-hydroxy-4-methoxyphenyl)propanal was reacted with N-(L-α-aspartyl)-S-tert-butyl-L-cysteine-1-methyl ester through palladium on carbon (Pd/C)-catalyzed hydrogenation at room temperature and ambient pressure to obtain N-[N-[3-(3-hydroxy-4-methoxyphenyl)propyl]-L-α-aspartyl]-S-tert-butyl-L-cysteine-1-methyl ester. The structure of the final product was identified by infrared spectroscopy, mass spectrometry and nuclear magnetic resonance.

Key words: high-intensity sweetener, dipeptide, synthesis