LI Yan-bo et al
To synthesis of the novel dipeptide sweetener, using methanol and 3,3-dimethylanrylic acid as starting materials, concentrated sulfuric acid as a catalyst, then through Fischer-Speier esterification to synthesis 3,3-dimethylacrylate, then 2,5-dimethylphenol was treated with 3,3-dimethylacrylate in the presence of methanesulfonic acid to give 4,4,5,8-tetramethyl-3,4-dihydroguccin through Friedel-Crafts acylation.A solution of previous compound added to lithium aluminium hydride to give 3-(2-hydroxy-3,6-dimethylphenyl)-3-methylbutanol, after two steps to protected the alcoholic hydroxyl and phenolic hydroxyl, then acetic acid eliminated the tertbutyldimethylsilyl that could obtain the alcohol which protected by acetyl.The alcohol was oxidation by Dess-Martin periodinane and give the intermediate about neotame derivatives is 3-(2-acetyl-3,6-dimethylphenyl)-3-methylbutyraldehyde.Finally, the intermediate combined with aspartame though Borch reduction by sodium borohydride, the final product N-[N-[3-(2-acetyl-3,6-dimethylphenyl)-3-methylbutyl]-L-α-aspartyl]-L-phenylalanie1-methyl ester was obtained, Using Infrared spectroscopy(IR), ESImass spectrometry(MS)and nuclear magnetic resonance spectroscopy(NMR) for structure identification and characterization, and the final product was a target compound and could reach about 70,000 times higher than sucrose.
