ENANTIOSPECIFIC SYNTHESIS OF 4-O-BENZYL DERIVATIVE OF 3-EPISHIKIMIC ACID FROM D-GLUCOSE

As the configurations of C₂, C₃, C₄ of D-glucose or xylose are in correspondence with C₃, C₄, C₅ Of 3-epishikimic acid, a new enantiospecific synthesis of the benzyl derivative of 3-epishikimie acid from D-glucose has been completed. Thus, D-glucose was converted into 1,2-O-isopropylidene-D-xylofuranose (5) in five steps, Compound 5 was esterificd with trifluoromethanesulphonic anhydride to give 6. The phosphonate(7) was prepared by a two-carbon chain extension of 6 via nucleophilic substitution by sodium salt of trimethylphosphonoacetate in the presence of dibenzo-18-crown-6. Deacetonation of 7 afforded phosphonate (8), or (9) when in the presence of acetic anhydride. Methyl (3S,4S, 5R)4-O-benzyl-3-epishikimate (10) was synthesized from 8 or 9 with methanolic sodium methoxide by an intramolecular Wittig-Horner reaction.