Asymmetric synthesis of (−)-4-epi-shikimic acid

The major cycloadduct, arising from the Diels–Alder reaction of maleic anhydride and (1E)-(2′,3′,4′,6′-tetra-O-acetyl-β-d-glucopyranosyloxy)buta-1,3-diene, is converted into methyl 3-O-(β-d-glucopyranosyl)-4-epi-shikimate and into (−)-4-epi-shikimic acid in overall yields of 20 and 17% (based on the diene).