Stereodivergent Syntheses of All Stereoisomers of (−)‐Shikimic Acid: Development of a Chiral Pool for the Diverse Polyhydroxy‐cyclohexenoid (or ‐cyclohexanoid) Bioactive Molecules

Abstract

Novel stereodivergent total syntheses of all the seven stereoisomers of (−)‐shikimic acid [(−)‐SA 1] have been systematically performed. (+)‐ent‐SA ent‐1 was synthesized from (−)‐SA 1 via 9 steps in 31 % overall yield; (−)‐3‐epi‐SA 2 was synthesized from (−)‐SA 1 via 5 steps in 66 % overall yield; (+)‐3‐epi‐ent‐SA ent‐2 was synthesized from (−)‐SA 1 via 7 steps in 43 % overall yield; (−)‐4‐epi‐SA 3 was synthesized from (−)‐SA 1 via 11 steps in 32 % overall yield; (+)‐4‐epi‐ent‐SA ent‐3 was synthesized from (−)‐SA 1 via 7 steps in 42 % overall yield; (−)‐5‐epi‐SA 4 was synthesized from (−)‐SA 1 via 6 steps in 56 % overall yield; and (+)‐5‐epi‐ent‐SA ent‐4 was synthesized from (−)‐SA 1 via 12 steps in 29 % overall yield. The stereochemistry of all the above seven stereoisomers of (−)‐SA 1 were further studied by two dimensional (2D) 1H NMR technique.