Synthesis Of Quinic Acid Starting From Shikimic Acid

D-(-)-quinic acid ((1R,3R,4R,5R)-1,3,4,5-tetra-hydroxycyclohexane-l-carboxylic acid) occurs widely in both plants and microorganisms in which it has been recognized as the pivotal biogenetic precursor in the biosynthesis of a variety of aromatic natural products in the biogenetic pathway known as the shikimate pathway. The special structure of quinic acid determines its wide applications as a chiral template in natural product synthesis and as a monomer of new polymer material. Considrering the structural similarity of quinic acid and Shikimic acid, a new route starting from readily available and cheap shikimic acid is designed and carried out in this thesis.The synthetic route is as follows.Ethyl shikimate â…¡-1 was obtained by the esterified of shikimic acid in 97% yield. Ethyl shikimate was acetalized with benzaldehyde, and then bromized with NBS, producing compound â…¡-14 in 90% yield. After quantitative acetylation of C-5 hygroxy, compound â…¡-14 was converted to 11-16 through dihydroxylation catalyzed by RuCl3 in 92% yield. The epoxide â…¡-25 as a key intermediate was prepared by intramolecular SN2 reaction in 75% yield followed by the regioselective expoxy ring opening with PPh3/I2. As a result, we obtained compound â…¡-26 in 79% yield. Eventually a successive hydrogenation and deprotection process yielded the desired quinic acid. Overall, we obtained quinic acid starting from shikimic acid through 10 steps in 40.7% yield.