Synthesis of (6S)-6-hydroxy-4-epi-shikimic acid

Abstract

The synthesis of the 6-hydroxylated epimer 7 of shikimic acid from natural shikimic acid 1 is conducted by a sequence of protecting steps, dehydration to the 1,3-cyclohexadiene 4 and photosensitized singlet oxygen cycloaddition reaction. The target molecule is then obtained from the endoperoxide 9 by reduction and deprotection. A new hydroxyl group is thereby inserted into position 6 of shikimic acid whereas the configuration at position 4 is formally inverted.

Stereostructure Reassignment and Determination of the Absolute Configuration of Pericosine Do by a Synthetic Approach

“…Another non-natural regioisomer of pericosine, (-)-16, which was derived from 16a, also showed comparable coupling constants in the same solvent. In addition, the coupling constants for 19 15 and (6S)-6-hydroxy-5epishikimic acid (21) 12 were also similar to those for 8, despite having NMR data recorded in CDCl 3 and methanol-d 4 , respectively. This implies that 19 and 21, which possess the same relative configuration as 8, take similar conformations in different solvents.…”

“…The three remaining diastereomers 8 , 10 , and 11 were potential targets for synthesis. There are few reports of highly functionalized cyclohexenoids possessing such relative configurations as 10 or 11 in natural compounds. − Because we had a sample of precursor 8a from our previous work, 8 was the most accessible molecule. The synthesis of 8 is summarized in Scheme .…”

Facile and Efficient Synthesis of Naturally Occurring Carbasugars (+)-Pericosines A and C

“…Commercially available (−)-quinic acid was converted into methyl ent -3-epiquinate derivative 9 according to a literature method . Alcohol 9 was esterified into triflate 10 , which was eliminated with CsOAc to afford an unstable diene 11 , in 39% isolated yield. Diene 11 was reacted with NBS in a H 2 O/1,4-dioxane solvent system at room temperature to give bromohydrins 12 and 13 in 48% and 20% yields, respectively.…”

Production and Synthetic Modifications of Shikimic Acid

“…Endoperoxide 504 was formed in 94% at 5 °C under a moisture-free oxygen atmosphere, and subsequently reduced with potassium iodide in the presence of acetic acid. Removal of the protecting groups delivered the 6-hydroxy epimer of shikimic acid 506 in 52% overall yield from shikimic acid …”

“…Removal of the protecting groups delivered the 6-hydroxy epimer of shikimic acid 506 in 52% overall yield from shikimic acid. 309 4.2.3. Enzymatic Acylation.…”