Efficient and Highly Stereoselective Syntheses of (+)-proto-Quercitol and (−)-gala-Quercitol Starting from the Naturally Abundant (−)-Shikimic Acid

Efficient and highly stereoselective syntheses of (+)-proto-quercitol and (−)-gala-quercitol starting from the naturally abundant (−)-shikimic acid were described in this article. (−)-Shikimic acid was first converted to the key intermediate by eight steps in 53% yield. It was then converted to (+)-proto-quercitol by three steps in 78% yield and was also converted to (−)-gala-quercitol by five steps in 63% yield. In summary, (+)-proto-quercitol and (−)-gala-quercitol were synthesized from (−)-shikimic acid by 11 and 13 steps in 41 and 33% overall yields, respectively.