Efficient and versatile synthesis of 5-O-acylquinic acids with a direct esterification using a p-methoxybenzyl quinate as a key intermediate. Issue 20 (20th May 2015)

• Record Type: Journal Article
• Authors: Oyama, Kin-ichi; Watanabe, Noriyuki; Yamada, Tomomi; Suzuki, Masako; Sekiguchi, Yukiko; Kondo, Tadao; Yoshida, Kumi
• Is Part Of: Tetrahedron. Volume 71:Issue 20(2015)
• Page Start: 3120
• Page End: 3130
• Publication Date: 2015-05-20
• Subjects: 5-O-Acylquinic acid -- (−)-Quinic acid -- PMB quinate -- Esterification; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2014.08.064
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: An efficient and versatile synthesis of 5- O -acylquinic acids from commercially available (−)-quinic acid was accomplished. We designed p -methoxybenzyl quinate as a key intermediate, and two problems, the esterification of the sterically hindered 5-OH group for the concise divergent synthesis and the low yield of the final deprotection step, were solved. For the first problem, we improved Tanabe's method, TsCl/NMI-mediated esterification using free carboxylic acids, by the addition of i -Pr2 NEt. For the second problem, we established a TFA- or BCl3 /C6 HMe5 -catalyzed deprotection reaction for the final deprotection step. 5- O -Acylquinic acids were synthesized in seven steps with 45–60% overall yield. Graphical abstract: