Zhao P, Huang XX, Song SJ. The hypothesis of tautomeric equilibrium between epimers in ciquitins A and B.
J Asian Nat Prod Res 2022;
24:1052-1057. [PMID:
34871119 DOI:
10.1080/10286020.2021.2009464]
[Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 11/17/2021] [Indexed: 06/13/2023]
Abstract
Recently, ciquitins A and B isolated from the powdered and defatted airdried aerial parts of Leucophyllum ambiguum were reported as a mixture of conformers in a solution at room temperature. Considering the existence of a hemiacetal hydroxyl fragment in the ciquitins A and B, they are more likely to exist in the form of epimer rather than the mixture of conformers. To confirm this hypothesis, the NMR calculations of two epimers at C-9 (1-a and 1-b) were performed and the results matched well with experimental NMR data of mixtures (1). Moreover, a brief discussion on the reason for this hypothesis was also presented.
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