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Stereochemistry of a Cyclic Epicatechin Trimer with C 3 Symmetry Produced by Oxidative Coupling
Author(s) -
Kawazoe Rina,
Matsuo Yosuke,
Saito Yoshinori,
Tanaka Takashi
Publication year - 2021
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.202001579
Subject(s) - trimer , chemistry , stereochemistry , coupling (piping) , oxidative coupling of methane , crystallography , computational chemistry , organic chemistry , catalysis , dimer , mechanical engineering , engineering
Abstract A cyclic epicatechin trimer with C 3 symmetry, connected through C−C bonds between A‐ and B‐rings, was isolated as an oxidative coupling product of (−)‐epicatechin with polyphenol oxidase. It was previously isolated as an oxidation product of epicatechin with CuCl 2 ; however, only the 2D structure was proposed. Its stereochemistry was assigned using various spectroscopic techniques, including 1D and 2D NMR, and theoretical calculations of the NMR and ECD data. It was suggested that the less strained cyclic trimer with the (a R ,a R ,a R ) configuration was formed atroposelectively in the cyclization process.