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Synthesis of Ganbajunins D and E and the Proposed Structure of Thelephantin D
Author(s) -
Fujiwara Kenshu,
Kushibe Keisuke,
Sato Takuto,
Norikura Toshio,
Matsue Hajime,
Iwai Kunihisa,
Katoono Ryo,
Suzuki Takanori
Publication year - 2015
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.201500722
Subject(s) - chemistry , isomerization , terphenyl , stereochemistry , chemical shift , structural isomer , chemical structure , nmr spectra database , computational chemistry , organic chemistry , spectral line , catalysis , physics , astronomy
The syntheses of ganbajunins D and E and of the structure proposed for thelephantin D, as well as its regioisomer, were achieved in a divergent manner via a common monoester intermediate. The proposed structure of thelephantin D had NMR chemical shifts different from those of natural thelephantin D. This supported Takahashi's suggestion that the true structure of natural thelephantin D should be the same as that of terrestrin C, as was deduced from the similarities in their NMR spectra. The presence of isomerization equilibria between 2′,5′‐ and 2′,6′‐diacyloxy‐ p ‐terphenyl derivatives in solution, which are the cause of the inseparability of these derivatives, was also demonstrated by monitoring the dynamic transition from a 2′,6′‐diacyloxy‐ p ‐terphenyl‐rich mixture of the derivatives to an equilibrium mixture. The results of biological and chemical property tests – such as cytotoxicity against cancer cells, affinity towards Fe 2+ ion, and antioxidative activity – with the synthesized compounds are also described.