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Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron
Published on: August 12, 2019
Spectroscopic Studies of 6-Membered Lipoic Acid Derivative, 1,2,3-Trithiane-4-pentanoic Acid, and Its Characteristic
Seiichi Matsugo1,2, Masaru Kojima1, Yutaka Nakamura1
1Department of Applied Life Sciences, Faculty of Applied Life Sciences, Niigata University of Pharmacy and Medical and Life Sciences, Higashijima 265-1, Akiha, Niigata 956-8603, Japan.
Abstract:
Inserting a sulfur atom into the 1,2-dithiolane ring of lipoic acid (LA racemate) is a promising approach for improving the diversity of lipoic acid (LA racemate). For this purpose, we prepared 1,2,3-trisulfur-lipoic acid derivatives (trisulfur lipoic acid (R-enantiomer, TR-LA, trisulfur lipoamide, racemate TLPA)) by the reaction of R-LA (lipoic acid R-enantiomer) or lipoamide (LPA) and H2S and performed precise stereochemical studies. As a result, the 6-membered-1,2,3-trisulfur ring (TR-LA and TLPA) showed a completely different profile from that of the five-membered dithiolane compounds (R-LA and LPA) in 1H- and 13C-NMR spectroscopy. Raman spectroscopy of TR-LA and TLPA showed a different profile to that of LA and LPA, which also indicates the uniqueness of the 6-membered 1,2,3-trisulfur ring chromophore. The regeneration of lipoic acid from 1,2,3-trisulfur lipoic acid (TR-LA) was achieved using a phosphine derivative and sodium cyanide while maintaining the stereochemistry of the chirality center, with an almost quantitative yield.
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