Total Synthesis of Zephycarinatines via Photocatalytic Reductive Radical ipso-Cyclization |
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Authors: | Haruka Takeuchi Prof Dr Shinsuke Inuki Kohei Nakagawa Takaaki Kawabe Dr Atsuhiko Ichimura Prof Dr Shinya Oishi Prof Dr Hiroaki Ohno |
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Institution: | Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto, 606-8501 Japan |
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Abstract: | We report herein a nonbiomimetic strategy for the total synthesis of the plicamine-type alkaloids zephycarinatines C and D. The key feature of the synthesis is a stereoselective reductive radical ipso-cyclization using visible-light-mediated photoredox catalysis. This cyclization enabled the construction of a 6,6-spirocyclic core structure through the addition of a carbon-centered radical onto the aromatic ring. Biological evaluation of zephycarinatines and their derivatives revealed that the synthetic derivative with a keto group displays moderate inhibitory activity against LPS-induced NO production. This approach could offer future opportunities to expand the chemical diversity of plicamine-type alkaloids as well as providing useful intermediates for their syntheses. |
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Keywords: | alkaloids natural products photocatalysis radical ipso-cyclization total synthesis |
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