A Bioinspired Synthesis of (±)‐Rubrobramide, (±)‐Flavipucine,and (±)‐Isoflavipucine |
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Authors: | Shoma Mizutani Kenta Komori Prof?Dr Tohru Taniguchi Prof?Dr Kenji Monde Prof?Dr Kouji Kuramochi Prof?Dr Kazunori Tsubaki |
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Institution: | 1. Graduate School for Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan;2. Faculty of Advanced Life Science, Frontier Research Center for Post-Genome Science and Technology, Hokkaido University, Sapporo, Japan;3. Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, Chiba, Japan |
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Abstract: | A biomimetic synthesis of naturally occurring lactams rubrobramide, flavipucine, and isoflavipucine is described. The key step is a regioselective Darzens reaction between isobutyl glyoxal and an α‐bromo‐β‐ketoamide. The construction of the core tricyclic ring system of rubrobramide was achieved by a cascade reaction in a single step from an α,β‐epoxy‐γ‐lactam. Furthermore, the absolute configuration of naturally occurring (+)‐rubrobramide was determined by vibrational circular dichroism. (±)‐Flavipucine and (±)‐isoflavipucine were synthesized from an epoxyimide, which was prepared by reaction of isobutyl glyoxal with a protected α‐bromo‐β‐ketoamide. Deprotection of the epoxyimide and formation of the pyridone ring gave (±)‐flavipucine, which was converted into (±)‐isoflavipucine by thermal isomerization. |
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Keywords: | biomimetic synthesis configuration determination lactams total synthesis vibrational spectroscopy |
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