A Bioinspired Synthesis of (±)-Rubrobramide, (±)-Flavipucine, and (±)-Isoflavipucine

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• 作者：Shoma Mizutani ; Kenta Komori ; Prof. Dr. Tohru Taniguchi ; Prof. Dr. Kenji Monde ; Prof. Dr. Kouji Kuramochi and Prof. Dr. Kazunori Tsubaki
• 刊名：Angewandte Chemie
• 出版年：2016
• 出版时间：August 8, 2016
• 年：2016
• 卷：128
• 期：33
• 页码：9705-9708
• 全文大小：1488K
• ISSN：1521-3757

文摘

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.