Two non-heme iron enzymes, IsnB and AmbI3, catalyze a novel decarboxylation-assisted olefination to produce indole vinyl isonitrile, an important building block for many natural products. Compared to other reactions catalyzed by this enzyme family, decarboxylation-assisted olefination represents an attractive biosynthetic route and a mechanistically unexplored pathway in constructing a C═C bond. Using mechanistic probes, transient state kinetics, reactive intermediate trapping, spectroscopic characterizations, and product analysis, we propose that both IsnB and AmbI3 initiate stereoselective olefination via a benzylic C–H bond activation by an Fe(IV)–oxo intermediate, and the reaction likely proceeds through a radical- or carbocation-induced decarboxylation to complete C═C bond installation.

中文翻译：

---

两种铁（II）-和2-氧戊二酸依赖性酶催化氧化脱羧的机理研究

两种非血红素铁酶IsnB和AmbI3催化新型的脱羧辅助烯烃化反应，以生产吲哚乙烯基异腈，这是许多天然产物的重要组成部分。与该酶家族催化的其他反应相比，脱羧辅助的烯化反应在构建C═C键方面代表了诱人的生物合成途径和机制未探索的途径。通过使用机械探针，瞬态动力学，反应性中间体捕获，光谱表征和产物分析，我们建议IsnB和AmbI3都通过Fe（IV）-氧代中间体通过苄基C-H键活化来引发立体选择性烯化反应，并进行反应可能通过自由基或碳阳离子诱导的脱羧反应完成C═C键的安装。