Iron‐Catalyzed Reductive Cyclization by Hydromagnesiation: A Modular Strategy Towards N‐Heterocycles

Abstract

Ar eductive cyclization to prepare av ariety of Nheterocycles,through the use of ortho-vinylanilides,isreported. The reaction is catalyzedb ya ni nexpensive and bench-stable iron complex and generally occurs at ambient temperature. The transformation likely proceeds through hydromagnesiation of the vinyl group,a nd trapping of the in situ generated benzylic anion by an intramolecular electrophile to form the heterocycle.T his iron-catalyzed strategy was shown to be broadly applicable and was utilized in the synthesis of substituted indoles,o xindoles and tetrahydrobenzoazepinoindolone derivatives.M echanistic studies indicated that the reversibility of the hydride transfer step depends on the reactivity of the tethered electrophile.T he synthetic utility of our approachwas further demonstrated by the formal synthesis of ar eported bioactive compound and af amily of natural products.

Iron‐Catalyzed Reductive Cyclization by Hydromagnesiation: A Modular Strategy Towards N‐Heterocycles

“…Thec onnectivity and relative stereochemistry of product 7a were unambiguously confirmed by X-ray diffraction analysis. [28] Thereaction seemingly proceeds through an intramolecular dearomative [29] 1,4-addition of the in situ generated benzylic anion into the indole-3-carboxamide to yield cis-indoline 7.I ti s notable that this iron-catalyzed strategy enables the selective hydromagnesiation across the styrene,u tilizing the a,bunsaturated amide as at erminating electrophile.T his result is in contrast with ap revious report which describes the 1,4conjugate addition of Grignard reagents across related indole scaffolds. [30] Given the unique features and versatility of this ironcatalyzed reductive cyclization, studies to probe the mechanism were undertaken.…”

Iron‐catalyzed intermolecular and intramolecular cyclization reactions of N‐heterocycles

“…According to Loup et al [44] indoles are created through the reductive cyclization of ortho vinyl anilides, catalyzed at room temperature by a stable iron complex. The benzyl carbanion is formed because of the hydromagnesiation of the vinyl ring.…”

Recent Advances in the Synthesis of Fused Heterocyclic Compounds and Their Antitumor Activities

“…Copper catalysis 2018 年, 邓卫平课题组 [37] 同年, 他们课题组 [38] 2018 年, 孔望清课题组 [39] 报道了镍催化 N- ( 2021 年, Lautens 课题组 [40] 报道了铁催化 N-(2-乙烯 2017 年, Chandrasekar 课题组 [42] 发展了邻溴芳胺与 芳基端炔串联环化合成吲哚的反应(Scheme 17a). 该反 应使用一种新型高效的钯-吡啶-氮杂卡宾作为催化剂, 表现出对水氧不敏感和低至 0.1 mol%负载量的优异性 能.…”