Metal‐Free Catalytic Access to Indanes via Intermolecular Cyclization from Internal Olefins/Ethers and Mechanism Study

IF 2.5 3区化学 Q2 CHEMISTRY, ORGANIC

European Journal of Organic Chemistry Pub Date : 2025-06-06 DOI:10.1002/ejoc.202500063

Haotian Lv, Yinuo Zhu, Feng Han, Li Guo, Nan Lu, Yuanhong Zhang, Chengxia Miao

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Abstract

A green and sustainable protocol has been developed for metal‐free synthesis of substituted indanes through Brønsted acid‐catalyzed intermolecular cyclization. Employing the acidic ionic liquid [BsPy][OTf] as a catalyst, this methodology achieved good selectivities to synthesize substituted indanes through intermolecular cyclization of benzyl ethers and internal olefins while eliminating metallic reagents, halogens, and post‐reaction neutralization steps. Moreover, the acidity of ionic liquids was one of the significant factors affecting the yield and the selectivity. [BsPy][OTf] exhibited good selectivity and activity, and also had excellent recyclability. Controlling experiments revealed a carbocation‐mediated pathway. DFT calculation indicated that the selectivity of indane as cyclization product is supported by both thermodynamics and kinetics catalyzed by [BsPy][OTf], and the product is determined to be substituted olefin controlled by kinetics using [MeBs(dio)TMP][OTf] as the catalyst. Moreover, the distance of C1⋯C5 to construct the indane ring is shorter and more readily to occur via cyclization path in [BsPy][OTf]‐catalyzed system compared with that of [MeBs(dio)TMP][OTf].

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内链烯烃/醚分子间环化无金属催化制备吲哚及其机理研究

通过Brønsted酸催化的分子间环化，建立了一种绿色、可持续的无金属取代茚烷合成方法。该方法采用酸性离子液体[BsPy][OTf]作为催化剂，通过苯醚和内烯烃的分子间环化合成取代茚，同时省去了金属试剂、卤素和反应后中和步骤，具有良好的选择性。离子液体的酸度是影响收率和选择性的重要因素之一。[BsPy][OTf]表现出良好的选择性和活性，并具有良好的可回收性。对照实验揭示了碳正离子介导的途径。DFT计算表明，[BsPy][OTf]催化的环化产物有一定的热力学和动力学支持，以[MeBs(dio)TMP][OTf]为催化剂的环化产物为动力学控制的取代烯烃。此外，与[MeBs(dio)TMP][OTf]相比，在[BsPy][OTf]‐催化体系中，C1⋯C5构建茚烷环的距离更短，更容易通过环化路径发生。

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来源期刊

European Journal of Organic Chemistry 化学-有机化学

CiteScore

5.40

自引率

3.60%

发文量

752

审稿时长

1 months

期刊介绍： The European Journal of Organic Chemistry (2019 ISI Impact Factor 2.889) publishes Full Papers, Communications, and Minireviews from the entire spectrum of synthetic organic, bioorganic and physical-organic chemistry. It is published on behalf of Chemistry Europe, an association of 16 European chemical societies. The following journals have been merged to form two leading journals, the European Journal of Organic Chemistry and the European Journal of Inorganic Chemistry: Liebigs Annalen Bulletin des Sociétés Chimiques Belges Bulletin de la Société Chimique de France Gazzetta Chimica Italiana Recueil des Travaux Chimiques des Pays-Bas Anales de Química Chimika Chronika Revista Portuguesa de Química ACH—Models in Chemistry Polish Journal of Chemistry.