Gold(I)‐Catalyzed Dearomative [2+2]‐Cycloaddition of Indoles with Activated Allenes: A Combined Experimental–Computational Study |
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Authors: | Riccardo Ocello Assunta De Nisi Dr. Minqiang Jia Qing‐Qing Yang Prof. Magda Monari Pietro Giacinto Prof. Andrea Bottoni Dr. Gian Pietro Miscione Prof. Marco Bandini |
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Affiliation: | 1. Department of Chemistry “G. Ciamician”, Alma Mater Studiorum ‐ University of Bologna, Via Selmi 2, 40126 Bologna (Italy);2. Department of Chemistry, Fudan University, 220 Handan Road, Shanghai 200433 (China);3. Department of Chemistry, Universidad de los Andes, Carrera 1 N° 18A 10, Bogotá (Colombia) |
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Abstract: | The gold‐catalyzed synthesis of methylidene 2,3‐cyclobutane‐indoles is documented through a combined experimental/computational investigation. Besides optimizing the racemic synthesis of the tricyclic indole compounds, the enantioselective variant is presented to its full extent. In particular, the scope of the reaction encompasses both aryloxyallenes and allenamides as electrophilic partners providing high yields and excellent stereochemical controls in the desired cycloadducts. The computational (DFT) investigation has fully elucidated the reaction mechanism providing clear evidence for a two‐step reaction. Two parallel reaction pathways explain the regioisomeric products obtained under kinetic and thermodynamic conditions. In both cases, the dearomative C?C bond‐forming event turned out to be the rate‐determining step. |
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Keywords: | allenamide asymmetric catalysis density functional calculations gold indole |
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