From 3‑Acyl-2-methylindoles to γ‑Carbolines: Li-Promoted Cycloaddition Reaction and Its Quantum Chemical Study

A one-pot cycloaddition strategy for obtaining γ-carbolines under mild conditions was developed. The reaction represents a new approach to the annulation of a pyridine ring to an indole core. Treating 2-methyl-3-benzoylindoles with lithium diisopropyl amide leads to the elimination of a proton from...

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Bibliographic Details
Published in:Journal of organic chemistry 2019-11, Vol.84 (21), p.13721-13732
Main Authors: Vyalyh, Julia V, Suzdalev, Konstantin F, Lisovin, Anton V, Kletskii, Mikhail E, Burov, Oleg N, Kurbatov, Sergey V
Format: Article
Language:English
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Summary:A one-pot cycloaddition strategy for obtaining γ-carbolines under mild conditions was developed. The reaction represents a new approach to the annulation of a pyridine ring to an indole core. Treating 2-methyl-3-benzoylindoles with lithium diisopropyl amide leads to the elimination of a proton from the 2-methyl group. The organolithium compounds generated were found to react with nitriles. The resulting 4,5-dihydro-1H-pyrido­[4,3-b]­indol-1-ols undergo spontaneous water elimination to give the corresponding γ-carbolines. The applicability of this reaction for the synthesis of isoquinolines has been shown. For the first time, a lithium atom was found to be part of an eight-centered polycyclic transition state according to a detailed DFT PCM/DFT/B3LYP/6-311++G­(d,p) and ab initio PCM/MP2//HF/6-311++G­(d,p) quantum chemical study.
ISSN:0022-3263
1520-6904
DOI:10.1021/acs.joc.9b01926