Zincate‐Mediated Remote Functionalisation of <i>p</i>‐Iodobenzyl Derivatives Through Metallotropy in 2‐Methyltetrahydrofuran as Key Solvent

Lithium trialkylzincate‐mediated I/Zn exchange reaction has been revisited computationally through a micro‐solvation approach. A never yet investigated iodoaryl derivative bearing a potential bulky para‐directing group, namely 4‐iodobenzyl mesylate, was considered as a substrate. THF as typical solvent and Et3ZnLi have also been considered for the first time in such a reaction. Three mechanistic pathways have been calculated, including (1) a literature‐inspired pathway with full preservation of the synergic character of the reagent as well as a complementary mesylate group‐directed pathway, (2) a THF‐solvated open complex‐promoted pathway and (3) an anionic pathway. While the anionic pathway appeared to be unlikely, pathway involving a THF‐solvated open zincate complex turned out to be the most energetically favoured. Equivalent thermodynamic profiles were found for both complementary pathways with preservation of the synergic character of the reagent, albeit a slight preference could be attributed to that occurring with initial chelation of Li to the mesylate group (OMs) through micro‐solvation approach. The I/Zn exchange was shown to proceed through a lithium‐assisted aryl shuttle‐like process. The iodoaryl substrate is first converted into ArLi intermediate which in turns reacts with the remaining diorganozinc reagent.

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Green Synthesis of 3‐Alkylidenefuran‐2‐ones by Palladium‐Catalyzed Cyclocarbonylation of Aryl Iodides with Benzyl Acetylenes in 2‐MeTHF

Zhan,

Chen,

Wei

et al. 2023

Eur J Org Chem

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A novel, highly efficient heterogeneous palladium‐catalyzed carbonylative cyclization of aryl iodides and benzyl acetylenes has been developed under an atmospheric pressure of CO. The reaction proceeds smoothly in a bioderived solvent 2‐methyltetrahydrofuran (2‐MeTHF) at 50 °C using an MCM‐41‐anchored bidentate phosphine palladium complex [Pd(OAc)2‐MCM‐41‐P,P] as catalyst with DiPEA as base, delivering a wide variety of 3‐alkylidenefuran‐2‐ones in good to excellent yields. The Pd(OAc)2‐MCM‐41‐P,P complex can be easily recovered by a simple centrifugation and recycled more than ten times without any remarkable loss of catalytic activity. The present method not only avoids the use of toxic solvents such as benzene, toluene and THF, but also addresses the key problem of expensive palladium catalyst recovery and recycle, thus preventing palladium contamination in the final product.

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Zincate‐Mediated Remote Functionalisation of p‐Iodobenzyl Derivatives Through Metallotropy in 2‐Methyltetrahydrofuran as Key Solvent

Cited by 3 publications

References 59 publications

Recent Achievements in Organic Reactions in Bio‐based Solvents

Recent Achievements in Organic Reactions in Bio‐based Solvents

The Mechanism of Lithium Zincate‐Mediated I/Zn Exchange Revisited: A Computational Microsolvation Approach in THF**

Green Synthesis of 3‐Alkylidenefuran‐2‐ones by Palladium‐Catalyzed Cyclocarbonylation of Aryl Iodides with Benzyl Acetylenes in 2‐MeTHF

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