The development of synthetic chemistry since the early 1900s owes much to the service of organolithium reagents. Brilliant bases (e.g., deprotonating C–H bonds), nucleophiles (e.g., adding to unsaturated molecules), and transfer agents (e.g., delivering ligands to other metals), these versatile virtuosi and to a lesser extent the organic derivatives of the other common alkali metals sodium and potassium have proved indispensable in both academia and technology. Today these monometallic compounds are still utilized widely in synthetic campaigns, but in recent years they have been joined by an assortment of bimetallic formulations that also contain an alkali metal but in company with another metal. These bimetallic formulations often exhibit unique chemistry that can be interpreted in terms of synergistic effects, for which the alkali metal is essential, though it is often the second metal that performs the synthetic transformation. Here, this “alkali-metal-mediated” chemistry is surveyed focusing mainly on...

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Alkali-Metal-Mediated Synergistic Effects in Polar Main Group Organometallic Chemistry

A simple protocol for hydrodebromination and -deiodination of halo(hetero)arenes was enabled by sodium hydride (NaH) in the presence of lithium iodide (LiI). Mechanistic studies showed that an unusual concerted nucleophilic aromatic substitution operates in the present process.

Hydrodehalogenation of Haloarenes by a Sodium Hydride–Iodide Composite

A method for the nucleophilic amination of methoxy arenes was established by using sodium hydride (NaH) in the presence of lithium iodide (LiI). This method offers an efficient route to benzannulated nitrogen heterocycles. Mechanistic studies showed that the reaction proceeds through an unusual concerted nucleophilic aromatic substitution.

Nucleophilic Amination of Methoxy Arenes Promoted by a Sodium Hydride/Iodide Composite.

Imine-to-amine conversion with catalytic instead of stoichiometric quantities of LiAlH4 is demonstrated (85 °C, catalyst loading≥2.5 mol %, pressure≥1 bar). The effects of temperature, pressure, solvent, and catalyst modifications, as well as the substrate scope are discussed. Experimental investigations and preliminary DFT calculations suggest that the catalytically active species is generated in situ: LiAlH4 +Ph(H)C=NtBu→LiAlH2 [N(tBu)CH2 Ph]2 . A cooperative mechanism in which Li and Al both play a prominent role is proposed.

LiAlH4 : From Stoichiometric Reduction to Imine Hydrogenation Catalysis

Ultra-stable sodium metal-iodine batteries enabled by an in-situ solid electrolyte interphase

Sodium hydride (NaH) is widely used as a Bronsted base in chemical synthesis and reacts with various Bronsted acids, whereas it rarely behaves as a reducing reagent through delivery of the hydride to polar π electrophiles. This study presents a series of reduction reactions of nitriles, amides, and imines as enabled by NaH in the presence of LiI or NaI. This remarkably simple protocol endows NaH with unprecedented and unique hydride-donor chemical reactivity.

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Hydride Reduction by a Sodium Hydride–Iodide Composite

A new protocol for amide-directed ortho and lateral C-H sodiation is enabled by sodium hydride (NaH) in the presence of either sodium iodide (NaI) or lithium iodide (LiI). The transient organosodium intermediates could be transformed into functionalized aromatic compounds.

Amide-Directed C-H Sodiation by a Sodium Hydride/Iodide Composite

Sodium hydride (NaH) has been commonly used as a Bronsted base in chemical syntheses, while it has rarely been employed to add hydride (H(-) ) to unsaturated electrophiles. We previously developed a procedure to activate NaH through the addition of a soluble iodide source and found that the new NaH-NaI composite can effect even stereoselective nucleophilic hydride reductions of nitriles, imines, and carbonyl compounds. In this work, we report that mixing NaH with NaI or LiI in tetrahydrofuran (THF) as a solvent provides a new inorganic composite, which consists of NaI interspersed with activated NaH, as revealed by powder X-ray diffraction, and both solid-state NMR and X-ray photoelectron spectroscopies. DFT calculations imply that this remarkably simple inorganic composite, which is comprised of NaH and NaI, gains nucleophilic hydridic character similar to covalent hydrides, resulting in unprecedented and unique hydride donor chemical reactivity.

https://dr.ntu.edu.sg/bitstream/10356/87665/2/Understanding%20the%20Origins%20of%20Nucleophilic%20Hydride%20Reactivity.pdf

Guo Hao Chan

Papers

Hydride Reduction by a Sodium Hydride–Iodide Composite

Amide-Directed C-H Sodiation by a Sodium Hydride/Iodide Composite

Understanding the origins of nucleophilic hydride reactivity of a sodium hydride-iodide composite

Reduction of N,N-Dimethylcarboxamides to Aldehydes by Sodium Hydride–Iodide Composite

Hydrodecyanation by a Sodium Hydride‐Iodide Composite