Hydride Reduction by a Sodium Hydride–Iodide Composite

Sodium hydride (NaH) is widely used as a Brønsted base in chemical synthesis and reacts with various Brønsted 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.     

Mechanistic Insights on Reduction of Carboxamides by Diisobutylaluminum Hydride and Sodium Hydride−Iodide Composite

The reaction mechanisms on reduction of tertiary carboxamides by diisobutylaluminum hydride (DIBAL) and sodium hydride (NaH)‐sodium iodide (NaI) composite were elucidated by the computational and experimental approaches. Reduction of N,N‐dimethyl carboxamides with DIBAL provides the corresponding amines, whereas that with the NaH?NaI composite exclusively forms aldehyde even at high reaction temperature. DFT calculations revealed that dimeric structural nature of DIBAL and Lewis acidity on its Al center play crucial role to decompose the tetrahedral anionic carbinol amine intermediate through C?O bond cleavage. On the other hand, in the reduction with the NaH?NaI composite, the resulting tetrahedral anionic carbinol amine intermediate could be kept stable, thus providing aldehydes as a sole product by the aqueous workup     

Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite

Sodium hydride (NaH) has been commonly used as a Brønsted 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.     

Hydrodehalogenation of Haloarenes by a Sodium Hydride–Iodide Composite

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.     

A Manganese Pre‐Catalyst: Mild Reduction of Amides,Ketones, Aldehydes,and Esters

A new (N ‐phosphinoamidinate)manganese complex is shown to be a useful pre‐catalyst for the hydrosilative reduction of carbonyl compounds, and in most cases at room temperature. The Mn‐catalyzed reduction of tertiary amides to tertiary amines, with a useful scope, is demonstrated for the first time by use of this catalyst, and is competitive with the most effective transition‐metal catalysts known for such transformations. Ketones, aldehydes, and esters were also successfully reduced under mild conditions by using this new Mn catalyst.     

A Novel Route to Synthesize N,N‐Dimethyl Arylmethylamines from Aryl Aldehydes,Hexamethylenetetramine and Hydrogen†

Developing simple and green routes to access valuable chemicals is of significance. Herein, we present a green and novel route to synthesize N,N‐dimethyl arylmethylamines (DAMAs) from hexamethylenetetramine (HMTA) and aryl aldehydes in the presence of hydrogen, and a series of DAMAs can be obtained in good yields. This approach opens the precedent for HMTA as N,N‐dimethylamine source to synthesize chemicals with N,N‐dimethylamine group, which has promising applications for N‐containing chemicals synthesis.     

过渡金属盐促进的纳米氢化钠对硝基的还原反应

研究了在过渡金属盐促进下，纳米尺寸的活性氢化钠对硝基化合物的还原反应．结果表明，过渡金属盐的存在，使纳米氢化钠（ＮａＨ＊）的还原活性进一步增强，硝基苯的转化率在较短时间内就超过９０％．镍盐对生成苯胺的选择性最好（１００％），其次是锰盐．不同纳米碱金属氢化物对硝基苯还原的活性和生成苯胺的选择性顺序为ＮａＨ＊＞ＫＨ＊＞ＬｉＨ＊．几种硝基化合物的反应结果表明，ＮａＨ＊－镍盐是硝基还原生成芳胺有效的复合还原剂     

Preparation of Stable Low‐Oxidation‐State Group 14 Element Amidohydrides and Hydride‐Mediated Ring‐Expansion Chemistry of N‐Heterocyclic Carbenes

Various low oxidation state (+2) group 14 element amidohydride adducts, IPr ? EH(BH₃)NHDipp (E=Si or Ge; IPr=[(HCNDipp)₂C:], Dipp=2,6‐iPr₂C₆H₃), were synthesized. Thermolysis of the reported adducts was investigated as a potential route to Si‐ and Ge‐based clusters; however, unexpected transmetallation chemistry occurred to yield the carbene–borane adduct, IPr ? BH₂NHDipp. When a solution of IPr ? BH₂NHDipp in toluene was heated to 100 °C, a rare C? N bond‐activation/ring‐expansion reaction involving the bound N‐heterocyclic carbene donor (IPr) transpired.     

“离子键”课堂演示实验的改进——碘化钠的简易制备

从教材中钠和氯气反应的演示实验出发,设计独特的实验装置,在实验室里完成了碘化钠的制备。避免了氯气的危害,也满足教学的需要。从热力学角度进行相关计算,证明本实验的可行性。     

Crystallographic report: [N,N‐Methylethylaminopropylalane]2

Dimeric and centrosymmetric [MeEtN(CH₂)₃AlH₂]₂ comprises aluminum centers, coordinated in a distorted trigonal bipyramidal fashion by three hydrogen atoms, one nitrogen atom and one carbon atom. The aluminum atoms are bridged by hydrogen atoms, creating a planar, four‐membered Al₂H₂ ring. Copyright © 2005 John Wiley & Sons, Ltd.     

Iron‐Catalyzed Regioselective Transfer Hydrogenative Couplings of Unactivated Aldehydes with Simple Alkenes

An FeBr₃‐catalyzed reductive coupling of various aldehydes with alkenes that proceeds through a direct hydride transfer pathway has been developed. With ⁱPrOH as the hydrogen donor under mild conditions, previously challenging coupling reactions of unactivated alkyl and aryl aldehydes with simple alkenes, such as styrene derivatives and α‐olefins, proceeded smoothly to furnish a diverse range of functionalized alcohols with complete linear regioselectivity.     

A Well‐Defined Monomeric Aluminum Complex as an Efficient and General Catalyst in the Meerwein–Ponndorf–Verley Reduction

The metal‐catalyzed Meerwein–Ponndorf–Verley (MPV) reduction allows for the mild and sustainable reduction of aldehydes and ketones but has not found widespread application in organic synthesis due to the high catalyst loading often required to obtain satisfactory yields of the reduced product. We report here on the synthesis and structure of a sterically extremely overloaded siloxide‐supported aluminum isopropoxide capable of catalytically reducing a wide range of aldehydes and ketones (52 examples) in excellent yields under mild conditions and with low catalyst loadings. The unseen activity of the developed catalyst system in MPV reductions is due to its unique monomeric nature and the neutral donor isopropanol weakly coordinating to the aluminum center. The present work implies that monomeric aluminum alkoxide catalysts may be attractive alternatives to transition‐metal‐based systems for the selective reduction of aldehydes and ketones to primary and secondary alcohols.     

Oxidative Enantioselective α‐Fluorination of Aliphatic Aldehydes Enabled by N‐Heterocyclic Carbene Catalysis

Described is the first study on oxidative enantioselective α‐fluorination of simple aliphatic aldehydes enabled by N‐heterocyclic carbene catalysis. N‐fluorobis(phenyl)sulfonimide serves as a an oxidant and as an “F” source. The C? F bond formation occurs directly at the α position of simple aliphatic aldehydes, thus overcoming nontrivial challenges, such as competitive difluorination and nonfluorination, and proceeds with high to excellent enantioselectivities.     

Sodium Iodide (NaI)‐Catalyzed Cross‐Coupling for C−S Bond Formation via Oxidative Dehydrogenation: Cheap,Direct Access to Unsymmetrical Aryl Sulfides

A simple and practical NaI‐catalyzed direct C−H sulfenylation of arenes has been developed under air. In this reaction, aryl sulfides were obtained in moderate to excellent yields with high regioselectivity from readily available aromatic compounds and aryl/alkyl thiols, even on gram scale. To demonstrate the practicability of this reaction, two bioactive compound skeletons were synthesized in good yields. This method can also be used to late‐stage modification of curcumin.     

Organic Reactions Using Sodium Hydrogentelluride: Part 4. The Selective Reduction of Aromatic Aldehydes or Ketones with Electron-Withdrawing Groups on the Benzene Ring by Sodium Hydrogentelluride

Aromatic aldehydes or ketones which have electron-withdrawing groups on the benzene ring were selectively reduced to the corresponding alcohols in good yields by sodium hydrogentelluride; common aldehydes such as benzaldehyde and tolualdehyde were inert.