Well-Defined Amidate-Functionalized N-Heterocyclic Carbene -Supported Rare-Earth Metal Complexes as Catalysts for Efficient Hydroboration of Unactivated Imines and Nitriles

Synthesis and Reactivity of the Rare-Earth Metal Complexes Bearing the Indol-2-yl-Based NCN Pincer Ligand

The pincer rare-earth dialkyl complexes [κ3-LRE(CH2SiMe3)2 (RE = Lu(1a), Yb(1b), Er(1c), Y(1d), Dy(1e))] with the indol-2-yl-based NCN pincer ligand were synthesized by the reactions of the proligand HL (L = 1-Me2NCH2CH2-3-(2-iPrC6H5N═CH)C8H4N) with RE(CH2SiMe3)3(THF)2. These complexes exhibited a variety of reactivities toward organic compounds such as amines, triphenylphosphine ylide, N-phenylimidazole, pyridine derivatives, and o-carborane leading to σ-bond metathesis, migration insertion, and redox reaction products. The reactions of the dialkyl rare-earth metal complexes with o-carborane afforded the novel NCN pincer-ligated carboryne-based metallacyclopropanes which reacted with diphenyl ketone to give insertion products of the RE-C2-ind and one of the RE-Ccage bonds, while the reaction of the carboryne-based metallacyclopropanes with diphenyldiazomethane produced the di-aza-metallacyclopentanes via the insertions of the N═N bond of the diphenyldiazomethane into two RE-Ccage bonds and the RE-C2-ind bond. The reactions of the dialkyl complexes with 2 equiv of 2,2'-bipyridine afforded the pincer-ligated bis(2,2'-bipyridyl monoanionic radical) complexes via the homolytic redox reaction.

Grignard Reagent-Catalyzed Hydroboration of Esters, Nitriles, and Imines

The reduction in esters, nitriles, and imines requires harsh conditions (highly reactive reagents, high temperatures, and pressures) or complex metal-ligand catalytic systems. Catalysts comprising earth-abundant and less toxic elements are desirable from the perspective of green chemistry. In this study, we developed a green hydroboration protocol for the reduction in esters, nitriles, and imines at room temperature (25 °C) using pinacolborane as the reducing agent and a commercially available Grignard reagent as the catalyst. Screening of various alkyl magnesium halides revealed MeMgCl as the optimal catalyst for the reduction. The hydroboration and subsequent hydrolysis of various esters yielded corresponding alcohols over a short reaction time (~0.5 h). The hydroboration of nitriles and imines produced various primary and secondary amines in excellent yields. Chemoselective reduction and density functional theory calculations are also performed. The proposed green hydroboration protocol eliminates the requirements for complex ligand systems and elevated temperatures, providing an effective method for the reduction in esters, nitriles, and imines at room temperature.

Synthetic Strategies of N-Heterocyclic Olefin (NHOs) and Their Recent Application of Organocatalytic Reactions and Beyond

N-heterocyclic olefin (NHO) derivatives have an electron-rich as well as highly polarized carabon-carbon (C=C) double bond because of the electron-donating nature of nitrogen and sulphur atoms. While NHOs have been developing as novel organocatalysts and ligands for transition-metal complexes in various organic compound syntheses, different research groups are currently interested in preparing imidazole and triazolium-based chiral NHO catalysts. Some of them have been used for enantioselective organic transformations, but were still elusive. N-heterocyclic olefins, the alkylidene derivatives of N-heterocyclic carbenes (NHC), have shown promising results as effective promoters for numerous organic syntheses such as asymmetric catalysis, hydroborylation, hydrosilylation, reduction, CO2 sequestration, alkylation, cycloaddition, polymerization and the ring-opening reaction of aziridine and epoxides, esterification, C-F bond functionalization, amine coupling, trifluoromethyl thiolation, amination etc. NHOs catalysts with suitable structures can serve as a novel class of Lewis/Bronsted bases with strong basicity and high nucleophilicity properties.These facts strongly suggest their enormous chemical potential as sustainable catalysts for a wide variety of reactions in synthetic chemistry. The synthesis of NHOs and their properties are briefly reviewed in this article, along with a summary of the imidazole and triazole core of NHOs' most recent catalytic uses.

Room Temperature Reduction of Titanium Tetrachloride-Activated Nitriles to Primary Amines with Ammonia-Borane

The reduction of a variety of aromatic and aliphatic nitriles, activated by a molar equivalent of titanium tetrachloride, has been achieved at room temperature using ammonia borane as a safe reductant. The corresponding methanamines were isolated in good to excellent yields following a simple acid-base workup.

Comparing B-H Bond Activation in NiIIX(NNN)-Catalyzed Nitrile Dihydroboration (X = Anionic N-, C-, O-, S-, or P-donor)

One of the key steps in many metal complex-catalyzed hydroboration reactions is B-H bond activation, which results in metal hydride formation. Anionic ligands that include multiple lone pairs of electrons, in cooperation with a metal center, have notable potential in redox-neutral B-H bond activation through metal-ligand cooperation. Herein, using an easily prepared N_pyridineN_imineN_pyrrolide ligand (L²)^-, a series of divalent Ni^IIX(NNN) complexes were synthesized, with X = bromide (2), phenoxide (3), thiophenoxide (4), 2,5-dimethylpyrrolide (5), diphenylphosphide (6), and phenyl (7). The complexes were characterized using ¹H and ¹³C NMR spectroscopy, mass spectrometry, and X-ray crystallography and employed as precatalysts for nitrile dihydroboration. Superior activity of the phenoxy derivative (3) [vs thiophenoxy (4) or phenyl (7)] suggests that B-H bond activation occurs at the Ni-X (vs ligand Ni-N_pyrrolide) bond. Furthermore, stoichiometric treatment of 2-7 with a nitrile showed no reaction, whereas stoichiometric reactions of 2-7 with pinacolborane (HBpin) gave the same Ni-H complex for 2, 3, and 5. Considering that only 2, 3, and 5 successfully catalyzed nitrile dihydroboration, we suggest that the catalytic cycle involves a conventional inner sphere pathway initiated by substrate insertion into Ni-H.

A Boron-Nitrogen Double Transborylation Strategy for Borane-Catalyzed Hydroboration of Nitriles

Organoborane-catalyzed hydroboration of nitriles provides N,N-diborylamines, which act as efficient synthons for the synthesis of primary amines and secondary amides. Known nitrile hydroboration methods are dominated by metal catalysis. Simple and metal-free hydroboration of nitriles using diborane [H-B-9-BBN]₂ as a catalyst and pinacolborane as a turnover reagent is reported. The reaction of monomeric H-B-9-BBN with nitriles leads to the hydrido-bridged diborylimine intermediate; a subsequent sequential double hydroboration-transborylation pathway involving B-N/B-H σ bond metathesis is proposed.

Phosphine-catalyzed hydroboration of propiolonitriles: access to (E)-1,2-vinylcyanotrifluoroborate derivatives

We report an organocatalytic trans hydroboration of 3-substituted-propiolonitriles. In the presence of catalytic amounts of tributylphosphine and pinacolborane, regioselective hydroboration of the internal triple bond proceeded in a stereoselective fashion under mild conditions to afford the corresponding (E)-1,2-vinylcyanoborane derivatives. The mechanism is proposed to occur through a 1,2-phosphine addition instead of a canonical 1,4-conjugate addition pathway.

Applications of catalysis in hydroboration of imines, nitriles, and carbodiimides

The catalytic hydroboration of imines, nitriles, and carbodiimides is a powerful method of preparing amines which are key synthetic intermediates in the synthesis of many value-added products. Imine hydroboration has perennially featured in notable reports while nitrile and carbodiimide hydroboration have gained attention recently. Initial developments in catalytic hydroboration of imines and nitriles employed precious metals and typically required harsh reaction conditions. More recent advances have shifted toward the use of base metal and main group element catalysis and milder reaction conditions. In this survey, we review metal and nonmetal catalyzed hydroboration of these unsaturated organic molecules and group them into three distinct categories: precious metals, base metals, and main group catalysts. The TON and TOF of imine hydroboration catalysts are reported and summarized with a brief overview of recent advances in the field. Mechanistic and kinetic studies of some of these protocols are also presented.

s-Block Metal Catalysts for the Hydroboration of Unsaturated Bonds

The addition of a B-H bond to an unsaturated bond (polarized or unpolarized) is a powerful and atom-economic tool for the synthesis of organoboranes. In recent years, s-block organometallics have appeared as alternative catalysts to transition-metal complexes, which traditionally catalyze the hydroboration of unsaturated bonds. Because of the recent and rapid development in the field of hydroboration of unsaturated bonds catalyzed by alkali (Li, Na, K) and alkaline earth (Mg, Ca, Sr, Ba) metals, we provide a detailed and updated comprehensive review that covers the synthesis, reactivity, and application of s-block metal catalysts in the hydroboration of polarized as well as unsaturated carbon-carbon bonds. Moreover, we describe the main reaction mechanisms, providing valuable insight into the reactivity of the s-block metal catalysts. Finally, we compare these s-block metal complexes with other redox-neutral catalytic systems based on p-block metals including aluminum complexes and f-block metal complexes of lanthanides and early actinides. In this review, we aim to provide a comprehensive, authoritative, and critical assessment of the state of the art within this highly interesting research area.

Bicyclic (alkyl)(amino)carbene (BICAAC) as a metal-free catalyst for reduction of nitriles to amines

Bicyclic (alkyl)(amino)carbene (BICAAC) is introduced as a metal-free catalyst for the reduction of various nitriles to the corresponding amine hydrochloride salts in the presence of pinacolborane. Mechanistic investigations combining experiments and DFT calculations suggest a B-H addition to the carbene center, which acts as a carrier of the hydride source.

Mechanistic Insight into Hydroboration of Imines from Combined Computational and Experimental Studies

Boron Lewis acid-catalyzed and catalyst-free hydroboration reactions of imines are attractive due to the mild reaction conditions. In this work, the mechanistic details of the hydroboration reactions of two different kinds of imines with pinacolborane (HBpin) are investigated by combining density functional theory calculations and some experimental studies. For the hydroboration reaction of N-(α-methylbenzylidene)aniline catalyzed by tris[3,5-bis(trifluoromethyl)phenyl]borane (BAr^F ₃ ), our calculations show that the reaction proceeds through a boron Lewis acid-promoted hydride transfer mechanism rather than the classical Lewis acid activation mechanism. For the catalyst- and solvent-free hydroboration reaction of imine, N-benzylideneaniline, our calculations and experimental studies indicate that this reaction is difficult to occur under the reaction conditions reported previously. With a combination of computational and experimental studies, we have established that the commercially available BH₃  ⋅ SMe₂ can serve as an efficient catalyst for the hydroboration reactions of N-benzylideneaniline and similar imines. The hydroboration reactions catalyzed by BH₃  ⋅ SMe₂ are most likely to proceed through a hydroboration/B-H/B-N σ-bond metathesis pathway, which is very different from that of the reaction catalyzed by BAr^F ₃ .

Late Lanthanide Macrocyclic Tetra-NHC Complexes

An isostructural set of macrocyclic tetra-N-heterocyclic carbene (NHC) complexes were synthesized on late lanthanides including Lu, Yb, Ho, Dy, and Gd. They were characterized by single-crystal X-ray diffraction, multinuclear NMR, electrochemistry, and SQUID magnetometry. Solid-state structures show that all complexes are in a highly distorted square-pyramidal geometry with an axial HMDS ligand. ¹H NMR for Lu, Yb, and Dy demonstrates that these geometries are maintained in solution. Electrochemical measurements on the Yb complex show that the NHCs are very strong σ-donors compared to other organometallic Yb complexes. Magnetic measurements of the Yb and Dy complexes reveal slow relaxation of the magnetization in both complexes. The highly anisotropic Dy complex possesses an energy barrier to spin reversal of 52.42 K/36.43 cm^-1 and waist-restricted hysteresis up to 2.8 K. Finally, an 18-atom macrocycle variant of the Lu complex was synthesized for comparison in reactivity and stability. These complexes are the first lanthanides prepared with macrocyclic NHCs and suggest that NHCs may be a promising ligand for developing single-molecule magnets.

Synthesis and characterization of rare-earth metallate amido complexes bearing 2-amidate-functionalized indolyl ligand and their application in the hydroboration of esters with pinacolborane

The reactions of 2-amidate-functionalized indolyl proligand 2-(2,6-iPr2C6H3NHC=O)C8H5NH (H2L) with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 were studied leading to the synthesis and characterization of a series of novel discrete trinuclear rare-earth metal metallate amido complexes...

Transformation of the sp2 Carbanion to Carbene with Subsequent 1,1-Migratory Insertion and Nucleophilic Substitution in Rare-Earth Metal Chemistry

The development of Fischer-type electrophilic carbene chemistry with early transition metals has been a great challenge due to the fact that such metals in their high oxidation states lack the d electrons to stabilize the electrophilic carbene. Herein, we disclose the first experimental and theoretical findings of in situ transformation of an sp² carbanion to a Fischer-type electrophilic carbene with rare-earth metals in their high oxidation state with a d⁰ electron via electron transfer. The carbene may undergo 1,1-migratory insertion into an adjacent RE-C(sp³) bond, and an unprecedented ring opening of the indole ring of the ligand occurs when the carbenes undergo nucleophilic substitution with a special organolithium reagent o-Me₂NC₆H₄CH₂Li. The key to success is the uniquely tailored novel ligand systems featuring a suitable conjugate building block (^-C═C-C═N) bearing an sp² carbanion connected to the rare-earth metal center.

Automated prediction of lattice parameters from X-ray powder diffraction patterns

A key step in the analysis of powder X-ray diffraction (PXRD) data is the accurate determination of unit-cell lattice parameters. This step often requires significant human intervention and is a bottleneck that hinders efforts towards automated analysis. This work develops a series of one-dimensional convolutional neural networks (1D-CNNs) trained to provide lattice parameter estimates for each crystal system. A mean absolute percentage error of approximately 10% is achieved for each crystal system, which corresponds to a 100- to 1000-fold reduction in lattice parameter search space volume. The models learn from nearly one million crystal structures contained within the Inorganic Crystal Structure Database and the Cambridge Structural Database and, due to the nature of these two complimentary databases, the models generalize well across chemistries. A key component of this work is a systematic analysis of the effect of different realistic experimental non-idealities on model performance. It is found that the addition of impurity phases, baseline noise and peak broadening present the greatest challenges to learning, while zero-offset error and random intensity modulations have little effect. However, appropriate data modification schemes can be used to bolster model performance and yield reasonable predictions, even for data which simulate realistic experimental non-idealities. In order to obtain accurate results, a new approach is introduced which uses the initial machine learning estimates with existing iterative whole-pattern refinement schemes to tackle automated unit-cell solution.

Water-soluble silver(i) complexes with N-donor benzimidazole ligands containing an imidazolium core: stability and preliminary biological studies

Herein, we report the synthesis, characterisation and preliminary biological evaluation of two novel silver(i) complexes of type [AgL₂](NO₃)₃ (3 and 4) with ionic N-donor benzimidazoles. The complexes have been synthesized by the reaction of 1.5 equivalents of silver nitrate and N-donor benzimidazoles containing an imidazolium core at the 2-position (1 and 2) in ethanol. The X-ray analysis of 4 shows that it has two free imidazolium cores and the charge is balanced with three nitrate anions. A study by the combination of NMR, IR, LC-MS and elemental analysis techniques also suggests that the complexes have this structure both in the solid-state and solution. The complexes are highly soluble and stable in water. Cytotoxicity evaluation against four cancerous human cells and one non-cancerous human cell revealed that the complexes have no significant anti-growth effect. However, the complexes showed a remarkable antimicrobial effect at normalized minimum inhibitory concentrations (normalized MICs) in the range of 33-268 μM against a panel of microorganisms consisting of Gram-negative and Gram-positive bacteria, and fungi.

Aluminum Amidinates: Insights into Alkyne Hydroboration

The mechanism of the aluminum-mediated hydroboration of terminal alkynes was investigated using a series of novel aluminum amidinate hydride and alkyl complexes bearing symmetric and asymmetric ligands. The new aluminum complexes were fully characterized and found to facilitate the formation of the (E)-vinylboronate hydroboration product, with rates and orders of reaction linked to complex size and stability. Kinetic analysis and stoichiometric reactions were used to elucidate the mechanism, which we propose to proceed via the initial formation of an Al-borane adduct. Additionally, the most unstable complex was found to promote decomposition of the pinacolborane substrate to borane (BH3), which can then proceed to catalyze the reaction. This mechanism is in contrast to previously reported aluminum hydride-catalyzed hydroboration reactions, which are proposed to proceed via the initial formation of an aluminum acetylide, or by hydroalumination to form a vinylboronate ester as the first step in the catalytic cycle.

Iron-catalysed hydroboration of non-activated imines and nitriles: kinetic and mechanistic studies

Iron-catalysed hydroboration of imines and nitriles has been developed under low catalyst loading (1 mol%) in the presence of HBpin. A wide scope of substrate was found to smoothly undergo hydroboration, including electron releasing/withdrawing and halogen substitution patterns and cyclic substrates which all afforded the corresponding amines in good to excellent yields. Dihydroboration of nitriles was achieved conveniently under solvent free and additive free conditions. Promisingly, this catalytic system is also capable of the hydroboration of challenging ketimine substrates. Preliminary kinetic analysis of imine hydroboration reveals a first-order dependence on catalyst concentration. Both HBpin and 4-fluorophenyl-N-phenylmethanimine (1b) appear to exhibit saturation kinetics with first order dependence up to 0.5 mmol HBpin and 0.75 mmol imine, respectively. Temperature-dependent rate experiments for imine hydroboration have also been explored. Activation parameters for the hydroboration of FPhC[double bond, length as m-dash]NPh (1b) were determined from the Eyring and Arrhenius plots with ΔS ≠, ΔH ≠, and E a values of -28.69 (±0.3) e.u., 12.95 (±0.04) kcal mol-1, and 15.22 (±0.09) kcal mol-1, respectively.

An Unsymmetric Imino-Phosphanamidinate Ligand and its Y(III) Complex: Synthesis, Characterization, and Catalytic Hydroboration of Carbonyl Compounds

An imino-phosphanamide ligand, [NHI^iPr2Me2P(Ph)NH-2,6-ⁱPr₂C₆H₃] (LH), containing two different N-substituents was prepared by the direct reaction of the lithium salt of N-heterocyclic imine (NHI) with phenylchloro-2,6-diisopropylphenyl phosphanamine, PhP(Cl)NH-2,6-ⁱPr₂-C₆H₃. Reaction of LH with Y(N(SiMe₃)₂)₃ afforded the heteroleptic complex, [{L}Y(N(SiMe₃)₂)₂] (1), by elimination of HN(SiMe₃)₂. Compound 1 was characterized by multinuclear NMR and X-ray crystallography. In the complex, the Y(III) center was found to be tetracoordinate in a distorted tetrahedral geometry. The ligand, imino-phosphanamidinate, [L]^-, functions in a chelating manner, and its coordination to Y(III) results in a distorted 4-membered YPN₂ ring. As a proof of principle of its activity, 1 was used as a precatalyst for the hydroboration of various aldehydes and ketones using HBpin as the hydrogen source. The hydroboration reaction was rapid and clean even with low catalyst loadings (0.01-0.1 mol %). In addition, a very good functional group tolerance was observed in these reactions.

O,N-Heterocyclic germylenes as efficient catalysts for hydroboration and cyanosilylation of benzaldehyde

Novel O,N-heterocyclic germylenes were examined as catalysts for cyanosilylation and hydroboration of benzaldehyde.

The hydroboration of α-diimines

The uncatalyzed addition of catecholborane to α-diimines has been examined.

Hydroboration of nitriles and imines by highly active zinc dihydride catalysts

Eco-friendly zinc dihydrides stabilized by N-heterocyclic carbenes were demonstrated to be highly efficient catalysts for the double hydroboration of nitriles with pinacolborane, exhibiting turnover frequencies up to 3000 h⁻¹ at room temperature under solvent-free conditions. The reactions afforded corresponding diboronated amines with excellent yields and good functional group tolerance. A single Zn–H insertion product was isolated from a stoichiometric reaction of zinc dihydride with nitrile, and was proved to be an active species in this transformation. Kinetic studies were performed to give some insights into the catalytic reactions. In addition, zinc dihydride species also showed high activity for the hydroboration of imines to boronated amines.

Molecular zinc dihydrides were found to be highly efficient catalysts for the hydroboration of nitriles and imines at room temperature under solvent-free conditions.

Samarium(iii) catalyzed synthesis of alkenylboron compounds via hydroboration of alkynes

The homoleptic lanthanide complex Sm[N(TMS)₂]₃ is an efficient rare-earth catalyst for the hydroboration of alkynes to the corresponding alkenylboron compounds.

Catalytic Nitrile Hydroboration: A Route to N,N-Diborylamines and Uses Thereof

Catalytic reduction of nitriles is considered as an attractive and atom-economical route to a diversity of synthetically valuable primary amines. Compared to other methods, dihydroboration approach has been developed relatively recently but has already attracted the attention of many research groups due to reasonably mild reaction conditions, selectivity control and the access to N,N-diborylamines, which emerged as powerful reagents for C-N bond forming reactions. Early developments in catalytic dihydroboration of nitriles implied precious metal catalysts along with harsh conditions and prolonged reaction times, whereas recent advances mostly rely on base and main group metal catalytic systems with significantly improved profiles. This minireview aims to provide an overview of advances and challenges of dihydroboration of nitriles with d-, f- and main group metal catalysts. Mechanistic features of different catalytic systems, functional group tolerance and scope of the methods are also presented. The synthetic utility of N,N-diborylamies, beyond simple protodeborylation, is discussed in the aspect of N-arylation, imine and amide synthesis.

Efficient Co-Catalyzed Double Hydroboration of Nitriles: Application to One-Pot Conversion of Nitriles to Aldimines

The commercially available and bench-stable Co(acac)₂ /dpephos system is employed as a precatalyst for selective and efficient room temperature hydroboration of organic nitriles with HBPin to produce a series of N,N-diborylamines [RN(BPin)₂ ], which react in situ with aldehydes to give aldimines. Formation of aldimines from N,N-diborylamines does not require a dehydrating agent, is applicable to a wide range of N,N-diborylamine and aldehyde substrates and is highly chemoselective, being unaffected by various common functional groups, such as alkenes, alkynes, secondary amines, ketones, esters, amides, carboxylic acids, pyridines, nitriles, and nitro compounds. The overall transformation represents a synthetically valuable approach to aldimines from nitriles and can be performed in a sequential one-pot manner, tolerating ester, lactone, carboxamide and unactivated alkene functionalities.

Homoleptic Bis(trimethylsilyl)amides of Yttrium Complexes Catalyzed Hydroboration Reduction of Amides to Amines

Homoleptic lanthanide complex Y[N(TMS)₂]₃ is an efficient homogeneous catalyst for the hydroboration reduction of secondary amides and tertiary amides to corresponding amines. A series of amides containing different functional groups such as cyano, nitro, and vinyl groups were found to be well-tolerated. This transformation has also been nicely applied to the synthesis of indoles and piribedil. Detailed isotopic labeling experiments, control experiments, and kinetic studies provided cumulative evidence to elucidate the reaction mechanism.

Lithium bromide: an inexpensive and efficient catalyst for imine hydroboration with pinacolborane at room temperature

An efficient protocol for the hydroboration of imines is reported. Lithium halide salts are effective catalysts to convert aldimines and ketimines to their corresponding amines. Here, we report excellent isolated yield of secondary amines (>95%) using 3 mol% lithium bromide in THF at room temperature. In addition, DFT calculations for a plausible reaction pathway are reported.

An efficient protocol for the hydroboration of imines using LiBr is reported.

Lithium amide catalyzed hydroboration of nitriles

An operationally facile hydroboration of nitriles is reported that utilizes the stable and inexpensive catalyst LiN(SiMe₃)₂. The reaction displayed good tolerance of functional groups and also converted carbonyl derivatives.

Quantitative NaH catalytic hydroboration of aldimines

The catalytic hydroboration of aldimines was demonstrated, with only 3 mol% NaH required for the quantitative production of secondary amines under minimal solvent conditions.

Scope and mechanism of nitrile dihydroboration mediated by a β-diketiminate manganese hydride catalyst

Nitrile insertion allows for manganese-catalyzed nitrile dihydroboration at 80 °C.

Asymmetric ketone hydroboration catalyzed by alkali metal complexes derived from BINOL ligands

The ability of alkali metal complexes featuring functionalized BINOL-derived ligands to catalyze ketone hydroboration reactions was explored. The reduced products were formed in excellent yields and with variable enantioselectivities dependent upon the nature of the ligand and the alkali metal cation.

Catalytic Hydroboration of Aldehydes, Ketones, and Alkenes Using Potassium Carbonate: A Small Key to Big Transformation

An efficient transition-metal-free protocol for the hydroboration of aldehydes and ketones (reduction) was developed. The hydroboration of a wide range of aldehydes and ketones with pinacolborane (HBpin) under the K₂CO₃ catalyst has been studied. The reaction system is practical and reliable and proceeds under extremely mild and operationally simple conditions. No prior preparation of the complex metal catalyst was required, and hydroboration occurred stoichiometrically. Further, the chemoselective reduction of aldehydes over ketones was carried out. Moreover, we demonstrated the use of K₂CO₃ as an efficient catalyst for the hydroboration of alkenes. The operational simplicity, inexpensive and transition-metal-free catalyst, and the applicability to gram-scale synthesis strengthen its potential applications for hydroboration (reduction) at an industrial scale.