Organoboron chemistry

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Organoboron OrganoboronLogo.svg
Organoboron

Organoboron chemistry or organoborane chemistry studies organoboron compounds, also called organoboranes. These chemical compounds combine boron and carbon; typically, they are organic derivatives of borane (BH3), as in the trialkyl boranes. [1] [2]

Contents

Organoboranes and -borates enable many chemical transformations in organic chemistry — most importantly, hydroboration and carboboration. Most reactions transfer a nucleophilic boron substituent to an electrophilic center either inter- or intramolecularly. In particular, α,β-unsaturated borates and borates with an α leaving group are highly susceptible to intramolecular 1,2-migration of a group from boron to the electrophilic α position. Oxidation or protonolysis of the resulting organoboranes generates many organic products, including alcohols, carbonyl compounds, alkenes, and halides. [3]

Properties of the B-C bond

The C-B bond has low polarity (electronegativity 2.55 for carbon and 2.04 for boron). Alkyl boron compounds are in general stable, though easily oxidized.

Boron often forms electron-deficient compounds without a full octet, such as the triorganoboranes. These compounds are strong electrophiles, but typically too sterically hindered to dimerize. Electron donation from vinyl and aryl groups can lend the C-B bond some double bond character.

Classes of organoboron compounds

Organoboranes and hydrides

Structure of a rare monomeric boron hydride, R = i-Pr. Ar2BHmonomer.svg
Structure of a rare monomeric boron hydride, R = i-Pr.

The most-studied class of organoboron compounds has the formula BRnH3−n. These compounds are catalysts, reagents, and synthetic intermediates. The trialkyl and triaryl derivatives feature a trigonal-planar boron center that is typically only weakly Lewis acidic. Except a few bulky derivatives, the hydrides (n = 1 or 2) dimerize, like diborane itself. Trisubstituted derivatives, e.g. triethylboron, are monomers. [5]

Borinic and boronic acids and esters (BRn(OR)3-n)

Compounds of the type BRn(OR)3-n are called borinic esters (n = 2), boronic esters (n = 1), and borates (n = 0). Boronic acids are key to the Suzuki reaction. Trimethyl borate, debatably not an organoboron compound, is an intermediate in sodium borohydride production.

Boron clusters

Boron is renowned for cluster species, e.g. dodecaborate [B12H12]2-. Such clusters have many organic derivatives. One example is [B12(CH3)12]2- and its radical derivative [B12(CH3)12]−. [6] Related cluster compounds with carbon vertices are carboranes; the best known is orthocarborane, C2B10H12. Carboranes have few commercial applications. Anionic derivatives such as [C2B9H11]2−, called dicarbollides, ligate similarly to cyclopentadienide.

Bora-substituted aromatic compounds

In borabenzene, boron replaces one CH center in benzene. Borabenzene and derivatives invariably appear as adducts, e.g., C5H5B-pyridine.

The cyclic compound borole, a structural analog of pyrrole, has not been isolated, but substituted derivatives (boroles) are known.

The cyclic compound borepin is aromatic.

Boryl compounds

Organometallic compounds with metal-boron bonds (M–BR2) are boryl complexes, corresponding to the notional boryl anion R2B−. Related ligands are borylenes (M–B(R)–M).

Strong bases do not deprotonate boranes R2BH. Instead these reactions afford the octet-complete adduct R2HB-base. [7]

Compounds isoelectronic with the N-heterocyclic carbenes are known The unusual compound was prepared by reduction of a boron-bromide precursor: [8] [9]

Boryllithium.png

Alkylideneboranes

Alkylideneboranes (RB=CRR) with a boron–carbon double bond are rare. One example is borabenzene. The parent compound, HB=CH2, can be detected at low temperature. The derivative CH3B=C(SiMe3)2 is fairly stable, but prone to cyclodimerisation. [10]

NHC adducts of boron

NHCs and boranes form stable NHC-boraneadducts. [11] Triethylborane adducts can be synthesised directly from the imidazolium salt and lithium triethylborohydride.

Diborenes

Boron-boron double bonds are extraordinarily rare. In 2007, the University of Georgia's Gregory Robinson presented the first neutral diborene (RHB=BHR): [12] [13]

DiboreneSynthesis.png

Each boron atom has an attached proton and is coordinated to a NHC carbene. The parent structure with the additional carbene ligands is diborane(2). [14] [15]

A reported diboryne is based on similar chemistry.

Synthesis

From Grignard reagents

Simple organoboranes such as triethylborane or tris(pentafluorophenyl)boron can be prepared from trifluoroborane (in ether) and the ethyl or pentafluorophenyl Grignard reagent. Further carbanion addition will effect a borate (R4B−).

Boronic acids RB(OH)2 react with potassium bifluoride K[HF2] to form trifluoroborate salts K[RBF3], [16] precursors to nucleophilic alkyl and aryl boron difluorides, ArBF2: [17]

AlkyltrifluoroboratesBatey2002.svg

From alkenes

In hydroboration, alkenes insert into borane B-H bonds, with anti-Markovnikov stereochemistry. Hydroboration occurs stereospecifically syn — on the same alkene face. The transition state for this concerted reaction can be visualized as a square with the corners occupied by carbon, carbon, hydrogen and boron, maximizing overlap between the olefin p-orbitals and the empty boron orbital.

Hydroboration with borane (BH3) equivalents converts only 33% of the starting olefin to product — boron-containing byproducts consume the remainder. The chelate effect improves that ratio for cyclic boron-containing reagents. One common cyclic organoboron reagent is 9-BBN. [18] [19]

By borylation

Metal-catalyzed borylation reactions produce an organoboron compound from aliphatic or aromatic C-H sigma bonds via a transition-metal catalyst. A common reagent is bis(pinacolato)diboron.

From other boron compounds

Carbon monoxide reacts with alkylboranes to form an unstable borane carbonyl. Then an alkyl substituent migrates from boron to the carbonyl carbon. For example, homologated primary alcohols result from organoboranes, carbon monoxide, and a reducing agent (here, sodium borohydride): [20]

BoronScopeCarb.png

Alkenylboranes

Alkynylboranes attack electrophiles to give trans alkenylboranes, [21] as in the first step of this olefin synthesis:

BoronMech3.png

Reactions

Overall synthetic routes via organoboron compounds BoronGen.png
Overall synthetic routes via organoboron compounds

The key property of organoboranes (R3B) and borates (R4B−, generated via addition of R− to R3B) is their susceptibility to reorganization. These compounds possess boron–carbon bonds polarized toward carbon. The boron-attached carbon is nucleophilic; [22] in borates, the nucleophicity suffices for intermolecular transfer to an electrophile. [23] [3]

Boranes alone are generally not nucleophilic enough to transfer an R group intermolecularly. Instead, the group 1,2-migrates to an electrophilic carbon attached to boron, especially if that carbon is unsaturated or bears a good leaving group: [23]

BoronMech1.png

An organic group's migration propensity depends on its ability to stabilize negative charge: alkynyl > aryl ≈ alkenyl > primary alkyl > secondary alkyl > tertiary alkyl. [24] Bis(norbornyl)borane and 9-BBN are often hydroboration reagents for this reason — only the hydroborated olefin is likely to migrate upon nucleophilic activation.

Migration retains configuration at the migrant carbon [25] and inverts it at the (presumably sp3-hybridized) terminus. [26] The resulting reorganized borane can then be oxidized or protolyzed to a final product.

Protonolysis

Organoboranes are unstable to Brønsted–Lowry acids, deboronating in favor of a proton. Consequently, organoboranes are easily removed from an alkane or alkene substrate, as in the second step of this olefin synthesis: [21]

BoronMech3.png

Addition to halocarbonyls

α-Halo enolates are common nucleophiles in borane reorganization. After nucleophilic attack at boron, the resulting ketoboronate eliminates the halogen and tautomerizes to a neutral enolborane. A functionalized carbonyl compound then results from protonolysis, [27] or quenching with other electrophiles:

BoronMech2.png

Because the migration is stereospecific, this method synthesizes enantiopure α-alkyl or -aryl ketones. [28]

α-Haloester enolates add similarly to boranes, but with lower yields: [29]

BoronScope3.png
BoronScope4.png

Diazoesters and diazoketones remove the requirement for external base. [30] α,α'-Dihalo enolates react with boranes to form α-halo carbonyl compounds that can be further functionalized at the α position. [31]

Addition to carbonyls

In allylboration, an allylborane adds across an aldehyde or ketone with an allylic shift, and can then be converted to a homoallylic alcohol during workup. The reaction is much slower with ketones than aldehydes. [32] For example, in Nicolaou's epothilones synthesis, asymmetric allylboration (with an allylborane derived from chiral alpha-pinene) is the first step in a two-carbon homologation to acetogenin: [33]

AllylborationThenOzonolysis.png

Trifluoroborate salts are stabler than boronic acids and selectively alkylate aldehydes: [34]

AlkyltrifluoroboratesBatey2002.svg

Oxygenation

The hydroboration-oxidation reaction pair oxidizes the borane to an alcohol with hydrogen peroxide or to a carbonyl group with chromium oxide.

Oxidation of an alkenylborane gives an boron-free enol. [35]

Halogenation

Organoborane activation with hydroxide or alkoxide and treatment with X2 yields haloalkanes. With excess base, two of the three alkyl groups attached to the boron atom may convert to halide, but disiamylborane permits only halogenation of the hydroborated olefin: [36]

BoronScope5.png

Treatment of an alkenylborane with iodine or bromine induces migration of a boron-attached organic group. Alkynyl groups migrate selectively, forming enynes after treatment with sodium acetate and hydrogen peroxide: [37]

BoronScopeUnsat.png

Transmetalation and coupling

Organoboron compounds also transmetalate easily, especially to organopalladium compounds. In the Suzuki reaction, an aryl- or vinyl-boronic acid couples to an aryl- or vinyl-halide through a palladium(0) complex catalyst: [38]

Reducing agents

Borane hydrides such as 9-BBN and L-selectride (lithium tri(sec-butyl)borohydride) are reducing agents. An asymmetric catalyst for carbonyl reductions is the CBS catalyst, which relies on boron coordination to the carbonyl oxygen.

Other synthetic applications

Alcohols

Homologated primary alcohols result from the treatment of organoboranes with carbon monoxide and a hydride: [39]

BoronScopeCarb.png

Tertiary alcohols with two identical groups attached to the alcohol carbon may be synthesized through an alkynylborane double migration: [35]

BoronScope1.png

Carbonyl groups

Organoborates anions reductively eliminate against acyl halides. Here, the borate was generated from tri(cyclopentyl)borane and phenyllithium; the three cyclopentyl groups do not significantly migrate: [40]

BoronScope2.png

Applications

Organoboron chemistry is mainly of commercial value in the pharmaceutical industry.

Triethylborane was used to ignite the JP-7 fuel of the Pratt & Whitney J58 variable cycle engines powering the Lockheed SR-71 Blackbird.

Organoboron compounds have long been discussed for us as boron delivery agents in neutron capture therapy of cancer. [41]

Related Research Articles

Hydroboration–oxidation reaction is a two-step hydration reaction that converts an alkene into an alcohol. The process results in the syn addition of a hydrogen and a hydroxyl group where the double bond had been. Hydroboration–oxidation is an anti-Markovnikov reaction, with the hydroxyl group attaching to the less-substituted carbon. The reaction thus provides a more stereospecific and complementary regiochemical alternative to other hydration reactions such as acid-catalyzed addition and the oxymercuration–reduction process. The reaction was first reported by Herbert C. Brown in the late 1950s and it was recognized in his receiving the Nobel Prize in Chemistry in 1979.

The Suzuki reaction is an organic reaction, classified as a cross-coupling reaction, where the coupling partners are a boronic acid and an organohalide and the catalyst is a palladium(0) complex. It was first published in 1979 by Akira Suzuki, and he shared the 2010 Nobel Prize in Chemistry with Richard F. Heck and Ei-ichi Negishi for their contribution to the discovery and development of palladium-catalyzed cross-couplings in organic synthesis. This reaction is also known as the Suzuki–Miyaura reaction or simply as the Suzuki coupling. It is widely used to synthesize polyolefins, styrenes, and substituted biphenyls. Several reviews have been published describing advancements and the development of the Suzuki reaction. The general scheme for the Suzuki reaction is shown below, where a carbon-carbon single bond is formed by coupling a halide (R1-X) with an organoboron species (R2-BY2) using a palladium catalyst and a base. The organoboron species is usually synthesized by hydroboration or carboboration, allowing for rapid generation of molecular complexity.

<span class="mw-page-title-main">Bamford–Stevens reaction</span> Synthesis of alkenes by base-catalysed decomposition of tosylhydrazones

The Bamford–Stevens reaction is a chemical reaction whereby treatment of tosylhydrazones with strong base gives alkenes. It is named for the British chemist William Randall Bamford and the Scottish chemist Thomas Stevens Stevens (1900–2000). The usage of aprotic solvents gives predominantly Z-alkenes, while protic solvent gives a mixture of E- and Z-alkenes. As an alkene-generating transformation, the Bamford–Stevens reaction has broad utility in synthetic methodology and complex molecule synthesis.

In organic chemistry, hydroboration refers to the addition of a hydrogen-boron bond to certain double and triple bonds involving carbon. This chemical reaction is useful in the organic synthesis of organic compounds.

<span class="mw-page-title-main">Nucleophilic conjugate addition</span> Organic reaction

Nucleophilic conjugate addition is a type of organic reaction. Ordinary nucleophilic additions or 1,2-nucleophilic additions deal mostly with additions to carbonyl compounds. Simple alkene compounds do not show 1,2 reactivity due to lack of polarity, unless the alkene is activated with special substituents. With α,β-unsaturated carbonyl compounds such as cyclohexenone it can be deduced from resonance structures that the β position is an electrophilic site which can react with a nucleophile. The negative charge in these structures is stored as an alkoxide anion. Such a nucleophilic addition is called a nucleophilic conjugate addition or 1,4-nucleophilic addition. The most important active alkenes are the aforementioned conjugated carbonyls and acrylonitriles.

<span class="mw-page-title-main">Petasis reaction</span>

The Petasis reaction is the multi-component reaction of an amine, a carbonyl, and a vinyl- or aryl-boronic acid to form substituted amines.

<span class="mw-page-title-main">Boronic acid</span> Organic compound of the form R–B(OH)2

A boronic acid is an organic compound related to boric acid in which one of the three hydroxyl groups is replaced by an alkyl or aryl group. As a compound containing a carbon–boron bond, members of this class thus belong to the larger class of organoboranes.

<span class="mw-page-title-main">Phenylboronic acid</span> Chemical compound

Phenylboronic acid or benzeneboronic acid, abbreviated as PhB(OH)2 where Ph is the phenyl group C6H5-, is a boronic acid containing a phenyl substituent and two hydroxyl groups attached to boron. Phenylboronic acid is a white powder and is commonly used in organic synthesis. Boronic acids are mild Lewis acids which are generally stable and easy to handle, making them important to organic synthesis.

In organometallic chemistry, a migratory insertion is a type of reaction wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions, and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:

<span class="mw-page-title-main">Diisopinocampheylborane</span> Chemical compound

Diisopinocampheylborane is an organoborane that is useful for asymmetric synthesis. This colourless solid is the precursor to a range of related reagents. The compound was reported in 1961 by Zweifel and Brown in a pioneering demonstration of asymmetric synthesis using boranes. The reagent is mainly used for the synthesis of chiral secondary alcohols. The reagent is often depicted as a monomer but like most hydroboranes, it is dimeric with B-H-B bridges.

<span class="mw-page-title-main">Alpine borane</span> Chemical compound

Alpine borane is the commercial name for an organoboron compound that is used in organic synthesis. It is a colorless liquid, although it is usually encountered as a solution. A range of alkyl-substituted borane are specialty reagents in organic synthesis. Two such reagents that are closely related to Alpine borane are 9-BBN and diisopinocampheylborane.

<span class="mw-page-title-main">Liebeskind–Srogl coupling</span>

The Liebeskind–Srogl coupling reaction is an organic reaction forming a new carbon–carbon bond from a thioester and a boronic acid using a metal catalyst. It is a cross-coupling reaction. This reaction was invented by and named after Jiri Srogl from the Academy of Sciences, Czech Republic, and Lanny S. Liebeskind from Emory University, Atlanta, Georgia, USA. There are three generations of this reaction, with the first generation shown below. The original transformation used catalytic Pd(0), TFP = tris(2-furyl)phosphine as an additional ligand and stoichiometric CuTC = copper(I) thiophene-2-carboxylate as a co-metal catalyst. The overall reaction scheme is shown below.

<span class="mw-page-title-main">Borane dimethylsulfide</span> Chemical compound

Borane dimethylsulfide (BMS) is a chemical compound with the chemical formula BH3·S(CH3)2. It is an adduct between borane molecule and dimethyl sulfide molecule. It is a complexed borane reagent that is used for hydroborations and reductions. The advantages of BMS over other borane reagents, such as borane-tetrahydrofuran, are its increased stability and higher solubility. BMS is commercially available at much higher concentrations than its tetrahydrofuran counterpart and does not require sodium borohydride as a stabilizer, which could result in undesired side reactions. In contrast, BH3·THF requires sodium borohydride to inhibit reduction of THF to tributyl borate. BMS is soluble in most aprotic solvents.

Electrophilic amination is a chemical process involving the formation of a carbon–nitrogen bond through the reaction of a nucleophilic carbanion with an electrophilic source of nitrogen.

Reactions of alkenyl- and alkynylaluminium compounds involve the transfer of a nucleophilic alkenyl or alkynyl group attached to aluminium to an electrophilic atom. Stereospecific hydroalumination, carboalumination, and terminal alkyne metalation are useful methods for generation of the necessary alkenyl- and alkynylalanes.

An insertion reaction is a chemical reaction where one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:

Metal-catalyzed C–H borylation reactions are transition metal catalyzed organic reactions that produce an organoboron compound through functionalization of aliphatic and aromatic C–H bonds and are therefore useful reactions for carbon–hydrogen bond activation. Metal-catalyzed C–H borylation reactions utilize transition metals to directly convert a C–H bond into a C–B bond. This route can be advantageous compared to traditional borylation reactions by making use of cheap and abundant hydrocarbon starting material, limiting prefunctionalized organic compounds, reducing toxic byproducts, and streamlining the synthesis of biologically important molecules. Boronic acids, and boronic esters are common boryl groups incorporated into organic molecules through borylation reactions. Boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent and two hydroxyl groups. Similarly, boronic esters possess one alkyl substituent and two ester groups. Boronic acids and esters are classified depending on the type of carbon group (R) directly bonded to boron, for example alkyl-, alkenyl-, alkynyl-, and aryl-boronic esters. The most common type of starting materials that incorporate boronic esters into organic compounds for transition metal catalyzed borylation reactions have the general formula (RO)2B-B(OR)2. For example, bis(pinacolato)diboron (B2Pin2), and bis(catecholato)diborane (B2Cat2) are common boron sources of this general formula.

<span class="mw-page-title-main">Protodeboronation</span>

Protodeboronation, or protodeborylation is a chemical reaction involving the protonolysis of a boronic acid in which a carbon-boron bond is broken and replaced with a carbon-hydrogen bond. Protodeboronation is a well-known undesired side reaction, and frequently associated with metal-catalysed coupling reactions that utilise boronic acids. For a given boronic acid, the propensity to undergo protodeboronation is highly variable and dependent on various factors, such as the reaction conditions employed and the organic substituent of the boronic acid.

Norio Miyaura was a Japanese organic chemist. He was a professor of graduate chemical engineering at Hokkaido University. His major accomplishments surrounded his work in cross-coupling reactions / conjugate addition reactions of organoboronic acids and addition / coupling reactions of diborons and boranes. He is also the co-author of Cross-Coupling Reactions: A Practical Guide with M. Nomura E. S.. Miyaura was a world-known and accomplished researcher by the time he retired and so, in 2007, he won the Japan Chemical Society Award.

In organic chemistry, carboboration describes an addition of both a carbon and a boron moiety to certain carbon-containing double and triple bonds, such as alkenes, alkynes, and allenes.

References

Further reading

Footnotes

  1. ↑ Thomas 1991
  2. ↑ Elschenbroich, Christoph. Organometallics 3rd Ed. 2006 ISBN   3-527-29390-6 – Wiley-VCH, Weinheim
  3. 1 2 Negishi E.-I.; Idacavage, M. J. Org. React. 1985, 33, 1. doi:10.1002/0471264180.or033.01
  4. ↑ Bartlett, Ruth A.; Dias, H. V. Rasika; Olmstead, Marilyn M.; Power, Philip P.; Weese, Kenneth J. (1990). "Synthesis of the monomeric HBtrip2 (Trip - 2,4,6-iso-Pr3C6H2) and the x-ray crystal structures of [HBMes2]2 (Mes = 2,4,6,-Me3C6H2) and HBtrip2". Organometallics. 9: 146–150. doi:10.1021/om00115a023.
  5. ↑ Brown, H. C. Organic Syntheses via Boranes John Wiley & Sons, Inc. New York: 1975. ISBN   0-471-11280-1.
  6. ↑ Grimes, R. N. (2016). Carboranes (3rd ed.). New York: Academic Press. ISBN   9780128019054.
  7. ↑ Hall, Dennis G. Boronic Acids: Preparation, Applications in Organic Synthesis and Medicine. ISBN   3-527-30991-8
  8. ↑ Segawa Yasutomo; Yamashita Makoto; Nozaki Kyoko (2006). "Boryllithium: Isolation, Characterization, and Reactivity as a Boryl Anion". Science . 314 (5796): 113–115. Bibcode:2006Sci...314..113S. doi:10.1126/science.1131914. PMID   17023656. S2CID   21040230.
  9. ↑ Halford, Bethany. "Attacks: Electropositive element pressed into action as nucleophilic boryllithium" Chemical & Engineering News 2006; Volume 84 (41): 11
  10. ↑ Paetzold, Peter; Englert, Ulli; Finger, Rudolf; Schmitz, Thomas; Tapper, Alexander; Ziembinski, Ralf (2004). "Reactions at the Boron-Carbon Double Bond of Methyl(methylidene)boranes". Z. Anorg. Allg. Chem. 630 (4): 508–518. doi: 10.1002/zaac.200300396 .
  11. ↑ Curran, D. P.; Solovyev, A.; Makhlouf, Brahmi M.; Fensterbank, L.; Malacria, M.; Lacôte, E. (2011). "Synthesis and Reactions of N-Heterocyclic Carbene Boranes". Angewandte Chemie International Edition. 50 (44): 10294–10317. doi:10.1002/anie.201102717. PMID   21898724.
  12. ↑ Wang Yuzhong; Quillian, Brandon; Wei Pingrong; Chaitanya, S. Wannere; Xie Yaoming; King, R. Bruce; Schaefer III, Henry F.; v. R. Schleyer, Paul; Robinson, Gregory H. (2007). "A Stable Neutral Diborene Containing a B=B Double Bond". J. Am. Chem. Soc. 129 (41): 12412–12413. doi:10.1021/ja075932i. PMID   17887683.
  13. ↑ Dagani, Ron. "Neutral Diborene Is A First" Chemical & Engineering News October 1, 2007 Volume 85, Number 40 p. 10
  14. ↑ Braunschweig, Holger; Dewhurst, Rian D. (2013-03-25). "Single, Double, Triple Bonds and Chains: The Formation of Electron-Precise B-B Bonds". Angewandte Chemie International Edition. 52 (13): 3574–3583. doi:10.1002/anie.201208189. ISSN   1521-3773. PMID   23362015.
  15. ↑ Arrowsmith, Merle; Braunschweig, Holger; Stennett, Tom E. (2017-01-02). "Formation and Reactivity of Electron-Precise B−B Single and Multiple Bonds" (PDF). Angewandte Chemie International Edition. 56 (1): 96–115. doi:10.1002/anie.201610072. ISSN   1521-3773. PMID   27860056. Archived (PDF) from the original on July 22, 2018.
  16. ↑ Vedejs, E.; Chapman, R. W.; Fields, S. C.; Lin, S.; Schrimpf, M. R. (1995). "Conversion of Arylboronic Acids into Potassium Aryltrifluoroborates: Convenient Precursors of Arylboron Difluoride Lewis Acids". J. Org. Chem. 60 (10): 3020–3027. doi:10.1021/jo00115a016.
  17. ↑ Molander, Gary A.; Canturk, Belgin (2009). "Organotrifluoroborates and Monocoordinated Palladium Complexes as Catalysts—A Perfect Combination for Suzuki–Miyaura Coupling". Angew. Chem. Int. Ed. 48 (49): 9240–9261. doi:10.1002/anie.200904306. PMC   2917751 . PMID   19899086.
  18. ↑ Carey, F. A.; Sundberg, R. J. Advanced Organic Chemistry. ISBN   0-306-41088-5
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  33. ↑ Nicolaou, K. C.; Sarabia, F.; Ninkovic, S.; Finlay, M. R. V.; Boddy, C. N. C. (1998). "Probing the Ring Size of Epothilones: Total Synthesis of 14-, 15-, 17-, and 18 Epothilones A". Angewandte Chemie International Edition in English. 37 (1–2): 81–84. doi:10.1002/(sici)1521-3773(19980202)37:1/2<81::aid-anie81>3.0.co;2-c.
  34. ↑ Batey, Robert A.; Quach Tan D.; Shen Ming; Thadani, Avinash N.; Smil, David V.; Li Sze-Wan; MacKay, D. Bruce (2002). "Organoboron compounds as mild nucleophiles in Lewis acid- and transition metal-catalyzed C–C bond-forming reactions" (PDF). Pure Appl. Chem. 74 (1): 43–55. doi:10.1351/pac200274010043. S2CID   49223984.
  35. 1 2 Midland, M. M.; Brown, H. C. J. Org. Chem.1975, 40, 2845.
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  38. ↑ Miyaura Norio; Suzuki Akira (1995). "Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds". Chemical Reviews. 95 (7): 2457–2483. CiteSeerX   10.1.1.735.7660 . doi:10.1021/cr00039a007. S2CID   53050782.
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  41. ↑ Barth, Rolf F.; Mi, Peng; Yang, Weilian (December 2018). "Boron delivery agents for neutron capture therapy of cancer". Cancer Communications. 38 (1): 35. doi: 10.1186/s40880-018-0299-7 . ISSN   2523-3548. PMC   6006782 . PMID   29914561.
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