Organozinc compound

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Organozinc chemistry OrganozincLogo.png
Organozinc chemistry

Organozinc compounds in organic chemistry contain carbon (C) to zinc (Zn) chemical bonds. Organozinc chemistry is the science of organozinc compounds describing their physical properties, synthesis and reactions. [1] [2] [3] [4]

Contents

Organozinc compounds were among the first organometallic compounds made. They are less reactive than many other analogous organometallic reagents, such as Grignard and organolithium reagents. In 1848 Edward Frankland prepared the first organozinc compound, diethylzinc, by heating ethyl iodide in the presence of zinc metal. [5] This reaction produced a volatile colorless liquid that spontaneous combusted upon contact with air. Due to their pyrophoric nature, organozinc compounds are generally prepared using air-free techniques. They are unstable toward protic solvents. For many purposes they are prepared in situ, not isolated, but many have been isolated as pure substances and thoroughly characterized. [6]

Organozincs can be categorized according to the number of carbon substituents that are bound to the metal. [2] [3]

  1. Diorganozinc (R2Zn): A class of organozinc compounds in which two alkyl ligands. These may be further divided into subclasses depending on the other ligands attached
  2. Heteroleptic (RZnX): Compounds which an electronegative or monoanionic ligand (X), such as a halide, is attached to the zinc center with another alkyl or aryl substituent (R).
  3. Ionic organozinc compounds: This class is divided into organozincates (RnZn−) and organozinc cations (RZnL+
    n    ).

Bonding

In its coordination complexes zinc(II) adopts several coordination geometries, commonly octahedral, tetrahedral, and various pentacoordinate geometries. These structural flexibility can be attributed to zinc's electronic configuration [Ar]3d104s2. The 3d orbital is filled, and therefore, ligand field effects are nonexistent. Coordination geometry is thus determined largely by electrostatic and steric interactions. [2] Organozinc compounds usually are two- or three-coordinate, reflecting the strongly donating property of the carbanionic ligands.

Typical diorganozinc complexes have the formula R2Zn. Dialkylzinc compounds are monomeric with a linear coordination at the zinc atom. [7] A polar covalent bond exists between carbon and zinc, being polarized toward carbon due to the differences in electronegativity values (carbon: 2.5 & zinc: 1.65). The dipole moment of symmetric diorganozinc reagents can be seen as zero in these linear complexes, which explains their solubility in nonpolar solvents like cyclohexane. Unlike other binary metal alkyls, the diorganozinc species show a low affinity for complexation with ethereal solvent. Bonding in R2Zn is described as employing sp-hybridized orbitals on Zn. [2]

These structures cause zinc to have two bonding d-orbitals and three low-lying non-bonding d-orbitals (see non-bonding orbital), which are available for binding. When zinc lacks electron donating ligands it is unable to obtain coordination saturation, which is a consequence of the large atomic radius and low electron deficiency of zinc. Therefore, it is rare for bridging alkyl or aryl groups to occur due to the weak electron deficiency of the zinc atom. Although, it does occur in some cases such as Ph2Zn (Shown below) and which halogens are the organozinc can form metal clusters (see cluster chemistry). When a halogen ligand is added to the zinc atom both the acceptor and donor character of zinc is enhanced allowing for aggregation. [2]

Saturated diorganozinc reagents with bridging aryl groups Bridging aryl organozinc.png
Saturated diorganozinc reagents with bridging aryl groups

Synthesis

Several methods exist for the generation of organozinc compounds. Commercially available diorganozinc compounds are dimethylzinc, diethylzinc and diphenylzinc. These reagents are expensive and difficult to handle. In one study [8] [9] the active organozinc compound is obtained from much cheaper organobromine precursors:

Addition of diphenylzinc to an aldehyde DiphenylzincCarbonylAddition.png
Addition of diphenylzinc to an aldehyde

 

 

 

 

(2.1)

From zinc metal

Frankland's original synthesis of diethylzinc involves the reaction of ethyl iodide with zinc metal. The zinc must be activated to facilitate this redox reaction. One of such activated form of zinc employed by Frankland is zinc-copper couple. [5]

2 EtI + 2 Zn0 → Et
2Zn + ZnI
2

 

 

 

 

(2.2)

Riecke zinc, produced by in situ reduction of ZnCl2 with potassium, is another activated form of zinc. This form has proven useful for reactions such as Negishi coupling and Fukuyama coupling. Formation of organozinc reagents is facilitated for alkyl or aryl halides bearing electron-withdrawing substituents, e.g., nitriles and esters. [10] [11]

 

 

 

 

(2.3)

Using oxidative addition to get Negishi coupling precursors Zinc coupling.png
Using oxidative addition to get Negishi coupling precursors

 

 

 

 

(2.4)

Functional group exchange

The two most common zinc functional group interconversion reactions are with halides and boron, which is catalyzed by copper iodide (CuI) or base. The boron intermediate is synthesized by an initial hydroboration reaction followed by treatment with diethyl zinc. This synthesis shows the utility of organozinc reagents by displaying high selectivity for the most reactive site in the molecule, as well as creating useful coupling partners. [12]

Organozinc function group exchange with metals or boron reagents Functional group exchange.png
Organozinc function group exchange with metals or boron reagents

 

 

 

 

(2.5)

This group transfer reaction can be used in allylation, or other coupling reactions (such as Negishi coupling). [13]

Hiroshi Naka and coworkers utilized this group transfer reaction to get to the key intermediate Group Transfer Base Diagram.png
Hiroshi Naka and coworkers utilized this group transfer reaction to get to the key intermediate

 

 

 

 

(2.6)

β-Silyl diorganozinc compounds

One of the major drawbacks of diorganozinc alkylations is that only one of the two alkyl substituents is transferred. This problem can be solved by using Me3SiCH2- (TMSM), which is a non-transferable group. [14]

 

 

 

 

(2.7)

Transmetallation

Transmetallation is similar to the interconversions displayed above zinc can exchange with other metals such as mercury, lithium, copper, etc. One example of this reaction is the reaction of diphenylmercury with zinc metal to form diphenylzinc and metallic mercury:

HgPh2 + Zn → ZnPh2 + Hg

 

 

 

 

(2.8)

The benefit of transmetalling to zinc it is often more tolerant of other functional groups in the molecule due to the low reactivity which increases selectivity. [15]

Zakarian's synthesis of Maoecrystal V utilized an early stage zinc transmetallation to tolerate functionality Maoecrystal V transmetallation.png
Zakarian's synthesis of Maoecrystal V utilized an early stage zinc transmetallation to tolerate functionality

 

 

 

 

(2.9)

Organozinc can be obtained directly from zinc metal: [17] [18]

Organozinc Synthesis by Direct Insertion OrganozincSynthesisbyDirectInsertion.png
Organozinc Synthesis by Direct Insertion

 

 

 

 

(2.10)

In this method zinc is activated by 1,2-dibromoethane and trimethylsilyl chloride. A key ingredient is lithium chloride which quickly forms a soluble adduct with the organozinc compound thus removing it from the metal surface.

Reactions

In many of their reactions organozincs appear as intermediates.

Reformatsky reaction

This organic reaction can be employed to convert α-haloester and ketone or aldehyde to a β-hydroxyester. Acid is needed to protonate the resulting alkoxide during work up. The initial step is an oxidative addition of zinc metal into the carbon-halogen bond, thus forming a carbon-zinc enolate. This C-Zn enolate can then rearrange to the Oxygen-Zinc enolate via coordination. Once this is formed the other carbonyl containing starting material will coordinate in the manner shown below and give the product after protonation. [20] The benefits of the Reformatsky reaction over the conventional aldol reaction protocols is the following:

  1. Allows for exceedingly derivatized ketone substrates
  2. The ester enolate intermediate can be formed in the presence of enolizable moieties
  3. Well suited for intramolecular reactions

Below shows the six-membered transition state of the Zimmerman–Traxler model (Chelation Control, see Aldol reaction), in which R3 is smaller than R4. [21]

Basic mechanistic scheme of the Reformatsky reaction Reformatsky Rxn.png
Basic mechanistic scheme of the Reformatsky reaction

 

 

 

 

(3.1)

The Reformatsky reaction has been employed in numerous total syntheses such as the synthesis of C(16),C(18)-bis-epi-cytochalasin D: [22]

E. Vedejs total synthesis of C(16),C(18)-bis-epi-cytochalasin D uses a late stage Reformatsky reaction to access the natural product Reformatskytotsynth.png
E. Vedejs total synthesis of C(16),C(18)-bis-epi-cytochalasin D uses a late stage Reformatsky reaction to access the natural product

 

 

 

 

(3.2)

The Reformatsky reaction even allows for with zinc homo-enolates. [23] A modification of the Reformatsky reaction is the Blaise reaction. [21]

Scheme for the organozinc Blaise reaction, which utilizes an alpha-haloester and a functionalized cyano group Blaise Reaction.png
Scheme for the organozinc Blaise reaction, which utilizes an alpha-haloester and a functionalized cyano group

 

 

 

 

(3.3)

Simmons–Smith reaction

The Simmons–Smith reagent is used to prepare cyclopropanes from olefin using methylene iodide as the methylene source. The reaction is effected with zinc. The key zinc-intermediate formed is a carbenoid (iodomethyl)zinc iodide which reacts with alkenes to afford the cyclopropanated product. The rate of forming the active zinc species is increased via ultrasonication since the initial reaction occurs at the surface of the metal.

 

 

 

 

(3.4)

The butterfly TS for the Barbier reaction Butterfly ts.png
The butterfly TS for the Barbier reaction

 

 

 

 

(3.5)

Although the mechanism has not been fully elaborated it is hypothesized that the organozinc intermediate is a metal-carbenoid. The intermediate is believed to be a three-centered "butterfly-type". This intermediate can be directed by substituents, such as alcohols, to deliver the cyclopropane on the same side of the molecule. Zinc-copper couple is commonly used to activate zinc. [21]

Directing groups aid in the selectivity of the Simmons-Smith reaction Simmons-smith-example.png
Directing groups aid in the selectivity of the Simmons–Smith reaction

 

 

 

 

(3.6)

Titanium–zinc methylenation

Organozinc compounds derived from methylene bromide or iodide can electrophilically add to carbonyl groups to form terminal alkenes. [24] The reaction is mechanistically related to the Tebbe reaction and can be catalyzed by various Lewis acids (e.g. TiCl4 or Al2Me6). [25] The reaction is used to introduce deuterium into molecules for isotopic labeling or as an alternative to the Wittig reaction.

Negishi coupling

This powerful carbon-carbon bond forming cross-coupling reactions combines an organic halide and an organozinc halide reagent in the presence of a nickel or palladium catalyst. The organic halide reactant can be alkenyl, aryl, allyl, or propargyl. Alkylzinc coupling with alkyl halides such as bromides and chlorides have also been reported with active catalysts such as Pd-PEPPSI precatalysts, which strongly resist beta-hydride elimination (a common occurrence with alkyl substituents). [26] Either diorganic[ check spelling ] species or organozinc halides can be used as coupling partners during the transmetallation step in this reaction. Despite the low reactivity of organozinc reagents on organic electrophiles, these reagents are among the most powerful metal nucleophiles toward palladium. [27]

Alkylzinc species require the presence of at least a stoichiometric amount of halide ions in solution to form a "zincate" species of the form RZnX32−, before it can undergo transmetalation to the palladium centre. [28] This behavior contrasts greatly with the case of aryl zinc species. A key step in the catalytic cycle is a transmetalation in which a zinc halide exchanges its organic substituent for another halogen with the metal center.

An elegant example of Negishi coupling is Furstner's synthesis of amphidinolide T1: [29]

Negishi Cross coupling reaction in the total synthesis of Amphidinolide T1 Amphidinolide T1 Negishi.png
Negishi Cross coupling reaction in the total synthesis of Amphidinolide T1

 

 

 

 

(3.7)

Fukuyama coupling

Fukuyama coupling is a palladium-catalyzed reaction involving the coupling of an aryl, alkyl, allyl, or α,β- unsaturated thioester compound. This thioester compound can be coupled to a wide range of organozinc reagents in order to reveal the corresponding ketone product. This protocol is useful due to its sensitivity to functional groups such as ketone, acetate, aromatic halides, and even aldehydes. The chemoselectivity observed indicates ketone formation is more facile than oxidative addition of palladium into these other moieties. [30]

Basic scheme for Fukuyama coupling of thioesters Fukuyama Coupling.png
Basic scheme for Fukuyama coupling of thioesters

 

 

 

 

(3.8)

A further example of this coupling method is the synthesis of (+)-biotin. In this case, the Fukuyama coupling takes place with the thiolactone: [31]

Total synthesis of (+)-biotin using Fukuyama coupling (+)-Biotin Fukuyama Coupling.png
Total synthesis of (+)-biotin using Fukuyama coupling

 

 

 

 

(3.9)

Barbier reaction

The Barbier reaction involves nucleophilic addition of a carbanion equivalent to a carbonyl. The conversion is similar to the Grignard reaction. The organozinc reagent is generated via an oxidative addition into the alkyl halide. The reaction produces a primary, secondary, or tertiary alcohol via a 1,2-addition. The Barbier reaction is advantageous because it is a one-pot process: the organozinc reagent is generated in the presence of the carbonyl substrate. Organozinc reagents are also less water sensitive, thus this reaction can be conducted in water. Similar to the Grignard reaction, a Schlenk equilibrium applies, in which the more reactive dialkylzinc can be formed. [21]

Basic scheme of the Barbier reaction Barbier Reaction.png
Basic scheme of the Barbier reaction

 

 

 

 

(3.10)

The mechanism resembles the Grignard reaction, in which the metal alkoxide can be generated by a radical stepwise pathway, through single electron transfer, or concerted reaction pathway via a cyclic transition state. An example of this reaction is in Danishefsky's synthesis of cycloproparadicicol. By using the organozinc addition reaction conditions the other functionality of the dienone and the alkyne are tolerated: [32]

Samuel Danashefskey's total synthesis of cycloproparadiciciol utilizes an early stage Barbier reaction to access the key intermediate Barbier-Cycloproparadicicol.png
Samuel Danashefskey's total synthesis of cycloproparadiciciol utilizes an early stage Barbier reaction to access the key intermediate
.

 

 

 

 

(3.11)

Zinc acetylides

The formation of the zinc acetylide proceeds via the intermediacy of a dialkynyl zinc (functional group exchange). Catalytic processes have been developed such as Merck's ephedrine process. [33] Propargylic alcohols can be synthesized from zinc acetylides. These versatile intermediates can then be used for a wide range of chemical transformations such as cross-coupling reactions, hydrogenation, and pericyclic reactions. [34]

Synthesis of zinc propargylic alcohols ZnPropargylic alcohols.png
Synthesis of zinc propargylic alcohols

 

 

 

 

(3.12)

In the absence of ligands, the reaction is slow and inefficient. In the presence of chiral ligands, the reaction is fast and gives high conversion. Ryoji Noyori determined that a monozinc-ligand complex is the active species. [35]

Mono zinc is the most reactive species Mono zinc reactive.png
Mono zinc is the most reactive species

 

 

 

 

(3.13)

Diastereoselectivity for addition of organozinc reagents into aldehydes can be predicted by the following model by Noyori and David A. Evans: [36]

Favored conformer for organozinc aldehyde addition Favored conformer.png
Favored conformer for organozinc aldehyde addition

 

 

 

 

(3.14)

Zinc-acetylides are used in the HIV-1 reverse transcriptase inhibitor Efavirenz as well as in Merck's ephedrine derivatives . [37]

Merck's Effavirenz and ephedrine derivative synthesized via zinc acetylide Effavirenz & ephedrine.png
Merck's Effavirenz and ephedrine derivative synthesized via zinc acetylide

 

 

 

 

(3.15)

Organozincates

The first organozinc ate complex (organozincate) was reported in 1858 by James Alfred Wanklyn, [38] an assistant to Frankland and concerned the reaction of elemental sodium with diethylzinc:

2 Na + 3 ZnEt2 → 2 NaZnEt3 + Zn

 

 

 

 

(4.1)

Organozinc compounds that are strongly Lewis acidic are vulnerable to nucleophilic attack by alkali metals, such as sodium, and thus form these 'ate compounds'. Two types of organozincates are recognized: tetraorganozincates ([R4Zn]M2), which are dianionic, and triorganozincates ([R3Zn]M), which are monoanionic. Their structures, which are determined by the ligands, have been extensively characterized. [3]

Synthesis

Tetraorganozincates such as [Me4Zn]Li2 can be formed by mixing Me2Zn and MeLi in a 1:2 molar ratio of the rectants. Another example synthetic route to forming spriocyclic organozincates is shown below: [3]

Spirocyclic tetraorganozincate synthesis Tetraorganozincates.png
Spirocyclic tetraorganozincate synthesis

 

 

 

 

(4.2)

Triorganozincates compounds are formed by treating a diorganozinc such as (Me3SiCH2)2Zn with an alkali metal (K), or an alkali earth metal (Ba, Sr, or Ca). One example is [(Me3SiCH2)3Zn]K. Triethylzincate degrades to sodium hydridoethylzincate(II) as a result of beta-hydride elimination: [39]

2 NaZnEt3 → Na2Zn2H2Et4 + 2 C2H4

 

 

 

 

(4.3)

The product is an edge-shared bitetrahedral structure, with bridging hydride ligands.

Reactions

Although less commonly studied, organozincates often have increased reactivity and selectivity compared to the neutral diorganozinc compounds. They have been useful in stereoselective alkylations of ketones and related carbonyls, ring opening reactions. Aryltrimethylzincates participate in vanadium mediated C-C forming reactions. [3]

One useful organozincate reaction Organozincate rxn.png
One useful organozincate reaction

 

 

 

 

(4.4)

Organozinc(I) compounds

Low valent organozinc compounds having a Zn–Zn bond are also known. The first such compound, decamethyldizincocene, was reported in 2004. [40]

See also

Related Research Articles

Organometallic chemistry Study of organic compounds containing metal(s)

Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and selenium, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide, cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term "metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. Metal β-diketonates, alkoxides, dialkylamides, and metal phosphine complexes are representative members of this class. The field of organometallic chemistry combines aspects of traditional inorganic and organic chemistry.

Organolithium reagent

Organolithium reagents are organometallic compounds that contain carbon–lithium bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

The Stille reaction is a chemical reaction widely used in organic synthesis. The reaction involves the coupling of two organic groups, one of which is carried as an organotin compound. A variety of organic electrophiles provide the other coupling partner. The Stille reaction is one of many palladium-catalyzed coupling reactions.

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.

Simmons–Smith reaction

The Simmons–Smith reaction is an organic cheletropic reaction involving an organozinc carbenoid that reacts with an alkene to form a cyclopropane. It is named after Howard Ensign Simmons, Jr. and Ronald D. Smith. It uses a methylene free radical intermediate that is delivered to both carbons of the alkene simultaneously, therefore the configuration of the double bond is preserved in the product and the reaction is stereospecific.

Metalation is a chemical reaction that forms a bond to a metal. This reaction usually refers to the replacement of a halogen atom in an organic molecule with a metal atom, resulting in an organometallic compound. In the laboratory, metalation is commonly used to activate organic molecules during the formation of C—X bonds, which are necessary for the synthesis of many organic molecules.

Bamford–Stevens reaction

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The Corey–House synthesis is an organic reaction that involves the reaction of a lithium diorganylcuprate with an organic pseudohalide to form a new alkane, as well as an ill-defined organocopper species and lithium halide as byproducts.

Barbier reaction

The Barbier reaction is an organometallic reaction between an alkyl halide, a carbonyl group and a metal. The reaction can be performed using magnesium, aluminium, zinc, indium, tin, samarium, barium or their salts. The reaction product is a primary, secondary or tertiary alcohol. The reaction is similar to the Grignard reaction but the crucial difference is that the organometallic species in the Barbier reaction is generated in situ, whereas a Grignard reagent is prepared separately before addition of the carbonyl compound. Unlike many Grignard reagents, the organometallic species generated in a Barbier reaction are unstable and thus cannot be stored or sold commercially. Barbier reactions are nucleophilic addition reactions that involve relatively inexpensive, water insensitive metals or metal compounds. For this reason it is possible in many cases to run the reaction in water, making the procedure part of green chemistry. In contrast, Grignard reagents and organolithium reagents are highly moisture sensitive and must be used under an inert atmosphere without the presence of water. The Barbier reaction is named after Victor Grignard's teacher Philippe Barbier.

The Reformatsky reaction is an organic reaction which condenses aldehydes or ketones with α-halo esters using metallic zinc to form β-hydroxy-esters:

Grignard reagent Organometallic compounds used in organic synthesis

A Grignard reagent or Grignard compound is a chemical compound with the generic formula R−Mg−X, where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride Cl−Mg−CH3 and phenylmagnesium bromide (C6H5)−Mg−Br. They are a subclass of the organomagnesium compounds.

Diethylzinc Chemical compound

Diethylzinc (C2H5)2Zn, or DEZ, is a highly pyrophoric and reactive organozinc compound consisting of a zinc center bound to two ethyl groups. This colourless liquid is an important reagent in organic chemistry. It is available commercially as a solution in hexanes, heptane, or toluene, or as a pure liquid.

The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon-carbon bonds (C-C) in the process. A palladium (0) species is generally utilized as the metal catalyst, though nickel is sometimes used. A variety of nickel catalysts in either Ni0 or NiII oxidation state can be employed in Negishi cross couplings such as Ni(PPh3)4, Ni(acac)2, Ni(COD)2 etc.

Rieke metal

A Rieke metal is a highly reactive metal powder generated by reduction of a metal salt with an alkali metal. These materials are named after Reuben D. Rieke, who first described the recipes for their preparation. Among the many metals that have been generated by this method are Mg, Ca, Ti, Fe, Co, Ni, Cu, Zn, and In, which in turn are called Rieke-magnesium, Rieke-calcium, etc.

Organocopper compound Compound with carbon to copper bonds

Organocopper compounds is the chemistry of organometallic compounds containing a carbon to copper chemical bond. Organocopper chemistry is the study of organocopper compounds describing their physical properties, synthesis and reactions. They are reagents in organic chemistry.

In organic chemistry, the Kumada coupling is a type of cross coupling reaction, useful for generating carbon–carbon bonds by the reaction of a Grignard reagent and an organic halide. The procedure uses transition metal catalysts, typically nickel or palladium, to couple a combination of two alkyl, aryl or vinyl groups. The groups of Robert Corriu and Makoto Kumada reported the reaction independently in 1972.

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Paul Knochel is a French chemist and a member of the French Academy of Sciences.

In organometallic chemistry, metal–halogen exchange is a fundamental reaction that converts a organic halide into an organometallic product. The reaction commonly involves the use of electropositive metals and organochlorides, bromides, and iodides. Particularly well-developed is the use of metal–halogen exchange for the preparation of organolithium compounds.

References

  1. ↑ Knochel, Paul; Millot, Nicolas; Rodriguez, Alain L.; Tucker, Charles E. (2004). Organic Reactions. doi:10.1002/0471264180.or058.02. ISBN   0471264180.
  2. 1 2 3 4 5 The Chemistry of Organozinc Compounds (Patai Series: The Chemistry of Functional Groups), (Eds. Z. Rappoport and I. Marek), John Wiley & Sons: Chichester, UK, 2006, ISBN   0-470-09337-4.
  3. 1 2 3 4 5 Organozinc reagents – A Practical Approach, (Eds. P. Knochel and P. Jones), Oxford Medical Publications, Oxford, 1999, ISBN   0-19-850121-8.
  4. ↑ Synthetic Methods of Organometallic and Inorganic Chemistry Vol 5, Copper, Silver, Gold, Zinc, Cadmium, and Mercury, W.A. Herrmann Ed., ISBN   3-13-103061-5
  5. 1 2 E. Frankland, Liebigs Ann. Chem.,1849, 71, 171
  6. ↑ Elschenbroich, C. "Organometallics" (2006) Wiley-VCH: Weinheim. ISBN   978-3-527-29390-2
  7. ↑ John Bacsa; Felix Hanke; Sarah Hindley; Rajesh Odedra; George R. Darling; Anthony C. Jones; Alexander Steiner (2011). "The Solid State Structures of Dimethylzinc and Diethylzinc". Angewandte Chemie International Edition . 50 (49): 11685–11687. doi:10.1002/anie.201105099. PMC   3326375 . PMID   21919175.
  8. ↑ Kim, Jeung Gon; Walsh, Patrick J. (2006). "From Aryl Bromides to Enantioenriched Benzylic Alcohols in a Single Flask: Catalytic Asymmetric Arylation of Aldehydes". Angewandte Chemie International Edition. 45 (25): 4175–4178. doi: 10.1002/anie.200600741 . PMID   16721894.
  9. ↑ In this one-pot reaction bromobenzene is converted to phenyllithium by reaction with 4 equivalents of n-butyllithium, then transmetalation with zinc chloride forms diphenylzinc which continues to react in an asymmetric reaction first with the MIB ligand and then with 2-naphthylaldehyde to the alcohol. In this reaction formation of diphenylzinc is accompanied by that of lithium chloride, which unchecked, catalyses the reaction without MIB involvement to the racemic alcohol. The salt is effectively removed by chelation with tetraethylethylene diamine (TEEDA) resulting in an enantiomeric excess of 92%.
  10. ↑ Rieke, R. D. (1989). "Preparation of Organometallic Compounds from Highly Reactive Metal Powders". Science . 246 (4935): 1260–1264. Bibcode:1989Sci...246.1260R. doi:10.1126/science.246.4935.1260. PMID   17832221. S2CID   92794.
  11. ↑ Negishi, Ei-Ichi (2002). "A genealogy of Pd-catalyzed cross-coupling". Journal of Organometallic Chemistry. 653 (1–2): 34–40. doi:10.1016/S0022-328X(02)01273-1.
  12. ↑ Langer, Falk; Schwink, Lothar; Devasagayaraj, Arokiasamy; Chavant, Pierre-Yves; Knochel, Paul (1996). "Preparation of Functionalized Dialkylzincs via a Boron−Zinc Exchange. Reactivity and Catalytic Asymmetric Addition to Aldehydes". The Journal of Organic Chemistry. 61 (23): 8229–8243. doi:10.1021/jo961129n. ISSN   0022-3263. PMID   11667810.
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  14. ↑ Knochel,P.; et al. Angel. Chem. Int. Ed. Engl. 1997, volume 36, 1496-1498
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