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A Gilman reagent is a
If the Li+ ions is complexed with the 
National Pollutant Inventory - Copper and compounds fact sheet
lithium
Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...
and copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...
( diorganocopper) reagent compound, R2CuLi, where R is an alkyl
In organic chemistry, an alkyl group is an alkane missing one hydrogen.
The term ''alkyl'' is intentionally unspecific to include many possible substitutions.
An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloa ...
or aryl
In organic chemistry, an aryl is any functional group or substituent derived from an aromaticity, aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. "Aryl" is used for the sake of abbreviation or generalization, and "Ar ...
. These reagents are useful because, unlike related Grignard reagents and organolithium reagent
In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom ...
s, they react with organic halides to replace the halide group with an R group (the Corey–House reaction). Such displacement reactions allow for the synthesis of complex products from simple building blocks.
Reactions
These reagents were discovered byHenry Gilman
Henry Gilman (May 9, 1893 – November 7, 1986) was an American organic chemist known as the father of organometallic chemistry, the field within which his most notable work was done. He discovered the Gilman reagent, which bears his name.
Earl ...
and coworkers. Lithium dimethylcopper (CH3)2CuLi can be prepared by adding copper(I) iodide
Copper(I) iodide is the inorganic compound with the formula CuI. It is also known as cuprous iodide. It is useful in a variety of applications ranging from organic synthesis to cloud seeding.
Copper(I) iodide is white, but samples often appe ...
to methyllithium
Methyllithium is the simplest organolithium reagent with the empirical formula CH3Li. This s-block organometallic compound adopts an oligomeric structure both in solution and in the solid state. This highly reactive compound, invariably used in so ...
in tetrahydrofuran
Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...
at −78 °C. In the reaction depicted below, the Gilman reagent is a methylating reagent reacting with an alkyne in a conjugate addition
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 polari ...
, and the negative charge is trapped in a nucleophilic acyl substitution
Nucleophilic acyl substitution describe a class of substitution reactions involving nucleophiles and acyl compounds. In this type of reaction, a nucleophile – such as an alcohol, amine, or enolate – displaces the leaving group of an acyl deriv ...
with the ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...
group forming a cyclic enone.
Due to the softness of the nucleophile, they do 1,4 addition on conjugated enones, rather than 1,2 addition.
:
Structure
Lithium dimethylcuprate exists as adimer
Dimer may refer to:
* Dimer (chemistry), a chemical structure formed from two similar sub-units
** Protein dimer, a protein quaternary structure
** d-dimer
* Dimer model, an item in statistical mechanics, based on ''domino tiling''
* Julius Dimer ...
in diethyl ether
Diethyl ether, or simply ether, is an organic compound in the ether class with the formula , sometimes abbreviated as (see Pseudoelement symbols). It is a colourless, highly volatile, sweet-smelling ("ethereal odour"), extremely flammable li ...
forming an 8-membered ring. Similarly, lithium diphenylcuprate crystallizes as a dimeric etherate, .
crown ether
In organic chemistry, crown ethers are cyclic chemical compounds that consist of a ring containing several ether groups (). The most common crown ethers are cyclic oligomers of ethylene oxide, the repeating unit being ethyleneoxy, i.e., . Impo ...
12-crown-4, the resulting diorganylcuprate anions adopt a linear coordination geometry
The term coordination geometry is used in a number of related fields of chemistry and solid state chemistry/physics.
Molecules
The coordination geometry of an atom is the geometrical pattern formed by atoms around the central atom.
Inorganic coo ...
at copper.
Mixed cuprates
More useful generally than the Gilman reagents are the so-called mixed cuprates with the formula CuXsup>− and 2CuXsup>2−. Such compounds are often prepared by the addition of the organolithium reagent to copper(I) halides and cyanide. These mixed cuprates are more stable and more readily purified.Steven H. Bertz, Edward H. Fairchild, Karl Dieter, "Copper(I) Cyanide" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley & Sons. One problem addressed by mixed cuprates is the economical use of the alkyl group. Thus, in some applications, the mixed cuprate has the formula is prepared by combining thienyllithium and cuprous cyanide followed by the organic group to be transferred. In this higher order mixed cuprate, both the cyanide and thienyl groups do not transfer, only the R group does.Bruce H. Lipshutz Bruce H. Lipshutz (born 1951) is an American chemist. He is a professor at the University of California, Santa Barbara.
Biography
Lipshutz received his undergraduate degree in chemistry from Binghamton University in 1973. His graduate work was supe ...
, Robert Moretti, Robert Crow "Mixed Higher-order Cyanocuprate-induced Epoxide Openings: 1-Benzyloxy-4-penten-2-ol" Org. Synth. 1990, volume 69, pp. 80.
See also
*Organolithium reagent
In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom ...
* Organocopper
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 a ...
* Grignard reagent
* Cuprate (chemistry)
Cuprate loosely refers to a material that can be viewed as containing anionic copper complexes. Examples include tetrachloridocuprate ( uCl4sup>2−), the superconductor YBa2Cu3O7, and the organocuprates (e.g., dimethylcuprate u(CH3)2sup>∠...
External links
National Pollutant Inventory - Copper and compounds fact sheet
References
{{Lithium compounds Organolithium compounds Organocopper compounds Reagents for organic chemistry