Corey-House-Posner-Whitesides reaction
Encyclopedia
The Corey–Posner, Whitesides–House synthesis (also called the Corey–Posner, Whitesides–House reaction) is an organic reaction
that involves the reaction of a lithium
dialkyl cuprate
with an alkyl halide to form a new alkane
, an organocopper compound and a lithium halide
.
The second step requires the alkyl lithium compound to be treated with cuprous iodide
(CuI). This creates a lithium dialkyl cuprate compound. These compounds were first synthesized by Henry Gilman
of Iowa State University
, and are usually called Gilman reagent
s in honor of his contributions:
The lithium dialkyl cuprate is then treated with the second alkyl halide, which couples to the compound:
If second alkyl halide is not the same as the first, then cross-products are formed.
It is important to note that for this reaction to work successfully, the alkyl halide must be a methyl halide, benzyl halide, primary alkyl halide or a secondary cyclo alkyl halide. The relative simplicity of this reaction makes it a useful technique for synthesizing organic compounds.
, Gary H. Posner
of the Johns Hopkins University
, George M. Whitesides
of Harvard
, and Herbert O. House of the Georgia Institute of Technology
.
Organic reaction
Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, photochemical reactions and redox reactions. In organic synthesis,...
that involves the reaction of a lithium
Lithium
Lithium is a soft, silver-white metal that belongs to the alkali metal group of chemical elements. It is represented by the symbol Li, and it has the atomic number 3. Under standard conditions it is the lightest metal and the least dense solid element. Like all alkali metals, lithium is highly...
dialkyl cuprate
Cuprate
Cuprates are chemical compounds containing copper anion. Cuprates have been known for centuries and are widely used in inorganic and organic chemistry...
with an alkyl halide to form a new alkane
Alkane
Alkanes are chemical compounds that consist only of hydrogen and carbon atoms and are bonded exclusively by single bonds without any cycles...
, an organocopper compound and a lithium halide
Halide
A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. Many salts are halides...
.
- R2CuLi + R'-X → R-R' + RCu + LiX
Reaction mechanism
This reaction occurs in two steps. The alkyl halide is treated with lithium metal, and solvated in ether, which converts the alkyl halide into an alkyl lithium compound, R-Li. The starting R-X can be primary, secondary or tertiary alkyl halide:- R-X + 2Li → R-Li + Li-X
The second step requires the alkyl lithium compound to be treated with cuprous iodide
Copper(I) iodide
Copper 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....
(CuI). This creates a lithium dialkyl cuprate compound. These compounds were first synthesized by Henry Gilman
Henry Gilman
Henry Gilman 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....
of Iowa State University
Iowa State University
Iowa State University of Science and Technology, more commonly known as Iowa State University , is a public land-grant and space-grant research university located in Ames, Iowa, United States. Iowa State has produced astronauts, scientists, and Nobel and Pulitzer Prize winners, along with a host of...
, and are usually called Gilman reagent
Gilman reagent
A Gilman reagent is a lithium and copper reagent compound, R2CuLi, where R is an organic radical. These are useful because they react with organic chlorides, bromides, and iodides to replace the halide group with an R group. This is extremely useful in creating larger molecules from smaller...
s in honor of his contributions:
- 2RLi + CuI → R2CuLi + LiI
The lithium dialkyl cuprate is then treated with the second alkyl halide, which couples to the compound:
- R2CuLi + R'-X → R-R' + RCu + LiX
If second alkyl halide is not the same as the first, then cross-products are formed.
It is important to note that for this reaction to work successfully, the alkyl halide must be a methyl halide, benzyl halide, primary alkyl halide or a secondary cyclo alkyl halide. The relative simplicity of this reaction makes it a useful technique for synthesizing organic compounds.
Background
This reaction was developed by the co-operation of four organic chemists: E.J. Corey of Harvard UniversityHarvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
, Gary H. Posner
Gary H. Posner
Gary H. Posner is Scowe Professor of Chemistry at Johns Hopkins University in Baltimore, Maryland. Posner is known for his pioneering research in organocopper chemistry, including his involvement in the development of the Corey-House-Posner-Whitesides reaction.-Career:Posner was born in New York...
of the Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...
, George M. Whitesides
George Whitesides
George Whitesides may refer to:* George M. Whitesides, American chemist* George T. Whitesides, American space scientist and son of the above...
of Harvard
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
, and Herbert O. House of the Georgia Institute of Technology
Georgia Institute of Technology
The Georgia Institute of Technology is a public research university in Atlanta, Georgia, in the United States...
.