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The Simmons-Smith reaction is an organic reaction
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 and organic redox reaction....
 in which a carbenoid
Carbenoid

In chemistry a carbenoid is a reactive intermediate that shares reaction characteristics with a carbene . In the Simmons-Smith reaction the carbenoid intermediate is a zinc / iodine complex that takes the form of...
 reacts with an alkene
Alkene

In organic chemistry, an alkene, olefin, or olefine is an Saturation chemical compound containing at least one carbon-to-carbon double bond....
 (or alkyne
Alkyne

Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms, with the formula CnH2n-2. The alkynes are traditionally known as acetylenes or the acetylene series, although the name acetylene is also used to refer specifically to the simplest member of the series, known as e...
) to form a cyclopropane
Cyclopropane

Cyclopropane is a cycloalkane molecule with the molecular formula C3H6, consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms....
. It is named after Howard Ensign Simmons, Jr.
Howard Ensign Simmons, Jr.

Howard Ensign Simmons, Jr. was an American chemist and discovered the Simmons-Smith reaction .Reference...
 and R. D. Smith.

Thus, cyclohexene
Cyclohexene

Cyclohexene is a colorless clear liquid cycloalkene with an intense aversive characteristic sharp smell reminiscent of an oil refinery.It is not very stable upon long term storage with exposure to light and air and should be distilled before use to eliminate organic peroxide....
, diiodomethane
Diiodomethane

Diiodomethane or methylene iodide is liquid halomethane insoluble in water, soluble in ether and alcohol. It has a relatively high refractive index of 1.741....
, and a zinc-copper couple
Zinc-copper couple

Zinc-copper couple is an alloy of zinc and copper that is employed as a reagent in organic synthesis. The ?couple? was popularized after the report by Simmons and Smith in 1959 of its application as an activated source of zinc required for formation of an Organozinc compound in the Simmons-Smith reaction of alkenes.....
 (as iodomethylzinc iodide
Iodomethylzinc iodide

Iodomethylzinc iodide is the active reagent in the Simmons-Smith reaction. For example, iodomethylzinc iodide, formed in situ from diiodomethane and a zinc-copper couple reacts with cyclohexene to give norcarane ....
, ICH2ZnI) yield norcarane
Norcarane

Norcarane, or bicyclo[4.1.0]heptane, is a colorless liquid. It is an organic compound prepared using the Simmons-Smith reaction, by the action of diiodomethane and a zinc-copper couple on cyclohexene in diethyl ether....
 (bicyclo[4.1.0]heptane).

Alternatively, diethylzinc
Diethylzinc

Diethylzinc 2Zn, or DEZ, is an organozinc compound composed of zinc bonded to two ethyl groups. This colourless liquid is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane, or toluene....
 is used instead of the zinc-copper couple.

The Simmons-Smith reaction is generally subject to steric effects
Steric effects

Steric effects arise from the fact that each atom within a molecule occupies a certain amount of space. If atoms are brought too close together, there is an associated cost in energy due to overlapping electron clouds , and this may affect the molecule's preferred shape and chemical reaction....
, and thus cyclopropanation usually takes place on the less hindered face.






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Encyclopedia


The Simmons-Smith reaction is an organic reaction
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 and organic redox reaction....
 in which a carbenoid
Carbenoid

In chemistry a carbenoid is a reactive intermediate that shares reaction characteristics with a carbene . In the Simmons-Smith reaction the carbenoid intermediate is a zinc / iodine complex that takes the form of...
 reacts with an alkene
Alkene

In organic chemistry, an alkene, olefin, or olefine is an Saturation chemical compound containing at least one carbon-to-carbon double bond....
 (or alkyne
Alkyne

Alkynes are hydrocarbons that have at least one triple bond between two carbon atoms, with the formula CnH2n-2. The alkynes are traditionally known as acetylenes or the acetylene series, although the name acetylene is also used to refer specifically to the simplest member of the series, known as e...
) to form a cyclopropane
Cyclopropane

Cyclopropane is a cycloalkane molecule with the molecular formula C3H6, consisting of three carbon atoms linked to each other to form a ring, with each carbon atom bearing two hydrogen atoms....
. It is named after Howard Ensign Simmons, Jr.
Howard Ensign Simmons, Jr.

Howard Ensign Simmons, Jr. was an American chemist and discovered the Simmons-Smith reaction .Reference...
 and R. D. Smith.

Thus, cyclohexene
Cyclohexene

Cyclohexene is a colorless clear liquid cycloalkene with an intense aversive characteristic sharp smell reminiscent of an oil refinery.It is not very stable upon long term storage with exposure to light and air and should be distilled before use to eliminate organic peroxide....
, diiodomethane
Diiodomethane

Diiodomethane or methylene iodide is liquid halomethane insoluble in water, soluble in ether and alcohol. It has a relatively high refractive index of 1.741....
, and a zinc-copper couple
Zinc-copper couple

Zinc-copper couple is an alloy of zinc and copper that is employed as a reagent in organic synthesis. The ?couple? was popularized after the report by Simmons and Smith in 1959 of its application as an activated source of zinc required for formation of an Organozinc compound in the Simmons-Smith reaction of alkenes.....
 (as iodomethylzinc iodide
Iodomethylzinc iodide

Iodomethylzinc iodide is the active reagent in the Simmons-Smith reaction. For example, iodomethylzinc iodide, formed in situ from diiodomethane and a zinc-copper couple reacts with cyclohexene to give norcarane ....
, ICH2ZnI) yield norcarane
Norcarane

Norcarane, or bicyclo[4.1.0]heptane, is a colorless liquid. It is an organic compound prepared using the Simmons-Smith reaction, by the action of diiodomethane and a zinc-copper couple on cyclohexene in diethyl ether....
 (bicyclo[4.1.0]heptane).

Alternatively, diethylzinc
Diethylzinc

Diethylzinc 2Zn, or DEZ, is an organozinc compound composed of zinc bonded to two ethyl groups. This colourless liquid is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane, or toluene....
 is used instead of the zinc-copper couple.

The Simmons-Smith reaction is generally subject to steric effects
Steric effects

Steric effects arise from the fact that each atom within a molecule occupies a certain amount of space. If atoms are brought too close together, there is an associated cost in energy due to overlapping electron clouds , and this may affect the molecule's preferred shape and chemical reaction....
, and thus cyclopropanation usually takes place on the less hindered face. However, when hydroxy substituents are present on chiral carbons, the zinc coordinates with the hydroxy substituents, directing cyclopropanation to the same face, which may or may not be sterically favorable:

The Simmons-Smith reagent, namely diiodomethane and diethylzinc, can react with allylic thioether
Thioether

A thioether is a functional group in organic chemistry that has the structure R1-S-R2 as shown on right. Like many other sulfur-containing compounds, Volatile organic compound thioethers characteristically have foul odors....
s to generate sulfur
Sulfur

Sulfur or sulphur is the chemical element that has the atomic number 16. It is denoted with the symbol S. It is an abundant Valence non-metal....
 ylides, which can subsequently undergo a 2,3-sigmatropic rearrangement
2,3-sigmatropic rearrangement

2,3-Sigmatropic rearrangements are a type of sigmatropic rearrangements and can be classified into two types. Rearrangements of allylic sulfoxides, amine oxides, selenoxides are pH....
, and will not cyclopropanate an alkene in the same molecule unless excess Simmons-Smith reagent is used:


Asymmetric Simmons-Smith reaction


Although asymmetric cyclopropanation methods based on diazo
Diazo

Diazo refers to a type of organic compound that has two linked nitrogen compounds. The general formula is R2C=N2. The simplest example of a diazo compound is diazomethane....
 compounds (see bisoxazoline ligand
Bisoxazoline ligand

In chemistry, bisoxazoline ligands are chiral ligands based on a bis oxazoline skeleton and used in combination with a metal compound in asymmetric synthesis as a chiral catalyst ....
) exist since 1966, the asymmetric Simmons-Smith reaction was introduced in 1992 with a reaction of cinnamyl alcohol
Cinnamyl alcohol

Cinnamyl alcohol is an organic compound that is found in esterified form in storax, balsam Peru and cinnamon leaves. It forms a white crystalline solid when pure, or a yellow oil when even slightly impure....
 with diethylzinc
Diethylzinc

Diethylzinc 2Zn, or DEZ, is an organozinc compound composed of zinc bonded to two ethyl groups. This colourless liquid is an important reagent in organic chemistry and available commercially as solutions of hexanes, heptane, or toluene....
, diiodomethane
Diiodomethane

Diiodomethane or methylene iodide is liquid halomethane insoluble in water, soluble in ether and alcohol. It has a relatively high refractive index of 1.741....
 and a chiral disulfonamide
Sulfonamide

Sulfonamide may refer to:* Sulfonamide - the sulfonamide functional group * Sulfonamide - the group of sulfonamide antibacterial drugs...
 in dichloromethane
Dichloromethane

Dichloromethane or methylene chloride is the chemical compound with the chemical formula CarbonHydrogen2Chlorine2....
:

The hydroxyl
Hydroxyl

Hydroxyl in chemistry stands for a molecule consisting of an oxygen atom and a hydrogen atom connected by a covalent bond. The neutral form is a hydroxyl Radical and the hydroxyl anion is called a hydroxide....
 group is a prerequisite serving as an anchor for zinc. In another version of this reaction the ligand is based on salen
Salen ligand

Salen is the abbreviation for a popular chelation ligand used in coordination chemistry and homogeneous catalysis. The name salen is a contraction for salicylic acid and ethylene diamine, which are the precursors to the ligand....
 and Lewis acid
Lewis acid

A Lewis acid is a chemical compound, A, that can accept a pair of electrons from a Lewis base, B, that acts as an electron-pair donor, forming an adduct, AB.Gilbert N....
 DIBAL is added:


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