Heck-Matsuda reaction
Encyclopedia
The Heck-Matsuda reaction is an organic reaction
and a type of palladium
catalysed arylation of olefins
that uses arenediazonium salts as an alternative to aryl halides and triflate
s.
The use of arenediazonium salts presents some advantages over traditional aryl halide electrophile
s, for example, the use of phosphine
s as ligand
are not required and thus negating the requirement for anaerobic conditions, which makes the reaction more practical and easier to handle. Additionally, the reaction can be performed with or without a base and is often faster than traditional Heck protocols
.
Allylic alcohols, conjugated alkenes, unsaturated heterocycles and unactivated alkene
s are capable of being arylated with arenediazonium salts using simple catalysts such as palladium acetate (Pd(OAc)2) or tris(dibenzylideneacetone)dipalladium(0)
(Pd2dba3) at room temperature in air, and in benign and conventional solvents.
In addition to the intermolecular variant of the HM reaction, intramolecular cyclization processes have also been developed for the construction of a range of oxygen and nitrogen heterocycles.
The catalytic cycle
for the Heck-Matsuda arylation reaction has four main steps: oxidative addition
, migratory insertion
or carbopalladation, syn β-elimination and reductive elimination. The proposed Heck catalytic cycle involving cationic palladium with diazonium salts was reinforced by studies with mass spectrometry
(ESI) by Correia and co-workers. These results also show the complex interactions that occur in the coordination sphere of palladium during the Heck reaction with arenediazonium salt.
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,...
and a type of palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
catalysed arylation of olefins
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
that uses arenediazonium salts as an alternative to aryl halides and triflate
Triflate
Trifluoromethanesulfonate, also known by the trivial name triflate, is a functional group with the formula CF3SO3-. The triflate group is often represented by -OTf, as opposed to -Tf...
s.
The use of arenediazonium salts presents some advantages over traditional aryl halide electrophile
Electrophile
In general electrophiles are positively charged species that are attracted to an electron rich centre. In chemistry, an electrophile is a reagent attracted to electrons that participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile...
s, for example, the use of phosphine
Phosphine
Phosphine is the compound with the chemical formula PH3. It is a colorless, flammable, toxic gas. Pure phosphine is odourless, but technical grade samples have a highly unpleasant odor like garlic or rotting fish, due to the presence of substituted phosphine and diphosphine...
s as ligand
Ligand
In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
are not required and thus negating the requirement for anaerobic conditions, which makes the reaction more practical and easier to handle. Additionally, the reaction can be performed with or without a base and is often faster than traditional Heck protocols
Heck reaction
The Heck reaction is the chemical reaction of an unsaturated halide with an alkene and a base and palladium catalyst to form a substituted alkene. Together with the other palladium-catalyzed cross-coupling reactions, this reaction is of great importance, as it allows one to do substitution...
.
Allylic alcohols, conjugated alkenes, unsaturated heterocycles and unactivated alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
s are capable of being arylated with arenediazonium salts using simple catalysts such as palladium acetate (Pd(OAc)2) or tris(dibenzylideneacetone)dipalladium(0)
Tris(dibenzylideneacetone)dipalladium(0)
Trisdipalladium or Pd23 is an organometallic complex based on palladium and dibenzylideneacetone used in organic chemistry. It was discovered in 1970.-Preparation and structure:...
(Pd2dba3) at room temperature in air, and in benign and conventional solvents.
In addition to the intermolecular variant of the HM reaction, intramolecular cyclization processes have also been developed for the construction of a range of oxygen and nitrogen heterocycles.
The catalytic cycle
Catalytic cycle
A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst . The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc. Often such cycles show the conversion of a...
for the Heck-Matsuda arylation reaction has four main steps: oxidative addition
Oxidative addition
Oxidative addition and reductive elimination are two important and related classes of reactions in organometallic chemistry. Oxidative addition is a process that increases both the oxidation state and coordination number of a metal centre...
, migratory insertion
Migratory insertion
A migratory insertion is a type of reaction in organometallic chemistry 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...
or carbopalladation, syn β-elimination and reductive elimination. The proposed Heck catalytic cycle involving cationic palladium with diazonium salts was reinforced by studies with mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
(ESI) by Correia and co-workers. These results also show the complex interactions that occur in the coordination sphere of palladium during the Heck reaction with arenediazonium salt.