Multi-component reaction

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A multi-component reaction (or MCR), sometimes referred to as a "Multi-component Assembly Process" (or MCAP), is a chemical reaction where three or more compounds react to form a single product. [1] By definition, multicomponent reactions are those reactions whereby more than two reactants combine in a sequential manner to give highly selective products that retain majority of the atoms of the starting material.

Contents

History and types of multicomponent reactions

Multicomponent reactions have been known for over 150 years. The first documented multicomponent reaction was the Strecker synthesis of α-amino cyanides in 1850 from which α-amino acids could be derived. A multitude of MCRs exist today, of which the isocyanide based MCRs are the most documented. Other MCRs include free-radical mediated MCRs, MCRs based on organoboron compounds and metal-catalyzed MCRs.

Isocyanide based MCRs are most frequently exploited because the isocyanide is an extraordinary functional group. It is believed to exhibit resonance between its tetravalent and divalent carbon forms. This induces the isocyanide group to undergo both electrophilic and nucleophilic reactions at the CII atom, which then converts to the CIV form in an exothermic reaction. The occurrence of isocyanides in natural products has also made it a useful functional group. The two most important isocyanide-based multicomponent reactions are the Passerini 3-component reaction to produce α-acyloxy carboxamides and the Ugi 4-component reaction, which yields the α-amino carboxamides. [2]

Examples of three component reactions:

The exact nature of this type of reaction is often difficult to assess, in collision theory a simultaneous interaction of 3 or more different molecules is less likely resulting in a low reaction rate. These reactions are more likely to involve a series of bimolecular reactions.

New MCR's are found by building a chemical library from combinatorial chemistry or by combining existing MCR's. [3] For example, a 7-component MCR results from combining the Ugi reaction with the Asinger reaction. [4] MCR's are an important tool in new drug discovery. MCR's can often be extended into combinatorial, solid phase or flow syntheses for developing new lead structures of active agents. [5]

See also

Related Research Articles

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Pyrrole is a heterocyclic, aromatic, organic compound, a five-membered ring with the formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3. Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as heme.

Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO2). Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carboxylation, the addition of CO2 to a compound. Enzymes that catalyze decarboxylations are called decarboxylases or, the more formal term, carboxy-lyases (EC number 4.1.1).

<span class="mw-page-title-main">Imidazole</span> Chemical compound

Imidazole (ImH) is an organic compound with the formula C3N2H4. It is a white or colourless solid that is soluble in water, producing a mildly alkaline solution. In chemistry, it is an aromatic heterocycle, classified as a diazole, and has non-adjacent nitrogen atoms in meta-substitution.

A lactam is a cyclic amide, formally derived from an amino alkanoic acid. The term is a portmanteau of the words lactone + amide.

The Passerini reaction is a chemical reaction involving an isocyanide, an aldehyde, and a carboxylic acid to form a α-acyloxy amide. This addition reaction is one of the oldest isocyanide-based multicomponent reactions (IMCR) and was first described in 1921 by Mario Passerini in Florence, Italy. It is typically carried out in aprotic solvents but can also be performed in ionic liquids such as water or Deep Eutectic solvents (DESs). It is a third order reaction; first order in each of the reactants. The Passerini reaction is often used in combinatorial and medicinal chemistry with recent utility in green chemistry and polymer chemistry. As isocyanides exhibit high functional group tolerance, chemoselectivity, regioselectivity, and stereoselectivity, the Passerini reaction has a wide range of synthetic applications.

An isocyanide is an organic compound with the functional group –N+≡C−. It is the isomer of the related nitrile (–C≡N), hence the prefix is isocyano. The organic fragment is connected to the isocyanide group through the nitrogen atom, not via the carbon. They are used as building blocks for the synthesis of other compounds.

The Ugi reaction is a multi-component reaction in organic chemistry involving a ketone or aldehyde, an amine, an isocyanide and a carboxylic acid to form a bis-amide. The reaction is named after Ivar Karl Ugi, who first reported this reaction in 1959.

The Strecker amino acid synthesis, also known simply as the Strecker synthesis, is a method for the synthesis of amino acids by the reaction of an aldehyde with ammonia in the presence of potassium cyanide. The condensation reaction yields an α-aminonitrile, which is subsequently hydrolyzed to give the desired amino acid. The method is used commercially for the production of racemic methionine from methional.

<span class="mw-page-title-main">Isatin</span> Chemical compound

Isatin, also known as tribulin, is an organic compound derived from indole with formula C8H5NO2. The compound was first obtained by Otto Linné Erdman and Auguste Laurent in 1840 as a product from the oxidation of indigo dye by nitric acid and chromic acids.

<span class="mw-page-title-main">Petasis reaction</span>

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<span class="mw-page-title-main">Liebeskind–Srogl coupling</span>

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The Bargellini reaction is a chemical reaction discovered in 1906 by Italian chemist Guido Bargellini. The original reaction was a mixture of the reagents phenol, chloroform, and acetone in the presence of a sodium hydroxide solution. Prior to Bargellini's research, the product attributed to this multi-component reaction (MCR) had been described as a phenol derivative in chemistry texts at the time. However, Bargellini demonstrated that a carboxylic acid derivative was actually the correct structure.

<span class="mw-page-title-main">A3 coupling reaction</span>

The A3 coupling (also known as A3 coupling reaction or the aldehyde-alkyne-amine reaction), coined by Prof. Chao-Jun Li of McGill University, is a type of multicomponent reaction involving an aldehyde, an alkyne and an amine which react to give a propargyl-amine.

<span class="mw-page-title-main">2-Carboxybenzaldehyde</span> Chemical compound

2-Carboxybenzaldehyde is a chemical compound. It consists of a benzene ring, with an aldehyde and a carboxylic acid as substituents that are ortho to each other. The compound exhibits ring–chain tautomerism: the two substituents can react with each other to form 3-hydroxyphthalide, a cyclic lactol. This lactol reacts readily with Grignard reagents, forming alkyl- and aryl-substituted phthalides. Other benzo-fused heterocyclic compounds can be derived from 2-carboxybenzaldehyde, including isoindolinones and phthalazinones, with a variety of pharmacological properties, such as the antihistamine azelastine.

The split and pool (split-mix) synthesis is a method in combinatorial chemistry that can be used to prepare combinatorial compound libraries. It is a stepwise, highly efficient process realized in repeated cycles. The procedure makes it possible to prepare millions or even trillions of compounds as mixtures that can be used in drug research.

References

  1. ↑ Multiple-Component Condensation Strategies for Combinatorial Library Synthesis Robert W. Armstrong, Andrew P. Combs, Paul A. Tempest, S. David Brown, and Thomas A. Keating Acc. Chem. Res., 1996, 29 (3), pp 123–131 doi : 10.1021/ar9502083
  2. ↑ Presentation on Multicomponent Reactions, Akul Mehta, 2009 (Presentation on Multicomponent Reactions).
  3. ↑ Recent progress in the chemistry of multicomponent reactions Ivar Ugi Pure Appl. Chem., 2001, Vol. 73, No. 1, pp. 187-191 doi : 10.1351/pac200173010187
  4. ↑ The discovery of new isocyanide-based multi-component reactions Alexander Dömling Current Opinion in Chemical Biology 2000, 4, 318-323. doi : 10.1016/S1367-5931(00)00095-8
  5. ↑ Multicomponent reactions Thomas J. J. Müller (Editor) Thematic Series in the Open Access Beilstein Journal of Organic Chemistry
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