Claisen rearrangement

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Claisen rearrangement
Named after Rainer Ludwig Claisen
Reaction type Rearrangement reaction
Identifiers
Organic Chemistry Portal claisen-rearrangement
RSC ontology ID RXNO:0000148

The Claisen rearrangement is a powerful carbon–carbon bond-forming chemical reaction discovered by Rainer Ludwig Claisen. [1] The heating of an allyl vinyl ether will initiate a [3,3]-sigmatropic rearrangement to give a γ,δ-unsaturated carbonyl, driven by exergonically favored carbonyl CO bond formation Δ(ΔfH) = −327 kcal/mol (−1,370 kJ/mol). [2] [3] [4] [5]

The Claisen rearrangement Claisen rearrangement scheme.svg
The Claisen rearrangement

Mechanism

The Claisen rearrangement is an exothermic, concerted (bond cleavage and recombination) pericyclic reaction. Woodward–Hoffmann rules show a suprafacial, stereospecific reaction pathway. The kinetics are of the first order and the whole transformation proceeds through a highly ordered cyclic transition state and is intramolecular. Crossover experiments eliminate the possibility of the rearrangement occurring via an intermolecular reaction mechanism and are consistent with an intramolecular process. [6] [7]

There are substantial solvent effects observed in the Claisen rearrangement, where polar solvents tend to accelerate the reaction to a greater extent. Hydrogen-bonding solvents gave the highest rate constants. For example, ethanol/water solvent mixtures give rate constants 10-fold higher than sulfolane. [8] [9] Trivalent organoaluminium reagents, such as trimethylaluminium, have been shown to accelerate this reaction. [10] [11]

Variations

Aromatic Claisen rearrangement

The first reported Claisen rearrangement is the [3,3]-sigmatropic rearrangement of an allyl phenyl ether to intermediate 1, which quickly tautomerizes to a 2-allylphenol.

Aromatic Claisen 1.svg

The Claisen rearrangement can occur in domino fashion with a Cope rearrangement, in which case the allyl group appears to attack the para position on the ring: [12]

Aromatic Claisen with ortho-position substituted Aromatic Claisen with ortho-position Substituted.png
Aromatic Claisen with ortho-position substituted

Meta-substitution affects the regioselectivity of this rearrangement. [13] [14] For example, electron withdrawing groups (such as bromide) at the meta-position direct the rearrangement to the ortho-position (71% ortho product), while electron donating groups (such as methoxy), direct rearrangement to the para-position (69% para product). Additionally, presence of ortho substituents exclusively leads to para-substituted rearrangement products. [12] If an aldehyde or carboxylic acid occupies the ortho or para positions, the allyl side-chain displaces the group, releasing it as carbon monoxide or carbon dioxide, respectively. [15] [16]

Bellus–Claisen rearrangement

The Bellus–Claisen rearrangement is the reaction of allylic ethers, amines, and thioethers with ketenes to give γ,δ-unsaturated esters, amides, and thioesters. [17] [18] [19] This transformation was serendipitously observed by Bellus in 1979 through their synthesis of an intermediate to an insecticide, pyrethroid. Halogen substituted ketenes (R1, R2) are often used in this reaction for their high electrophilicity. Numerous reductive methods for the removal of the resulting α-haloesters, amides and thioesters have been developed. [20] [21] The Bellus-Claisen offers synthetic chemists a unique opportunity for ring expansion strategies.

The Bellus-Claisen rearrangement Claisen Bellus Rearrangement.png
The Bellus–Claisen rearrangement

Eschenmoser–Claisen rearrangement

The Eschenmoser–Claisen rearrangement proceeds by heating allylic alcohols in the presence of N,N-dimethylacetamide dimethyl acetal to form a γ,δ-unsaturated amide. This was developed by Albert Eschenmoser in 1964. [22] [23] Eschenmoser-Claisen rearrangement was used as a key step in the total synthesis of morphine. [24]

The Eschenmoser-Claisen rearrangement Eschenmoser-Claisen Rearrangement Scheme.png
The Eschenmoser-Claisen rearrangement

Mechanism: [12]

Eschenmoser-Claisen mechanism Eschenmoser Claisen Mechanism.png
Eschenmoser–Claisen mechanism

Ireland–Claisen rearrangement

The Ireland–Claisen rearrangement is the reaction of an allylic carboxylate with a strong base (such as lithium diisopropylamide) to give a γ,δ-unsaturated carboxylic acid. [25] [26] [27] The rearrangement proceeds via silylketene acetal, which is formed by trapping the lithium enolate with chlorotrimethylsilane. Like the Bellus-Claisen (above), Ireland-Claisen rearrangement can take place at room temperature and above. The E- and Z-configured silylketene acetals lead to anti and syn rearranged products, respectively. [28] There are numerous examples of enantioselective Ireland-Claisen rearrangements found in literature to include chiral boron reagents and the use of chiral auxiliaries. [29] [30]

The Ireland-Claisen rearrangement TOC for IC.jpg
The Ireland–Claisen rearrangement

Johnson–Claisen rearrangement

The Johnson–Claisen rearrangement is the reaction of an allylic alcohol with an orthoester to yield a γ,δ-unsaturated ester. [31] Weak acids, such as propionic acid, have been used to catalyze this reaction. This rearrangement often requires high temperatures (100–200 °C) and can take anywhere from 10 to 120 hours to complete. [32] However, microwave assisted heating in the presence of KSF-clay or propionic acid have demonstrated dramatic increases in reaction rate and yields. [33] [34]

The Johnson-Claisen rearrangement Johnson-Claisen Rearrangement Scheme.png
The Johnson–Claisen rearrangement

Mechanism: [12]

Johnson-Claisen mechanism Johnson Claisen Mechanism.png
Johnson–Claisen mechanism

Kazmaier–Claisen rearrangement

The Kazmaier-Claisen rearrangement is the reaction of an unsaturated amino acid ester with a strong base (such as lithium diisopropylamide) and a metal salt at –78 °C to give a chelated enolate as intermediate. [35] [36] While different metal salts can be used to form the enolate, the use of zinc chloride results in the highest yield and gives the best stereospecificity. [37] The enolate species rearranges at –20 °C to form an amino acid with an allylic side chain in α-position. This method was described by Uli Kazmaier in 1993. [38]

The Kazmaier-Claisen rearrangement Kazmaier-Claisen-rearrangement.svg
The Kazmaier-Claisen rearrangement

Photo-Claisen rearrangement

The Claisen rearrangement of aryl ethers can also be performed as a photochemical reaction. In addition to the traditional ortho product obtained under thermal conditions (the [3,3] rearrangement product), the photochemical variation also gives the para product ([3,5] product), alternate isomers of the allyl group (for example, [1,3] and [1,5] products), and simple loss of the ether group, and even can rearrange alkyl ethers in addition to allyl ethers. The photochemical reaction occurs via a stepwise process of radical-cleavage followed by bond-formation rather than as a concerted pericyclic reaction, which therefore allows the opportunity for the greater variety of possible substrates and product isomers. [39] The [1,3] and [1,5] results of the photo-Claisen rearrangement are analogous to the photo-Fries rearrangement of aryl esters and related acyl compounds. [40]

Hetero-Claisens

Aza–Claisen

An iminium can serve as one of the pi-bonded moieties in the rearrangement. [41]

An example of the Aza-Claisen rearrangement Aza-Claisen Rearrangement Example.png
An example of the Aza–Claisen rearrangement

Chen–Mapp reaction

The Chen–Mapp reaction, also known as the [3,3]-phosphorimidate rearrangement or Staudinger–Claisen reaction, installs a phosphite in the place of an alcohol and takes advantage of the Staudinger reduction to convert this to an allylic amine. The subsequent Claisen is driven by the fact that a P=O double bond is more energetically favorable than a P=N double bond. [42]

The Mapp reaction MappReaction.png
The Mapp reaction

Overman rearrangement

The Overman rearrangement (named after Larry Overman) is a Claisen rearrangement of allylic trichloroacetimidates to allylic trichloroacetamides. [43] [44] [45]

The Overman rearrangement Overman Rearrangement scheme.svg
The Overman rearrangement

The Overman rearrangement is applicable to the synthesis of vicinal diamino compounds from 1,2-vicinal allylic diols.

Zwitterionic Claisen rearrangement

Unlike typical Claisen rearrangements which require heating, zwitterionic Claisen rearrangements take place at or below room temperature. The acyl ammonium ions are highly selective for Z-enolates under mild conditions. [46] [47]

The zwitterionic Claisen rearrangement Zwitterionic Claisen Rearrangement Scheme.png
The zwitterionic Claisen rearrangement

In nature

The enzyme chorismate mutase (EC 5.4.99.5) catalyzes the Claisen rearrangement of chorismate to prephenate, an intermediate in the biosynthetic pathway towards the synthesis of phenylalanine and tyrosine. [48]

Chorismate mutase catalyzes a Claisen rearrangement Chorismate Mutase Scheme.png
Chorismate mutase catalyzes a Claisen rearrangement

History

Discovered in 1912, the Claisen rearrangement is the first recorded example of a [3,3]-sigmatropic rearrangement. [1] [49] [50]

See also

Related Research Articles

An ylide or ylid is a neutral dipolar molecule containing a formally negatively charged atom (usually a carbanion) directly attached to a heteroatom with a formal positive charge (usually nitrogen, phosphorus or sulfur), and in which both atoms have full octets of electrons. The result can be viewed as a structure in which two adjacent atoms are connected by both a covalent and an ionic bond; normally written X+–Y−. Ylides are thus 1,2-dipolar compounds, and a subclass of zwitterions. They appear in organic chemistry as reagents or reactive intermediates.

<span class="mw-page-title-main">Organolithium reagent</span> Chemical compounds containing C–Li bonds

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 to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

In organic chemistry, a sigmatropic reaction is a pericyclic reaction wherein the net result is one sigma bond (σ-bond) is changed to another σ-bond in an intramolecular reaction. In this type of rearrangement reaction, a substituent moves from one part of a π-system to another part with simultaneous rearrangement of the π-system. True sigmatropic reactions are usually uncatalyzed, although Lewis acid catalysis is possible. Sigmatropic reactions often have transition-metal catalysts that form intermediates in analogous reactions. The most well-known of the sigmatropic rearrangements are the [3,3] Cope rearrangement, Claisen rearrangement, Carroll rearrangement, and the Fischer indole synthesis.

<span class="mw-page-title-main">Michael addition reaction</span> Reaction in organic chemistry

In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor and a Michael acceptor to produce a Michael adduct by creating a carbon-carbon bond at the acceptor's β-carbon. It belongs to the larger class of conjugate additions and is widely used for the mild formation of carbon-carbon bonds.

<span class="mw-page-title-main">Enolate</span> Organic anion formed by deprotonating a carbonyl (>C=O) compound

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The Carroll rearrangement is a rearrangement reaction in organic chemistry and involves the transformation of a β-keto allyl ester into a α-allyl-β-ketocarboxylic acid. This organic reaction is accompanied by decarboxylation and the final product is a γ,δ-allylketone. The Carroll rearrangement is an adaptation of the Claisen rearrangement and effectively a decarboxylative allylation.

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<span class="mw-page-title-main">Chiral auxiliary</span> Stereogenic group placed on a molecule to encourage stereoselectivity in reactions

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<span class="mw-page-title-main">2,3-sigmatropic rearrangement</span> Class of chemical reaction

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<span class="mw-page-title-main">Baker–Venkataraman rearrangement</span>

The Baker–Venkataraman rearrangement is the chemical reaction of 2-acetoxyacetophenones with base to form 1,3-diketones.

<span class="mw-page-title-main">Ortho ester</span> Chemical group with the structure RC(OR)3

In organic chemistry, an ortho ester is a functional group containing three alkoxy groups attached to one carbon atom, i.e. with the general formula RC(OR')3. Orthoesters may be considered as products of exhaustive alkylation of unstable orthocarboxylic acids and it is from these that the name 'ortho ester' is derived. An example is ethyl orthoacetate, CH3C(OCH2CH3)3, more correctly known as 1,1,1-triethoxyethane.

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The Ireland–Claisen rearrangement is a chemical reaction of an allylic ester with strong base to give an γ,δ-unsaturated carboxylic acid.

Electrophilic amination is a chemical process involving the formation of a carbon–nitrogen bond through the reaction of a nucleophilic carbanion with an electrophilic source of nitrogen.

The [2,3]-Wittig rearrangement is the transformation of an allylic ether into a homoallylic alcohol via a concerted, pericyclic process. Because the reaction is concerted, it exhibits a high degree of stereocontrol, and can be employed early in a synthetic route to establish stereochemistry. The Wittig rearrangement requires strongly basic conditions, however, as a carbanion intermediate is essential. [1,2]-Wittig rearrangement is a competitive process.

William Clark Still is an American organic chemist. As a distinguished professor at Columbia University, Clark Still made significant contributions to the field of organic chemistry, particularly in the areas of natural product synthesis, reaction development, conformational analysis, macrocyclic stereocontrol, and computational chemistry. Still and coworkers also developed the purification technique known as flash column chromatography which is widely used for the purification of organic compounds.

Rearrangements, especially those that can participate in cascade reactions, such as the aza-Cope rearrangements, are of high practical as well as conceptual importance in organic chemistry, due to their ability to quickly build structural complexity out of simple starting materials. The aza-Cope rearrangements are examples of heteroatom versions of the Cope rearrangement, which is a [3,3]-sigmatropic rearrangement that shifts single and double bonds between two allylic components. In accordance with the Woodward-Hoffman rules, thermal aza-Cope rearrangements proceed suprafacially. Aza-Cope rearrangements are generally classified by the position of the nitrogen in the molecule :

In organic chemistry, the oxy-Cope rearrangement is a chemical reaction. It involves reorganization of the skeleton of certain unsaturated alcohols. It is a variation of the Cope rearrangement in which 1,5-dien-3-ols are converted to unsaturated carbonyl compounds by a mechanism typical for such a [3,3]-sigmatropic rearrangement.

References

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  2. ↑ Hiersemann, M.; Nubbemeyer, U. (2007) The Claisen Rearrangement. Wiley-VCH. ISBN   3-527-30825-3
  3. ↑ Rhoads, S. J.; Raulins, N. R. (1975). "The Claisen and Cope Rearrangements". Org. React. 22: 1–252. doi:10.1002/0471264180.or022.01. ISBN   978-0471264187.
  4. ↑ Ziegler, F. E. (1988). "The thermal, aliphatic Claisen rearrangement". Chem. Rev. 88 (8): 1423–1452. doi:10.1021/cr00090a001.
  5. ↑ Wipf, P. (1991). "Claisen Rearrangements". Compr. Org. Synth. 5: 827–873. doi:10.1016/B978-0-08-052349-1.00140-2. ISBN   978-0-08-052349-1.
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  7. ↑ Francis A. Carey; Richard J. Sundberg (2007). Advanced Organic Chemistry: Part A: Structure and Mechanisms. Springer. pp. 934–935. ISBN   978-0-387-44897-8.
  8. ↑ Claisen, L. (1912). "Über Umlagerung von Phenol-allyläthern in C-Allyl-phenole". Chemische Berichte . 45 (3): 3157–3166. doi:10.1002/cber.19120450348.
  9. ↑ Claisen, L.; Tietze, E. (1925). "Über den Mechanismus der Umlagerung der Phenol-allyläther". Chemische Berichte . 58 (2): 275. doi:10.1002/cber.19250580207.
  10. ↑ Goering, H. L.; Jacobson, R. R. (1958). "A Kinetic Study of the ortho-Claisen Rearrangement1". J. Am. Chem. Soc. 80 (13): 3277. doi:10.1021/ja01546a024.
  11. ↑ White, W. N.; Wolfarth, E. F. (1970). "The o-Claisen rearrangement. VIII. Solvent effects". J. Org. Chem. 35 (7): 2196. doi:10.1021/jo00832a019.
  12. 1 2 3 4 László Kürti; Barbara Czakó (2005). Strategic Applications of Named Reactions in Organic Synthesis: Background And Detailed Mechanics: 250 Named Reactions. Academic Press. ISBN   978-0-12-429785-2 . Retrieved 27 March 2013.
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  14. ↑ Gozzo, Fábio Cesar; Fernandes, Sergio Antonio; Rodrigues, Denise Cristina; Eberlin, Marcos Nogueira; Marsaioli, Anita Jocelyne (2003). "Regioselectivity in Aromatic Claisen Rearrangements". The Journal of Organic Chemistry. 68 (14): 5493–5499. doi:10.1021/jo026385g. PMID   12839439.
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  17. ↑ Malherbe, R.; Bellus, D. (1978). "A New Type of Claisen Rearrangement Involving 1,3-Dipolar Intermediates. Preliminary communication". Helv. Chim. Acta. 61 (8): 3096–3099. doi:10.1002/hlca.19780610836.
  18. ↑ Malherbe, R.; Rist, G.; Bellus, D. (1983). "Reactions of haloketenes with allyl ethers and thioethers: A new type of Claisen rearrangement". J. Org. Chem. 48 (6): 860–869. doi:10.1021/jo00154a023.
  19. ↑ Gonda, J. (2004). "The Belluš–Claisen Rearrangement". Angew. Chem. Int. Ed. 43 (27): 3516–3524. doi:10.1002/anie.200301718. PMID   15293240.
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  40. ↑ IUPAC , Compendium of Chemical Terminology , 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) " photo-Fries rearrangement ". doi : 10.1351/goldbook.P04614
  41. ↑ Kurth, M. J.; Decker, O. H. W. (1985). "Enantioselective preparation of 3-substituted 4-pentenoic acids via the Claisen rearrangement". J. Org. Chem. 50 (26): 5769–5775. doi:10.1021/jo00350a067.
  42. ↑ Chen, B.; Mapp, A. (2005). "Thermal and catalyzed [3,3]-phosphorimidate rearrangements". Journal of the American Chemical Society. 127 (18): 6712–6718. doi:10.1021/ja050759g. PMID   15869293.
  43. ↑ Overman, L. E. (1974). "Thermal and mercuric ion catalyzed [3,3]-sigmatropic rearrangement of allylic trichloroacetimidates. 1,3-Transposition of alcohol and amine functions". Journal of the American Chemical Society. 96 (2): 597–599. doi:10.1021/ja00809a054.
  44. ↑ Overman, L. E. (1976). "A general method for the synthesis of amines by the rearrangement of allylic trichloroacetimidates. 1,3-Transposition of alcohol and amine functions". Journal of the American Chemical Society. 98 (10): 2901–2910. doi:10.1021/ja00426a038.
  45. ↑ Clizbe, L. A.; Overman, L. E. (1978). "Allylically Transposed Amines from Allylic Alcohols: 3,7-Dimethyl-1,6-Octadien-3-Amine". Organic Syntheses. 58: 4. doi:10.15227/orgsyn.058.0004.
  46. ↑ Yu, C.-M.; Choi, H.-S.; Lee, J.; Jung, W.-H.; Kim, H.-J. (1996). "Self-regulated molecular rearrangement: Diastereoselective zwitterionic aza-Claisen protocol". J. Chem. Soc., Perkin Trans. 1 (2): 115–116. doi:10.1039/p19960000115.
  47. ↑ Nubbemeyer, U. (1995). "1,2-Asymmetric Induction in the Zwitterionic Claisen Rearrangement of Allylamines". J. Org. Chem. 60 (12): 3773–3780. doi:10.1021/jo00117a032.
  48. ↑ Ganem, B. (1996). "The Mechanism of the Claisen Rearrangement: Déjà Vu All over Again". Angew. Chem. Int. Ed. Engl. 35 (9): 936–945. doi:10.1002/anie.199609361.
  49. ↑ Claisen, L.; Tietze, E. (1925). "Über den Mechanismus der Umlagerung der Phenol-allyläther". Chemische Berichte . 58 (2): 275. doi:10.1002/cber.19250580207.
  50. ↑ Claisen, L.; Tietze, E. (1926). "Über den Mechanismus der Umlagerung der Phenol-allyläther. (2. Mitteilung)". Chemische Berichte . 59 (9): 2344. doi:10.1002/cber.19260590927.
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