Decarboxylative Claisen Rearrangement Research Articles

Decarboxylative Claisen rearrangement reactions: synthesis and reactivity of alkylidene-substituted indolines

Microwave-assisted decarboxylative Claisen rearrangement (dCr) reactions of substituted acetate derivatives of 3-(hydroxyalkyl)indoles give de-aromatised products. The reactivity of the resultant compounds was evaluated.

Transannular, decarboxylative Claisen rearrangement reactions for the synthesis of sulfur-substituted vinylcyclopropanes

Unsaturated epsilon-lactones bearing an alpha-arylsulfonyl or alpha-arylsulfoximinyl substituent undergo stereoselective transannular, decarboxylative Claisen rearrangement to give substituted vinylcyclopropanes.

Palladium-Catalyzed Decarboxylative Rearrangements of Allyl 2,2,2-Trifluoroethyl Malonates: Direct Access to Homoallylic Esters

Homoallylic esters are obtained in a single transformation from allyl 2,2,2-trifluoroethyl malonates by using a Pd(0) catalyst. Facile decarboxylation of allyl 2,2,2-trifluoroethyl malonates is attributed to a decrease in pK(a) compared to allyl methyl malonates. Subsequent reduction of the homoallylic 2,2,2-trifluoroethyl ester provides a (hydroxyethyl)cyclopentenyl derivative that represents a key intermediate in the synthesis of carbocyclic nucleosides. A select allyl 2,2,2-trifluoroethyl malonate undergoes a decarboxylative Claisen rearrangement to provide a regioisomeric homoallylic ester.

Reactivity of dearomatised furans synthesised via the decarboxylative Claisen rearrangement

The decarboxylative Claisen rearrangement (dCr) reaction of 1-(furan-2-yl)ethyl 2-tosylacetate afforded 2-ethylidene-3-(tosylmethyl)-2,3-dihydrofuran. Reaction of the dearomatised heterocycle with a variety of electrophiles gave addition products with excellent syn-diastereoselectivity. The furanol adducts were then utilised as functionalised scaffolds for a series of subsequent transformations.

A quantitative structure–reactivity relationship in decarboxylative Claisen rearrangement reactions of allylic tosylmalonate esters

First-order rate constants have been determined for the decarboxylative Claisen rearrangement reactions at 293 K of substituted methyl (E)-3-phenyl-2-propenyl 2-tosylmalonate esters, which show a linear free-energy relationship indicative of the development of positive charge on the benzylic position in the sigmatropic rearrangement transition-state.

Double decarboxylative Claisen rearrangement reactions: microwave-assisted de novo synthesis of pyridines

Microwave-assisted double decarboxylative Claisen rearrangement of bis(allyl) 2-tosylmalonates provides substituted 1,6-heptadienes, which may be alkylated, and then converted into pyridines by ozonolysis followed by reaction with ammonia generated in situ under microwave conditions.

Highly regioselective decarboxylative Claisen rearrangement reactions of diallyl 2-sulfonylmalonates

The decarboxylative Claisen rearrangement of a range of substituted diallyl 2-sulfonylmalonates is described. The substrates are made by C-carboxylation of the corresponding allyl sulfonylacetates with allyl para-nitrophenyl carbonates. The reactions display a high degree of regioselectivity, with allylic substituents possessing electron-rich substituents at the allyl three-position rearranging preferentially.

Total Synthesis of the Cytotoxic Guaipyridine Sesquiterpene Alkaloid (+)‐Cananodine.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Total Synthesis of the Cytotoxic Guaipyridine Sesquiterpene Alkaloid (+)‐Cananodine

AbstractThe enantiospecific total synthesis of the cytotoxic guaipyridine sesquiterpene alkaloid (+)‐cananodine (1) is described. A chiral pool/chiral auxiliary based approach is described for the synthesis of a key oxazolidinone intermediate. Subsequent key steps involve diastereoselective oxazolidinone allylation, cycloheptenylmethanol formation using ring‐closing olefin metathesis, microwave‐assisted decarboxylative Claisen rearrangement reaction, and use of a novel pyridine‐forming method.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

A [3,3]‐Sigmatropic Process Catalyzed by Acetate. The Decarboxylative Claisen Rearrangement.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Heteroaromatic Decarboxylative Claisen Rearrangement Reactions.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Asymmetric Decarboxylative Claisen Rearrangement Reactions of Sulfoximine‐Substituted Allylic Tosylacetic Esters.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A [3,3]-sigmatropic process catalysed by acetate. The decarboxylative Claisen rearrangement

Allylic tosylacetates and tosylmalonates undergo acetate-catalysed decarboxylative Claisen rearrangement in the presence of N, O-bis(trimethylsilyl)acetamide. The homoallylic sulfones formed in these transformations correspond to the products of regiospecific allylation of sulfone-stabilised carbanions. A mechanistic rationale is proposed.

Asymmetric Decarboxylative Claisen Rearrangement Reactions of Sulfoximine-Substituted Allylic Tosylacetic Esters

Allylic acetate esters containing a variety of N-arylsulfonyl sulfoximines on the acetyl residue have been prepared and submitted to the decarboxylative Claisen rearrangement reaction. Rearranged products were isolated in generally good yields, and diastereoselectivities up to 82:18 have been obtained. The N-(2,4,6-triisopropylphenylsulfonyl)-S-phenyl sulfoximine moiety gave the best selectivity. The stereochemistry of the major isomer was established by X-ray crystallography. A model to explain the stereochemical course of the rearrangement is proposed.

Decarboxylative Claisen Rearrangement Reactions of Allylic Tosylmalonate Esters.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Homoallylic Sulfones through a Decarboxylative Claisen Rearrangement Reaction

In hohen Ausbeuten entstehen die Homoallylsulfone 2 aus den Tosylessigsäure-Allylestern 1 sowie (sub)stöchiometrischen Mengen BSA und substöchiometrischen Mengen KOAc bei konventionellem Erhitzen oder unter Mikrowellenbestrahlung. Ein möglicher Mechanismus schließt die Bildung eines Silylketenacetals, [3,3]-sigmatrope Umlagerung und Desilylierung unter Decarboxylierung ein. BSA=N,O-Bis(trimethylsilyl)acetamid; Ts=p-Toluolsulfonyl.

Decarboxylative Claisen Rearrangement Reactions of Allylic Tosylmalonate Esters

[reaction: see text] Two different combinations of silylating agent and base are used for one-pot [3,3]-sigmatropic rearrangement-decarboxylation reactions of tosylmalonic mono(allylic) esters under mild conditions, providing the products of formal regiospecific allylation of methyl tosylacetate at the more substituted allylic terminus.

Synthesis of Homoallylic Sulfones through a Decarboxylative Claisen Rearrangement Reaction

A high-yielding preparation of homoallylic sulfones 2 entails the treatment of allylic tosylacetate esters 1 with stoichiometric or substoichiometric quantities of BSA and substoichiometric quantities of KOAc under conventional thermal or microwave conditions. A possible mechanism involves silyl ketene acetal formation, [3,3]-sigmatropic rearrangement, and desilylation-decarboxylation. BSA=N,O-bis(trimethylsilyl)acetamide; Ts=p-toluenesulfonyl.

Heteroaromatic Decarboxylative Claisen Rearrangement Reactions

Furan-2-ylmethyl, thien-2-ylmethyl and pyrrol-2-ylmethyl tosylacetates undergo facile decarboxylative Claisen rearrangement upon exposure to N,O-bis(trimethylsilyl)acetamide-potassium acetate to yield the corresponding 2,3-disubstituted heteroaromatic products in good yield. However, for 1-(thien-2-yl)ethyl tosylacetates and substrates derived from 3-(hydroxyalkyl)indoles rearomatisation does not occur.