Selective .gamma.-substitution of .alpha.,.beta.-unsaturated esters via .alpha.-trimethylsilyl .beta.,.gamma.-unsaturated esters

Albaugh-Robertson, Pamela; Katzenellenbogen, John A.

doi:10.1021/jo00174a026

Cited by 43 publications

(4 citation statements)

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“…Selective carbon-carbon bond formation at the y position is important for the synthesis of terpenoid natural products and consequently a variety of methods have been developed to control the reactive site (11)(12)(13)(14)(15). A number of different metals and counterions have been examined, including lithium, magnesium, zinc, tin, silicon, palladium, etc.…”

Section: Introductionmentioning

confidence: 99%

Cadmium chloride mediated regiocontrol of dienolates and ketene thioacetals: γ condensation with aldehydes

Lei¹,

Fallis²

1991

Can. J. Chem.

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Bo LEI and ALEX G. FALLIS. Can. J. Chem. 69, 1450 (1991.The use of cadmium chloride to control the regioselectivity of vinylogous anions upon condensation with aldehydes is described. Addition occurred preferentially at the y position with substituted crotonates and 2-ethylidene-l,3-dithiane (6).Experiments demonstrated that this selectivity arose as a consequence of isomerization of the initially formed kinetic a product to the thermodynamic y product (e.g., 2 to 4). The optimum results were achieved with 2 equivalents of cadmium chloride and quenching at 0°C.

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Section: Introductionmentioning

confidence: 99%

Cadmium chloride mediated regiocontrol of dienolates and ketene thioacetals: γ condensation with aldehydes

Lei¹,

Fallis²

1991

Can. J. Chem.

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“…Prepared from 1 (30 mg, 0.11 mmol), trans- styrenylboronic acid (161 mg, 1.1 mmol), and Cs 2 CO 3 (289 mg, 0.9 mmol) using a procedure similar to that described for compound 3 that provided the known compound as a colorless oil (21 mg, 88%): 1 H NMR (400 MHz, acetone- d 6 ) δ 7.61−7.59 (m, 2H), 7.40−7.36 (m, 2H), 7.33−7.29 (m, 1H), 7.13−7.02 (m, 2H) 5.98 (s, 1H), 4.14 (q, J = 7.2 Hz, 2H), 2.40 (d, J = 1.3 Hz, 3H), 1.26 (t, J = 7.2 Hz, 3H).…”

Section: Methodsmentioning

confidence: 99%

Single-Isomer Trisubstituted Olefins from a Novel Reaction of (E)-β-Chloro-α-iodo-α,β-unsaturated Esters and Amides

Simard-Mercier

Jiang

et al. 2008

J. Org. Chem.

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(E)-beta-chloro-alpha-iodo-alpha,beta-unsaturated esters are converted to single isomer trisubstituted olefins bearing three different carbon substituents by cross-coupling under reflux. Mechanistic investigations suggest that this process transfers a hydrogen from the boronic acid to the alpha-position of the substrate and then introduces an aryl group to the beta-position of the intermediate template while replacing chloride. The reaction is highly stereoselective, showing preference for the E-isomer. The process proceeds through (E)-beta-chloro-alpha-aryl-alpha,beta-unsaturated esters that are transformed efficiently into the corresponding E-products through stereoselective Suzuki-type reactions giving single isomers. The observed stereochemistry is apparently enabled by the intermediacy of a palladium allenoate. The reaction involves a catalytic cycle in which Pd(II) is reduced to Pd(0) through the formation of biaryl-coupled products.

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“…It has been established [4] that design of the 1,4-dihydropyridine-2(3H)-thione ring is a very complicated problem, since these compounds are readily oxidized in dilute solutions (compound 1d cannot be obtained by method D). We need to find conditions allowing them to be rapidly separated from the reaction medium or transformed to more stable 2-alkylthio-1,4-dihydropyridines, which is possible when using methods A-C. On the other hand, 2-arylideneacetoacetic acid ethyl esters, obtained from an aromatic aldehyde and acetoacetic acid ethyl ester (the starting materials for method A), are formed as a mixture of cis and trans isomers [9], and their separation is occasionally prolonged and labor-intensive, since upon heating the products of further Michael reaction are formed with participation of acetoacetic acid ethyl ester as the methylene component. The lacrimators 3-aryl-2-cyanothioacrylamides, obtained from an aromatic aldehyde and 2-cyanothioacetamide (the starting materials for method B), tend toward dimerization in the presence of bases [10].…”

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confidence: 99%

Synthesis, Structure, and Electrochemical Characteristics of 4-Aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-1,4-dihydropyridine-3-carboxylic Acid Nitriles

Баумане

Krauze

Belyakov

et al. 2005

Chem Heterocycl Compd

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Keywords: 1,4-dihydropyridines, hydrogen bond, one-pot multicomponent method, electrochemical oxidation, X-ray diffraction analysis.Nitriles of 2-alkylthio-4-aryl-1,4-dihydropyridine-3-carboxylic acids are of interest as potential antioxidants [1,2] that are also distinguished by cardiovascular [3,4] and hepatoprotective [5] activity.Continuing a study of the chemical and electrochemical properties of 2-alkylthio-1,4-dihydropyridines [4, 6] and methods for obtaining them [7,8], we have synthesized a series of novel 4-aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-6-methyl-1,4-dihydropyridine-3-carboxylic acid nitriles 1, in which we varied the substituents on the 4-phenyl ring over a broad range. We carried out a comparative analysis of the capability for electrochemical oxidation of 2-alkylthio-4-aryl-5-ethoxycarbonyl-1,4-dihydropyridine-3-carboxylic acid nitriles 1 and 4 as a function of the electronic properties of the aryl substituent on the 4 position of the heterocycle and the 2-alkylthio substituent, since the corresponding values of the potentials quantitatively characterize the antioxidant properties of the compounds. The electrochemical oxidation data were used for a more targeted search for biologically active substances. _______ * Dedicated to Academician V. Minkin to show our appreciation for his contribution to organic chemistry and his wonderful humanity, remembering his collaboration with his colleagues from Riga. _________________________________________________________________________________________

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Selective .gamma.-substitution of .alpha.,.beta.-unsaturated esters via .alpha.-trimethylsilyl .beta.,.gamma.-unsaturated esters

Cited by 43 publications

References 0 publications

Cadmium chloride mediated regiocontrol of dienolates and ketene thioacetals: γ condensation with aldehydes

Cadmium chloride mediated regiocontrol of dienolates and ketene thioacetals: γ condensation with aldehydes

Single-Isomer Trisubstituted Olefins from a Novel Reaction of (E)-β-Chloro-α-iodo-α,β-unsaturated Esters and Amides

Synthesis, Structure, and Electrochemical Characteristics of 4-Aryl-2-carbamoylmethylthio-5-ethoxycarbonyl-1,4-dihydropyridine-3-carboxylic Acid Nitriles

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