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1.
A short synthesis of the title compound 13 is reported. The acetal group in 13 enables one to control the regio- and stereoselectivity of the two successive Diels-Alder additions of the tetraene. The first addition is significantly faster than the second one, thus making 13 a versatile reagent for regio- and stereoselective ‘tandem’ cycloadditions. 相似文献
2.
《Tetrahedron》2003,59(4):481-492
The synthesis of the new dienes N-substituted 2,3,4,5-tetrahydrobenzoxazol-2-ones 8a-8c is described, through a one-step convergent process from 1,2-cyclohexanedione (7a) and the corresponding isocyanates 2a-2c. The presence of electron-donor substituents in the aryl ring of the isocyanate gave rise to the exclusive formation of the captodative olefins 10. Diene 8a proved to be reactive and stereoselective in Diels-Alder additions with a cyclic olefin. The reaction with acetylenic dienophiles yielded the 2,3-dihydrobenzoxazol-2-ones 21 and 24, as the products of sequential [4+2] cycloaddition and retro-Diels-Alder reactions. Methyl vinyl ketone (22) underwent regio- and stereoselective tandem Diels-Alder and Michael additions to give propellane 29a. Evidence of an endo π-pyramidalization of the central double bond of adduct 19 would rationalize the exo stereoselection in the formation of 29a. The regioselectivity in these reactions has been rationalized in terms of FMO theory by ab initio calculations. 相似文献
3.
《合成通讯》2013,43(20):3643-3650
Abstract A one-pot preparation of 2,5-dihydrothiophene-1,1-dioxide-3-carboxylic acid (3-sulfolene-3-carboxylic acid) is reported. The carboxylation of 3-sulfolene, exclusively at the 3-position, using CO2 and DBU proceeds to >90% conversion. A rapid workup gives 3-sulfolene-3-carboxylic acid, a stable precursor to 1,3-butadiene-2-carboxylic acid. High conversions to Diels-Alder adducts were obtained upon treatment of 3-sulfolene-3-carboxylic acid with various dienophiles. 相似文献
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[structures: see text] A stereoselective synthesis of 2,3,5,6-tetra- and 2,3,4,5,6-pentasubstituted piperidines was achieved from oxidative cleavage of 2-aza-bicyclo[2.2.2]octene Diels-Alder adducts derived from N-protected 2-methyl-1,2-dihydropyridine. A chiral auxiliary mediated asymmetric synthesis of the pentasubstituted piperidine is also demonstrated. This methodology incorporates orthogonal protecting groups, thus providing a piperidine scaffold with easily modified points of diversity. 相似文献
6.
2,3,5,6-Tetrabromopyridines with 4-mercapto, 4-chlorosulfenyl, and 4-chlorosulfonyl groupings were synthesized, and some of their reactions were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1514–1518, November, 1978. 相似文献
7.
Compain-Batissou M Latreche D Gentili J Walchshofer N Bouaziz Z 《Chemical & pharmaceutical bulletin》2004,52(9):1114-1116
Oxidation of 2- and 3-hydroxycarbazoles with Frémy's salt gave the corresponding ortho-carbazolequinones. These molecules react as carbodienophiles in Diels-Alder reaction with 1-acetoxy-1,3-butadiene and 1,3-cyclopentadiene to provide the novel benzocarbazolequinone structures 15, 16, 18 and 19. 相似文献
8.
2,3-Dimethylidenebicyclo [2.1.1]hexane (4) was isolated from direct irradiation (253.7 nm) of 5,6-dimethylidene-2-norbornanone (3) . Quenching experiments at 253.7 nm, as well as direct and sensitized irradiations at >300 nm suggested that a high vibrationally excited S1- or a S2-state is required for the photodecarbonylation of 3 in contrast with other β, γ-unsaturated ketones for which α-cleavage occurs with lower excitation-energy. The new diene 4 reacted toward tetracyano-ethylene (k (1mol?1 s?1))=(3.1±0.34) · 10?3) in toluene and (6.2±0.11) · 10?3 in benzene only 60 times more slowly than 2,3-dimethylidenenorbornane (5) and ca. 850 times as fast as 2,3-dimethylidene-syn1,4,5,6-tetramethylbicyclo[2.1.1]-hexane (9) . 相似文献
9.
Toshiyuki OhfusaAtsushi Nishida 《Tetrahedron》2011,67(10):1893-1906
Several bicyclic compounds were synthesized by the Diels-Alder reaction using aminodiene and a cyclic dienophile. The stereochemistries of the obtained adducts were determined by X-ray crystallography or NMR analysis. The stereoselectivity of this Diels-Alder reaction was based on the interaction of molecular orbitals between the diene and dienophile. The reactivities of these Diels-Alder reactions were estimated, and the generality of this reaction is discussed. 相似文献
10.
Biphenylcarboxylic acid derivatives, and some tetracyclic bridge cycloadducts have been prepared by Diels-Alder reactions of acetylenic and olefinic dienophiles with 4-hydrpxy-6-phenyl-2H-pyran-2-one and its methyl ether derivative. 相似文献
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13.
Ulrich Hnisch Enrico Tagliaferri Raymond Roulet Pierre Vogel 《Helvetica chimica acta》1983,66(7):2182-2190
Treatment of [2.2.2]hericene 10 with Fe2(CO)9 in hexane gave a mixture of monometallic complex 14 , two isomeric dimetallic complexes 15 and 16 , and a trimetallic complex 19 in which all the three diene moieties of 10 , are coordinated. The rate constants of the Diels-Alder additions of tetracyanoethylene (TCE) and dimethyl acetylenedicarboxylate (DMAD) to the uncomplexed diene moieties of 14–16 have been evaluated and compared with those measured for the uncomplexed 10 and its monoadducts 11A, 11B and bis-adducts 12A, 12B. The tricarbonyldieneiron function retards the cycloaddition of an homoconjugated, exocyclic s-cis-butadiene. The effect is significantly larger for TCE- than for DMAD-additions. The origin of this effect is discussed briefly in terms of the valence-bond model which is usually assumed to describe the properties of a tricarbonyldieneiron complex, and in terms of the inductive and steric factors of the Fe(CO)3-group. 相似文献
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15.
[structure in text] The synthesis of several 4-vinylimidazoles via Stille cross-coupling reactions of the corresponding protected 4-iodoimidazoles with tributylvinylstannane is described. These heterocyclic dienes are shown to be effective partners in the Diels-Alder reaction, providing adducts in good yield and exhibiting useful levels of isomer selectivity and stereoselectivity (endo/exo). 相似文献
16.
Robert T. Paine William F. McNamara Jerzy Fr. Janik Eileen N. Duesler 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-2):241-244
Abstract Aspects of the reactivity of metallophosphanes are presented along with the synthesis and structure determinations for new aluminophosphanes. 相似文献
17.
W. Güth E. Niecke H. Westermann 《Phosphorus, sulfur, and silicon and the related elements》2013,188(3-4)
Abstract Synthetic routes to various aminodiphosphanes 1 are reported. 相似文献
18.
Cyril Mahaim Pierre-Alain Carrupt Jean-Pierre Hagenbuch Andr Florey Pierre Vogel 《Helvetica chimica acta》1980,63(5):1149-1157
Palladium-catalyzed double carbomethoxylation of the Diels-Alder adduct of furan and maleic anhydride yielded the methyl all-exo-7-oxanorbornane-2,3,5,6-tetracarboxylate (7) which was transformed in three steps into 2,3,5,6-tetramethylidene-7-oxanorbornane (1) , a useful synthon. Six isomeric methyl 7-oxanor-bornane-2,3,5,6-tetracarboxylates (7–12) have been isolated and their 1H- and 13C-NMR. data are compared. 相似文献
19.
Yamauchi M Honda Y Matsuki N Watanabe T Date K Hiramatsu H 《The Journal of organic chemistry》1996,61(8):2719-2725
The Diels-Alder reaction of 1,1-dicarbonylethenes 1 with dienes was investigated. The adduct of the reaction of 1, whose two carbonyl groups were different, with cyclopentadiene showed moderate stereoselectivity and this was explained by FMO theory. However, in the Lewis acid-catalyzed addition, the reaction proceeded with high stereoselectivity to give the exo adduct 3x. This might be due to steric hindrance because the benzene ring cannot orient in the plane of the conjugated system in the metal-chelated enedione 6. Applying this principle to (1'R,2'S,5'R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 2-benzoylacrylate (1d), we achieved a diastereomeric Diels-Alder reaction to afford 3x-R, whose structure was confirmed by the X-ray crystal analysis. 相似文献
20.
Pascal Vermeeren Marco Dalla Tiezza Michelle van Dongen Prof. Dr. Israel Fernández Prof. Dr. F. Matthias Bickelhaupt Dr. Trevor A. Hamlin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(41):10610-10620
The catalytic effect of various weakly interacting Lewis acids (LAs) across the periodic table, based on hydrogen (Group 1), pnictogen (Group 15), chalcogen (Group 16), and halogen (Group 17) bonds, on the Diels-Alder cycloaddition reaction between 1,3-butadiene and methyl acrylate was studied quantum chemically by using relativistic density functional theory. Weakly interacting LAs accelerate the Diels-Alder reaction by lowering the reaction barrier up to 3 kcal mol−1 compared to the uncatalyzed reaction. The reaction barriers systematically increase from halogen<hydrogen<chalcogen<pnictogen-bonded LAs, i. e., the latter have the least catalytic effect. Our detailed activation strain and Kohn-Sham molecular orbital analyses reveal that these LAs lower the Diels-Alder reaction barrier by increasing the asynchronicity of the reaction to relieve the otherwise destabilizing Pauli repulsion between the closed-shell filled π-orbitals of diene and dienophile. Notably, the reactivity can be further enhanced on going from a Period 3 to a Period 5 LA, as these species amplify the asynchronicity of the Diels-Alder reaction due to a stronger binding to the dienophile. These findings again demonstrate the generality of the Pauli repulsion-lowering catalysis concept. 相似文献