- Diels-Alder Reactions in Hydrophobic Cavities: a Quantitative Correlation with Solvophobicity and Rate Enhancements by Macrocycles
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Based on the relaction of cyclopentadiene with diethyl fumarate a linear correlation of log k vs. solvophobicity parameters is reported as well as saturation kinetics showing up to 70-fold rate increase by complexation in β-cyclodextrin.
- Schneider, Hans-Joerg,Sangwan, Naresh K.
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- Liquid coordination complexes of Lewis acidic metal chlorides: Lewis acidity and insights into speciation
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Coordination complexes of Lewis acidic metal chlorides AlCl3, GaCl3, InCl3, SbCl3, SnCl4, SnCl2, ZnCl2 and TiCl4 with trioctylphosphine (P888) and trioctylphosphine oxide (P888O) were synthesised. All compounds formed liquid coordination complexes (LCCs) at ambient temperature, although decomposition via a redox mechanism was detected in some cases. The Lewis acidity of the metal chlorides (measured in 1,2-dichloroethane solutions) and the LCCs (measured neat) was quantified by using the Gutmann acceptor number (AN) approach. In general, LCCs were equally or more Lewis acidic than the corresponding metal chlorides. The AN values were compared with the catalytic activity of selected LCCs in a model Diels-Alder reaction. Insight into speciation of LCCs was gained using multinuclear NMR spectroscopy, revealing that most LCCs comprised charge-neutral complexes rather than ionic ones. The relationship between the speciation, Lewis acidity (AN scale) and catalytic activity is discussed in detail. This approach reveals several new, promising catalytic systems, such as P888O-InCl3, with Lewis acidity enhanced compared to chloroindate ionic liquids, and P888O-TiCl4, with hydrolytic stability enhanced with respect to neat TiCl4.
- Hogg, James M.,Brown, Lucy C.,Matuszek, Karolina,Latos, Piotr,Chrobok, Anna,Swad?ba-Kwa?ny, Ma?gorzata
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- Planar chiral PHANOLS as organocatalysts for the Diels-Alder reaction via double hydrogen-bonding to a carbonyl group
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Planar chiral PHANOLs have been shown to catalyze Diels-Alder reactions of α,β-unsaturated aldehydes and ketones with various dienes. Rate accelerations of up to ca. 30-fold were obtained using the electron deficient 4,12-dihydroxy-7,15-dinitro[2.2]paracyclophane as a catalyst. It is proposed that the carbonyl group of the dienophile is activated via a double hydrogen-bonding mode. Although the PHANOLs are inherently chiral, little or no asymmetric induction was observed when using enantiopure (R)-PHANOL.
- Braddock, D. Christopher,MacGilp, Iain D.,Perry, Benjamin G.
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- Diels-Alder reactions are faster in water than in ionic liquids at room temperature
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(Chemical Equation Presented) Nobody does it better: A comparative study indicates that water, rather than room-temperature ionic liquids (RTILs), is still the solvent of choice for accelerating Diels-Alder reactions. Both the hydrogen-bonding ability and the viscosity of the solvent are thought to play a role.
- Tiwari, Shraeddha,Kumar, Anil
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- Studies on the use of surfactants in aqueous Diels-Alder reactions
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The effects of added surfactants on the aqueous Diels-Alder reaction between cyclopentadiene and a range of acrylate esters have been studied. The surfactants were used at their critical micellar concentrations, and the pH of the aqueous solutions was varied to determine the optimum conditions for the formation of the endo cycloadduct.
- Diego-Castro,Hailes
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- Synthesis of saturated bicyclic diesters
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Bicyclic saturated diesters were synthesized by the catalytic addition of monobasic saturated acids to unsaturated bicyclic esters. A possible mechanism of the reaction was proposed.
- Mamedov,Kadyrly
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- Selective complexation of 2-hydroxyethyl esters using Lewis acids
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Competitive Diels-Alder reactions between ethyl acrylate and 2- hydroxyethyl acrylate (1,3-cyclopantadiene, CH2Cl2, 0°C) in the presence of a variety of Lewis acids indicate that selective complexation of the 2- hydroxyethyl ester can be accomplished, most notably using EtAlCl2. Further Diels-Alder reactions using ethyl 2-hydroxyethyl fumarate support these findings. 13C NMR studies provide direct evidence for the nature of the interactions between 2-hydroxyethyl esters and EtAlCl2.
- Clapham, Gary,Shipman, Michael
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- Asymmetric induction of cyclopentadiene in the Diels-Alder reaction on acrylic derivatives of arabinose and ribose O-methylene acetals
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The acrylates of methyl β-D-arabinopyranoside and methyl β-D-ribofuranoside protected respectively as 3,4- and 2,3-O-methyleneacetals have been used as chiral templates in the asymmetric Diels-Alder reaction with cyclopentadiene. Sugar moieties are very stable towards Lewis acids and the arabinose derivative is very efficient for asymmetric induction.
- Nouguier,Gras,Giraud,Virgili
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- Oxathiaborolium-Catalyzed Enantioselective [4 + 2] Cycloaddition and Its Application in Lewis Acid Coordinated and Chiral Lewis Acid Catalyzed [4 + 2] Cycloaddition
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The nascency of second-generation sulfur-stabilized borenium cations by halophilic Lewis acid SnCl4 leads to highly active chiral Lewis acids that are very effective catalysts for [4 + 2] cycloaddition. Oxathiaborolium pentachlorostannate (5-10 mol %) successfully catalyzed cycloaddition of various dienes and dienophiles to afford cycloadducts with excellent enantioselectivity (20 examples, up to 99% ee). This super Lewis acid also exhibited good enantioselectivity for the first Lewis acid coordinated and chiral Lewis acid catalyzed [4 + 2] cycloaddition to α,β-unsaturated mixed ester amide.
- Boobalan, Ramalingam,Chein, Rong-Jie
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supporting information
p. 6760 - 6764
(2021/09/11)
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- Design and Development of Highly Potent HIV-1 Protease Inhibitors with a Crown-Like Oxotricyclic Core as the P2-Ligand To Combat Multidrug-Resistant HIV Variants
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Design, synthesis, and evaluation of a new class of exceptionally potent HIV-1 protease inhibitors are reported. Inhibitor 5 displayed superior antiviral activity and drug-resistance profiles. In fact, this inhibitor showed several orders of magnitude improved antiviral activity over the FDA approved drug darunavir. This inhibitor incorporates an unprecedented 6-5-5 ring-fused crown-like tetrahydropyranofuran as the P2 ligand and an aminobenzothiazole as the P2′ ligand with the (R)-hydroxyethylsulfonamide isostere. The crown-like P2 ligand for this inhibitor has been synthesized efficiently in an optically active form using a chiral Diels-Alder catalyst providing a key intermediate in high enantiomeric purity. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors.
- Ghosh, Arun K.,Rao, Kalapala Venkateswara,Nyalapatla, Prasanth R.,Osswald, Heather L.,Martyr, Cuthbert D.,Aoki, Manabu,Hayashi, Hironori,Agniswamy, Johnson,Wang, Yuan-Fang,Bulut, Haydar,Das, Debananda,Weber, Irene T.,Mitsuya, Hiroaki
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p. 4267 - 4278
(2017/06/05)
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- Functional norbornanyl ester derivatives, polymers and process for preparing same
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This invention relates to the new functional norbornanyl ester derivative and/or polymer compositions which are easily obtainable by reacting the Diels-Alder adduct of appropriate dienes and dienophiles with carboxylic acids. In particular, this invention relates to a new process for making cyclic chemical raw materials suitable for production coating, ink, adhesive, plasticizer, thermoplastic or thermosetting plastic and functional polymers.
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Paragraph 0196
(2013/12/04)
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- LiAlH4-induced reductive dephosphonylation of αα-dialkyl triethyl β-phosphonyl esters: Mechanistic study and synthetic application
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Treatment of αα-dialkyl triethyl β-phosphonyl esters with LiAlHin CHlTHF caused the one-pot dephosphonylation and reduction to yield the corresponding primary alcohols bearing a controllable β secondary carbon center. Mechanistic study has revealed that the LiAlHinduced dephosphonylation should occur first with the assistance of the carboxylate group, and the hydrogen source of the resultant new C-H bond is LiAlH. Georg Thieme Verlag Stuttgart . New York.
- Zhu, Jia-Liang,Bau, Jr-Sheng,Shih, You-Cheng
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experimental part
p. 863 - 866
(2012/05/20)
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- Asymmetric Diels-Alder reaction between acrylates and cyclopentadiene in the presence of chiral catalysts
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Asymmetric Diels-Alder reaction between cyclopentadiene and alkyl and cycloalkyl acrylates in the presence of new chiral catalysts, BBr 3?MentOEt, AlCl2OMent, BBr2OMent, and BBr(OMent)2, was studied. Optically active bicyclo[2.2.1]hept-2-ene- 5-carboxylates were synthesized. The influence of the reaction conditions on the total and optical yields and on the stereoselectivity of the adducts synthesized was examined. Nauka/Interperiodica 2006.
- Mamedov
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p. 1621 - 1625
(2008/02/07)
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- Oxazaborolidine-derived Lewis acid assisted Lewis acid as a moisture-tolerant catalyst for enantioselective Diels-Alder reactions
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Reactive, selective, and tough, the chiral Lewis acid generated from 1 and SnCl4 catalyzes the enantioselective Diels-Alder reactions of various classes of substrates (see scheme). The reactive species preserves its asymmetric induction ability even in the presence of a large excess of SnCl 4. Importantly, this catalyst system is tolerant to a small amount of moisture, oxygen, and Lewis bases.
- Futatsugi, Kentaro,Yamamoto, Hisashi
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p. 1484 - 1487
(2007/10/03)
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- Alkyl-substituted tetracyclododecenecarboxylic acid esters, (meth)acrylic acid addition products thereof, and methods for producing the same
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The present invention provides alkyl-substituted tetracyclododecenecarboxylic acid esters presented by the general formula (I): wherein R1 is an alkyl group having 1 to 4 carbon atoms and R2 is a hydrocarbon group having 1 to 12 carbon atoms. Further, the represent invention provides (meth)acrylic acid addition products of alkyl-substituted tetracyclododecenecarboxylic acid esters represented by the general formula (II): wherein R1 is an alkyl group having 1 to 4 carbon atoms, R2 is a hydrocarbon group having 1 to 12 carbon atoms, and R3 is a hydrogen atom or a methyl group.
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- The Kinetic Effects of Water and of Cyclodextrins on Diels-Alder Reactions. Host-Guest Chemistry. Part 18
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The rates of 19 different dienophiles with mostly cyclopentadiene have been measured in a range of solvents.Water, by comparison with methanol, is found to accelerate the cycloadditions by factors ranging from 15-7 680.While there is no simple correlation of the rate enhancement with the hydrophobicity of the substrates, a correlation can be made in the case of acrylates, which show a decreasing rate effect due to water, and with β-cyclodextrin, which is found to lead to inhibition in these and several other cases.Computer analysis of enzyme-like saturation kinetics-observed with some fumarates in the presence of β-cyclodextrin-indicates apparent binding constants for the ternary complex of ca. 102 dm3 mol-1 and catalytic kcat/ko ratios of up to 100.Heptakis-6 piperidino-β-cyclodextrin in the form of its ammonium salt leads to rate retardation in most of the cases investigated; sodium dodecylsulphate also decreases the constants. α-Cyclodextrin generates small effects, rate retardation, or in one case complete inhibition.
- Sangwan, Naresh K.,Schneider, Hans-Joerg
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p. 1223 - 1228
(2007/10/02)
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- ASYMMETRIC DIELS-ALDER REACTIONS OF CHIRAL ALKOXY IMINIUM SALTS
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The optically active vinyl trimethylsilyloxy iminium salts, prepared from 8 and 14ab, were reacted with cyclopentadiene to give the optically active amides 15 and 16ab in high yield and with good diastereoselectivity.
- Jung, Michael E.,Vaccaro, Wayne D.,Buszek, Keith R.
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p. 1893 - 1896
(2007/10/02)
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- The Low-Temperature, Ionic Diels-Alder Addition of Vinyl Ortho Esters to 1,3-Dienes
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3,3,3-Triethoxypropene (triethyl orthoacrylate) was added to a series of 1,3-dienes in the presence of trimethylsilyl triflate at -78 to 0 deg C to produce 53-83percent yields of the adduct of ethyl acrylate and the 1,3-dienes.The products were formed und
- Gassman, Paul G.,Chavan, Subhash P.
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p. 2392 - 2394
(2007/10/02)
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