10138-32-6Relevant articles and documents
Diels-Alder Reactions in Hydrophobic Cavities: a Quantitative Correlation with Solvophobicity and Rate Enhancements by Macrocycles
Schneider, Hans-Joerg,Sangwan, Naresh K.
, p. 1787 - 1789 (1986)
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.
Liquid coordination complexes of Lewis acidic metal chlorides: Lewis acidity and insights into speciation
Hogg, James M.,Brown, Lucy C.,Matuszek, Karolina,Latos, Piotr,Chrobok, Anna,Swad?ba-Kwa?ny, Ma?gorzata
, p. 11561 - 11574 (2017)
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.
Planar chiral PHANOLS as organocatalysts for the Diels-Alder reaction via double hydrogen-bonding to a carbonyl group
Braddock, D. Christopher,MacGilp, Iain D.,Perry, Benjamin G.
, p. 1121 - 1124 (2003)
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.
Diels-Alder reactions are faster in water than in ionic liquids at room temperature
Tiwari, Shraeddha,Kumar, Anil
, p. 4824 - 4825 (2006)
(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.
Studies on the use of surfactants in aqueous Diels-Alder reactions
Diego-Castro,Hailes
, p. 2211 - 2214 (1998)
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.
Synthesis of saturated bicyclic diesters
Mamedov,Kadyrly
, p. 1132 - 1136 (2017)
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.
Selective complexation of 2-hydroxyethyl esters using Lewis acids
Clapham, Gary,Shipman, Michael
, p. 5639 - 5642 (1999)
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.
Asymmetric induction of cyclopentadiene in the Diels-Alder reaction on acrylic derivatives of arabinose and ribose O-methylene acetals
Nouguier,Gras,Giraud,Virgili
, p. 6245 - 6252 (1992)
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.
Oxathiaborolium-Catalyzed Enantioselective [4 + 2] Cycloaddition and Its Application in Lewis Acid Coordinated and Chiral Lewis Acid Catalyzed [4 + 2] Cycloaddition
Boobalan, Ramalingam,Chein, Rong-Jie
supporting information, p. 6760 - 6764 (2021/09/11)
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.
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
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
, p. 4267 - 4278 (2017/06/05)
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.
