24402-95-7Relevant articles and documents
Diels-Alder Reaction in Water. Effects of Hydrophobicity and Hydrogen Bonding
Otto, Sijbren,Blokzijl, Wilfried,Engberts, Jan B. F. N.
, p. 5372 - 5376 (1994)
In order to check whether the activated complex for the Diels-Alder reactions of 5-substituted 1,4-naphthoquinones 1a-e with cyclopentadiene (2) is more polar in water than in other solvents, we have determined the substituent effects in seven different solvents.The substituent effects gradually decrease with increasing rate of the reaction in a specific solvent, indicating that the charge separation in the activated complex in water is not much different from that in the other solvents.We also compared solvent effects on the Diels-Alder reaction of methyl vinyl ketone (3) with cyclopentadiene with effects on the corresponding reaction of methyl vinyl sulfone (4).The medium effects were separated into effects on initial state and activated complex.The destabilization of the initial state by water and the stabilization of the activated complex by 2,2,2-trifluoroethanol were less pronounced for the sulfone than for the ketone.These results further underline the importance of enforced hydrophobic interactions and changes in hydrogen bonding during the activation process in explaining the acceleration of Diels-Alder reactions in water.
Specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions in aqueous media
Mubofu, Egid B.,Engberts, Jan B.F.N.
, p. 180 - 186 (2004)
A comparative study of specific acid catalysis and Lewis acid catalysis of Diels-Alder reactions between dienophiles (1, 4 and 6) and cyclopentadiene (2) in water and mixed aqueous media is reported. The reactions were performed in water with copper(II) nitrate as the Lewis acid catalyst whereas hydrochloric acid was employed for specific acid catalysis. At equimolar amounts of copper(II) nitrate and hydrochloric acid (0.01 M, for example) and under the same reaction conditions, the reaction rate for 1a with 2 is about 40 times faster with copper catalysis than with specific acid catalysis. Moreover, at 32°C and 0.01 M HCl, the reaction of 1b with 2 is about 21 times faster than the same uncatalyzed reaction in pure water under the same reaction conditions. The inverse solvent kinetic isotope effect shows that these Diels-Alder reactions undergo specific acid catalysis. Copyright
Lewis acid catalyst system for Diels–Alder reaction
Kalepu, Rishir,Mishra, Satyendra
, (2020/03/06)
Abstract: Ca(OTf)2/Bu4NPF6 catalytic system has been illustrated for the synthesis of Diels–Alder adduct for the first time. This procedure tolerates substrate diversity and delivers high yield. Use of environmentally benign catalyst, high yields and substrate diversity are the highlight of the existing method. Graphic Abstract: Ca(OTf)2, along with n-Bu4NPF6 as the co-catalyst, is shown to be an effective Lewis acidic catalyst system for the Diels–Alder reaction. Apart from being sustainable and efficient, this procedure is robust and products are obtained in near-quantitative yields.[Figure not available: see fulltext.].
Design, synthesis and evaluation of small molecule reactive oxygen species generators as selective Mycobacterium tuberculosis inhibitors
Dharmaraja, Allimuthu T.,Alvala, Mallika,Sriram, Dharmarajan,Yogeeswari, Perumal,Chakrapani, Harinath
supporting information, p. 10325 - 10327 (2012/11/13)
Here, we report 5-hydroxy-1,2,3,4,4a,9a-hexahydro-1,4-ethano-9,10- anthraquinone (13), a small molecule generating reactive oxygen species (ROS) in pH 7.4 buffer under ambient aerobic conditions that has selective and potent Mycobacterium tuberculosis gro