Hydrophobic acceleration of Diels-Alder reactions

Rideout, Darryl; Breslow, Ronald

doi:10.1021/ja00546a048

Cited by 1,439 publications

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“…However, since Breslow´s work in early 1980s, [79] many studies have shown that the Diels-Alder reaction often proceeds faster and with higher selectivity in water than in organic medium. [80][81][82][83] The origin for the water rate acceleration effect, although lacking complete understanding, seems to relay mainly on two effects: enforced hydrophobic interactions and activation of the dienophile by hydrogen bonding with water molecules.…”

Section: Diels-alder Reactions In Aqueous Mediamentioning

confidence: 99%

“…These functions are expected to also display high cycloaddition reaction rates in aqueous media. [79,82] Nevertheless these functionalities are presumably more unstable under aqueous solutions than the acyclic diene, being gradually desactivated by dimerization. Therefore, the relation between reactivity and stability of the dienyl conjugates are two important issues to be investigated for the immobilization of proteins by Diels-Alder ligation.…”

Section: Immobilization Of Proteins On Glass Surfaces By Diels-alder mentioning

confidence: 99%

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Diels–Alder Ligation of Peptides and Proteins

Araújo

Palomo

Cramer

et al. 2006

Chemistry A European J

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Section: Diels-alder Reactions In Aqueous Mediamentioning

confidence: 99%

Section: Immobilization Of Proteins On Glass Surfaces By Diels-alder mentioning

confidence: 99%

Diels–Alder Ligation of Peptides and Proteins

Araújo

Palomo

Cramer

et al. 2006

Chemistry A European J

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“…[13] In aqueous medium, acceleration of the cycloaddition by water should outweigh the lowered efficiency and reaction rate due to the highly dilute reaction conditions. [9] In addition, water can induce rate enhancements, [14] chemoselectivity, [15] and stereoselectivity [16] in numerous synthetic transformations. However, to the best of our knowledge mixed solvents or photochemical activation were necessary in previous works, and the cycloaddition of diynes and a nitrile in neat water without irradiation has never been reported.…”

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confidence: 99%

Ruthenium‐catalyzed [2+2+2] Cycloaddition of Diynes with Nitriles in Pure Water

Wang

et al. 2012

ChemSusChem

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The transition metal-catalyzed [2+2+2] cycloaddition of two alkyne molecules and a nitrile, particularly involving catalysis by Co, Ru, Rh, Ni, Ti, and Fe species, [1][2][3][4][5][6] has been widely investigated as a valuable tool for the synthesis of substituted pyridines. [7,8] However, highly diluted conditions and techniques of slow addition are generally required to suppress the competing side reactions, such as dimerization and trimerization of the diynes. [9a] Despite substantial advances, metal-catalyzed [2+2+2] cycloaddition remains a formidable challenge. Thus, new tactics should be applied to the reaction, aimed at attenuating or controlling the side reactions. It has been shown that the Diels-Alder reaction can be intensified in aqueous media, [9b] and we expect that water can also expedite the [2+2+2] cycloaddition.Although the [2+2+2] cycloaddition reaction has been widely explored in the last few decades, there are only limited examples of the use of water as solvent (Scheme 1). Heller and co-workers reported that acetylene and nitriles in water efficiently undergo co-cyclization under visible-light irradiation in the presence of CpCo(COD) (COD: 1,5-cyclooctadiene) and its derivatives, resulting in excellent product selectivities and moderate yields. [10] Parsons and Jerome reported a reaction of hexyne and acetonitrile in supercritical water at 374 8C, affording the corresponding pyridine isomers in a yield of 15 %. [11] Eaton and co-workers showed that a water-soluble cobalt complex catalyzes the [2+2+2] cycloaddition of two alkyne molecules and a nitrile in a mixture of water and methanol at 85 8C, with a yield of up to 99 %. However, hydrophilic functional groups on the alkynes were necessary. [12] In 2002, Butenschçn reported another cobalt complex with pendant phosphane substituents on the cyclopentadienyl ring. These substituents made the cobalt complex stable in water, thus allowing the preparation of pyridine derivatives at room temperature in a mixture of water and ethanol. [13] In aqueous medium, acceleration of the cycloaddition by water should outweigh the lowered efficiency and reaction rate due to the highly dilute reaction conditions. [9] In addition, water can induce rate enhancements, [14] chemoselectivity, [15] and stereoselectivity [16] in numerous synthetic transformations. However, to the best of our knowledge mixed solvents or photochemical activation were necessary in previous works, and the cycloaddition of diynes and a nitrile in neat water without irradiation has never been reported. The development of a new catalytic system to circumvent these restrictions is still highly desirable.Generally, two crucial problems are encountered in the [2+2+2] cycloaddition of alkynes and nitriles in water: 1) the poor solubility of the metal precursor and substrates in pure water, and 2) easy hydrolysis of the nitriles in water under the reaction conditions. [17] To overcome these issues, we surmised that a water-soluble ligand might connect the metal precursor and substrates in th...

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“…The ease of workup and technical procedure, non-hazardous, shorter reaction time, non-polluted to the environment and good yields are the advantages of this reaction. 1,2,8,9 Rideout and Breslow 10 have studied the cycloaddition reaction of ethylenic ketones and cyclopentadiene in an aqueous medium and they reported the reaction rate is greater than 700 times faster than in non-aqueous media. Many catalysts such as Lewis acids, 5 Bronsted acids, 6,11 asymmetric helical polymers, 12 Cu 2+ ion-mediated nanotubes 13 and Micellar-DNAs 8, [13][14][15][16][17][18] have been employed for the Diels-Alder [4+2] cycloaddition reaction of cyclopentadiene (diene) and (E)-chalcones (dienophiles).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Evaluation of Biological Activities of Some 2-Hydroxy-1-Naphthyl Bicyclo [2.2.1] Heptene-2-Yl-Methanones

Thirunarayanan¹

2017

ECB

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Totally twelve ((2-hydroxy-1-naphthyl))(3-(substituted phenyl)bicyclo [2.2.1]hept-5-ene-2-yl)methanones have been synthesized by fly-ash catalyzed water-mediated Diels-Alder [4+2] cycloaddition reaction. The synthesized bicyclic ketones were characterized by their physical constants, analytical and spectroscopic data. The antimicrobial and antioxidant activities of these bicyclic methanones were evaluated using Bauer-Kirby disc diffusion and diphenyl picrylhydrazyl(DPPH) radical scavenging technique. Most of the bicyclic methanones showed good antibacterial and antifungal activities against their microbial strains. The hydroxy-and methoxy-substituted methanones shows significant antioxidant activity. *Corresponding Authors

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Hydrophobic acceleration of Diels-Alder reactions

Cited by 1,439 publications

References 0 publications

Diels–Alder Ligation of Peptides and Proteins

Diels–Alder Ligation of Peptides and Proteins

Ruthenium‐catalyzed [2+2+2] Cycloaddition of Diynes with Nitriles in Pure Water

Synthesis and Evaluation of Biological Activities of Some 2-Hydroxy-1-Naphthyl Bicyclo [2.2.1] Heptene-2-Yl-Methanones

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