Aerobic Oxidations of Conjugated Dienes Using a Catalytic Palladium(II)−Quinone−Heteropolyacid System for Electron Transfer from Organic Substrates to Molecular Oxygen

Bergstad, Katarina; Grennberg, Helena; Bäckvall, Jan‐E.

doi:10.1021/om970482w

Cited by 57 publications

(22 citation statements)

References 42 publications

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“…The stoichiometric redox reaction between the Pd 0 complex 1 and biscarbonate 5 with formation of diene 8 and the Pd II complex 7 is mechanistically different from the Pd 0 ‐catalyzed elimination of allylic monocarbonates, which also yields 1,3‐dienes 41. 42 It is interesting to note that the reverse transformation to the one depicted in Scheme , the generation of 1,4‐bisacyloxycycloalk‐2‐enes and a Pd 0 complex from the corresponding 1,3‐cycloalkadienes and a Pd II complex, is well established 43…”

Section: Resultsmentioning

confidence: 99%

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Wang

Shao

et al. 2003

Chemistry A European J

106

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A general method has been developed to control the selective rearrangement of Meijer's AADD quadruply hydrogen-bonded homodimers by introducing an additional donor-acceptor interaction. Therefore, one donor-assembling monomer, 1, in which the electron-rich bis(p-phenylene)-34-crown-10 moiety is connected to the hydrogen-bonding moiety, and two acceptor-assembling monomers, 2 and 3, in which the electron-deficient pyromellitic diimide or naphthalene diimide group is incorporated, respectively, are synthesized and characterized. 1H NMR and 2D-NOESY studies show that all these compounds exist as stable homodimers in chloroform. Mixing 1 equiv of 1 with 1 equiv of 2 in chloroform leads to the formation of heterodimers 1.2 in approximately 60 % yield, as a result of the electrostatic interaction between the bis(p-phenylene)-34-crown-10 moiety of 1 and the pyromellitic diimide group of 2. Selective formation of heterodimer 1.3 (>97 %) was achieved by mixing 1 equiv of 1 with 1 equiv of 3 in chloroform which resulted in a strengthened electrostatic interaction between the bis(p-phenylene)-[34]crown-10 moiety of 1 and the naphthalene diimide group of 3. The structures of heterodimers 1.2 and 1.3, which have been characterized by 1H NMR and UV/Vis experiments, reveal a remarkable promoting effect between the donor-acceptor interaction and intermolecular hydrogen-bonding. 1H NMR studies also reveal that heterodimers 1.2 and 1.3 can be fully and partially dissociated by addition of heterocycle 29, leading to the formation of new more robust heterodimers 1.29 and 2.29, or 3.29,respectively, and partially regenerated by subsequent addition of heterocyclic compound 30 through the formation of a new heterodimer 29.30. Heterodimers 1.2 and 1.3 represent a novel class of pseudo[2]rotaxanes constructed by two different noncovalent interactions.

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Section: Resultsmentioning

confidence: 99%

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Wang

Shao

et al. 2003

Chemistry A European J

106

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“…[41,42] It is interesting to note that the reverse transformation to the one depicted in Scheme 12, the generation of 1,4-bisacyloxycycloalk-2-enes and a Pd 0 complex from the corresponding 1,3-cycloalkadienes and a Pd II complex, is well established. [43] According to NMR spectroscopy, the reaction of equimolar amounts of 1 and biscarbonates 5 b-d gave stoichiometric amounts of the corresponding dienes Isolation of complex 7 in allylic alkylation: Despite the many applications the Pd 0 complex 1 has found in asymmetric allylic alkylation, a recycling of the catalyst, which would be desirable because of the price of [Pd 2 A C H T U N G T R E N N U N G (dba) 3 ]·CHCl 3 and ligand 2, has not been described. The main obstacle to a recovery of 1 in allylic alkylation is the facile oxidation of the complex to the Pd II complex 7 by dioxygen.…”

Section: Resultsmentioning

confidence: 99%

Redox Reaction of the Pd⁰ Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato Pd^II Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation

Tsarev

Wolters

Gais

2010

Chemistry A European J

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The Pd(0) complex 1 that bears the Trost ligand 2 undergoes a facile redox reaction with 1,4-biscarbonates 5b-d and rac-22 under formation of the diamidato-Pd(II) complex 7 and the corresponding 1,3-cycloalkadienes 8b-d. The redox deactivation of complex 1 was the dominating pathway in the reaction of 5b-d with HCO(3)(-) at room temperature. However, at 0 degrees C the six-membered biscarbonate 5b, catalytic amounts of complex 1, and HCO(3)(-) mainly reacted in an allylic alkylation, which led to a highly selective desymmetrization of the substrate and gave alcohol 6b with > or = 99% ee in 66% yield. An increase of the catalyst loading in the reaction of 5b with 1 and HCO(3)(-) afforded the bicyclic carbonate 12b (96% ee, 92%). Formation of carbonate 12b involves two consecutive inter- and intramolecular substitution reactions of the pi-allyl-Pd(II) complexes 16b and 18b, respectively, with O-nucleophiles and presumably proceeds through the hydrogen carbonate 17b as key intermediate. The intermediate formation of 17b is also indicated by the conversion of alcohol rac-6b to carbonate 12b upon treatment with HCO(3)(-) and 1. The Pd(0)-catalyzed desymmetrization of 5b with formation of 12b and its hydrolysis allow an efficient enantioselective synthesis of diol 13b. The reaction of the seven-membered biscarbonate 5c with ent-1 and HCO(3)(-) afforded carbonate ent-12c (99% ee, 39%). The Pd(0) complex 1 is stable in solution and suffers no intramolecular redox reaction with formation of complex 7 and dihydrogen as recently claimed for the similar Pd(0) complex 9. Instead, complex 1 is rapidly oxidized by dioxygen to give the stable Pd(II) complex 7. Thus, formation of the Pd(II) complex 10 from 9 was most likely due to an oxidation by dioxygen. Oxidative workup (air) of the reaction mixture stemming from the desymmetrization of 5c catalyzed by 1 gave the Pd(II) complex 7 in high yield besides carbonate 12c.

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“…[12] There, however, the primary function of the quinone was to act as a coordinating and activating ligand to the palladium(ii) center and as an electron transfer mediator. The use of quinones as co-catalyst was tested in two reaction modes.…”

Section: Resultsmentioning

confidence: 99%

Quinones as Co-Catalysts and Models for the Surface of Active Carbon in the Phosphovanadomolybdate-Catalyzed Aerobic Oxidation of Benzylic and Allylic Alcohols: Synthetic, Kinetic, and Mechanistic Aspects

2000

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Quinones have been considered as reactive compounds present on the surface of active carbon. Thus, the co-catalytic use of quinones combined with the phosphovanadomolybdate polyoxometalate, PV2Mo10O40(5-), has been studied as an analogue of the known PV2Mo10O405-/C catalyst in oxidative dehydrogenation reactions. From the synthetic point of view both biphasic the quinone (org)-Na5PV2Mo10O40- (aq) and monophasic quinone (org)- 4Q5PV2Mo10O40-(org) [4Q = (nC4H9)4-N+] systems are effective for the selective oxidation of benzylic and allylic alcohols to their corresponding aldehydes. Kinetic measurements carried out on the model oxidative dehydrogenation of 4-methylbenzyl alcohol in the presence of p-chloranil, 4Q5PV2Mo10O40, and molecular oxygen showed that the reaction was non-elementary, although the 4-methylbenzyl alcohol oxydehydrogenation was the rate-determining step. ESR measurements showed the presence of the semiquinone of p-chloranil, probably as a complex with the polyoxometalate. This proposed complex was shown to be a more potent oxidant than p-chloranil. Thus, for the oxidation of 4-methoxytoluene the semiquinone complex was active, whereas p-chloranil alone was inactive. Beyond the importance of understanding quinone-phosphovanadomolybdate polyoxometalate-catalyzed reactions, insight gained from the formation of semiquinone active species can be applied for heterogeneous and aerobic oxidative transformations catalyzed by PV2Mo10O405- with carbon matrices as active supports.

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Aerobic Oxidations of Conjugated Dienes Using a Catalytic Palladium(II)−Quinone−Heteropolyacid System for Electron Transfer from Organic Substrates to Molecular Oxygen

Cited by 57 publications

References 42 publications

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Redox Reaction of the Pd⁰ Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato Pd^II Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation

Quinones as Co-Catalysts and Models for the Surface of Active Carbon in the Phosphovanadomolybdate-Catalyzed Aerobic Oxidation of Benzylic and Allylic Alcohols: Synthetic, Kinetic, and Mechanistic Aspects

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Aerobic Oxidations of Conjugated Dienes Using a Catalytic Palladium(II)−Quinone−Heteropolyacid System for Electron Transfer from Organic Substrates to Molecular Oxygen

Cited by 57 publications

References 42 publications

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Selective Rearrangements of Quadruply Hydrogen‐Bonded Dimer Driven by Donor–Acceptor Interaction

Redox Reaction of the Pd0 Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato PdII Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation

Quinones as Co-Catalysts and Models for the Surface of Active Carbon in the Phosphovanadomolybdate-Catalyzed Aerobic Oxidation of Benzylic and Allylic Alcohols: Synthetic, Kinetic, and Mechanistic Aspects

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Redox Reaction of the Pd⁰ Complex Bearing the Trost Ligand with meso‐Cycloalkene‐1,4‐biscarbonates Leading to a Diamidato Pd^II Complex and 1,3‐Cycloalkadienes: Enantioselective Desymmetrization Versus Catalyst Deactivation