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- 2019
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Jiang, Min, et al.
(författare)
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Palladium-Catalyzed Oxidative Diarylating Carbocyclization of Enynes
- 2012
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 14:13, s. 3538-3541
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Tidskriftsartikel (refereegranskat)abstract
- A mild and efficient palladium-catalyzed oxidative diarylating carbocyclization of enynes is described. The reaction tolerates a range of functionalized arylboronic acids to give diarylated products in good yields. Control experiments suggest that the reaction starts with an arylpalladation of the alkyne, followed by carbocyclization, transmetalation, and reductive elimination to afford the diarylated product.
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| 3. |
- Aad, G, et al.
(författare)
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- 2015
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swepub:Mat__t
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| 4. |
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| 5. |
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| 6. |
- Bartholomeyzik, Teresa, et al.
(författare)
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Kinetics and Mechanism of the Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes
- 2018
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 140:1, s. 298-309
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Tidskriftsartikel (refereegranskat)abstract
- Pd-catalyzed C-C bond-forming reactions under oxidative conditions constitute a class of important and widely used synthetic protocols. This Article describes a mechanistic investigation of the arylating carbocyclization of allenynes using boronic acids and focuses on the correlation between reaction conditions and product selectivity. Isotope effects confirm that either allenic or propargylic C-H activation occurs directly after substrate binding. With an excess of H2O, a triene product is selectively formed via allenic C-H activation. The latter C-H activation was found to be turnover-limiting and the reaction zeroth order in reactants as well as the oxidant. A dominant feature is continuous catalyst activation, which was shown to occur even in the absence of substrate. Smaller amounts of H2O lead to mixtures of triene and vinylallene products, where the latter is formed via propargylic C-H activation. The formation of triene occurs only in the presence of ArB(OH)(2). Vinylallene, on the other hand, was shown to be formed by consumption of (ArBO)(3) as a first-order reactant. Conditions with sub-stoichiometric BF3 center dot OEt2 gave selectively the vinylallene product, and the reaction is first order in PhB(OH)(2). Both C-H activation and transmetalation influence the reaction rate. However, with electron-deficient ArB(OH)(2), C-H activation is turnover-limiting. It was difficult to establish the order of transmetalation vs C-H activation with certainty, but the results suggest that BF3 center dot OEt2 promotes an early transmetalation. The catalytically active species were found to be dependent on the reaction conditions, and H2O is a crucial parameter in the control of selectivity.
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| 7. |
- Jiang, Tuo, et al.
(författare)
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Palladium-Catalyzed Oxidative Carbocyclization/Arylation of Enallenes
- 2011
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Ingår i: Organic Letters. - : American Chemical Society (ACS). - 1523-7060 .- 1523-7052. ; 13:21, s. 5838-5841
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Tidskriftsartikel (refereegranskat)abstract
- A stereoselective palladium-catalyzed oxidative carbocyclization/arylation of enallenes is described. The reaction shows wide tolerance toward highly functionalized arylboronic acids and results In a cis addition of two carbon moieties to an olefin in good to excellent yields.
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| 8. |
- Jiang, Tuo, et al.
(författare)
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Palladium-Catalyzed Oxidative Synthesis of a-Acetoxylated Enones from Alkynes
- 2016
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 55:19, s. 5824-5828
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Tidskriftsartikel (refereegranskat)abstract
- We report a palladium-catalyzed oxidative functionalization of alkynes to generate -acetoxylated enones in one step. A range of functional groups are well-tolerated in this reaction. Mechanistic studies, including the use of O-18-labeled DMSO, revealed that the ketone oxygen atom in the product originates from DMSO.
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| 9. |
- Jiang, Tuo, et al.
(författare)
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Palladium(II)/Bronsted Acid-Catalyzed Enantioselective Oxidative Carbocyclization-Borylation of Enallenes
- 2015
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Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 54:20, s. 6024-6027
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Tidskriftsartikel (refereegranskat)abstract
- An enantioselective oxidative carbocyclization-borylation of enallenes that is catalyzed by palladium(II) and a Bronsted acid was developed. Biphenol-type chiral phosphoric acids were superior co-catalysts for inducing the enantioselective cyclization. A number of chiral borylated carbocycles were synthesized in high enantiomeric excess.
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| 10. |
- Jiang, Tuo, 1986-
(författare)
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Palladium(II)-Catalyzed Oxidative Carbocyclization : Stereoselective Formation of C–C and C–B Bonds
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transition metal catalysis has emerged as one of the most versatile methods for the selective formation of carbon–carbon and carbon–heteroatom bonds. In particular, oxidative carbon–carbon bond forming reactions have been widely studied due to their atom economic feature. This thesis has been focused on the development of new palladium(II)-catalyzed carbocyclization reactions under oxidative conditions.The first part of the thesis describes the palladium(II)-catalyzed oxidative carbocyclization-borylation and -arylation of enallenes. In these reactions, the (σ-alkyl)palladium(II) intermediate, which was shown previously to undergo β-hydride elimination, could be trapped in situ by organoboron reagents (B2pin2 and arylboronic acids) to form new carbon–boron and carbon–carbon bonds. Through these two protocols, a range of borylated and arylated carbocycles were obtained as single diastereomers in high yields.The second part deals with a palladium(II)-catalyzed oxidative diarylative carbocyclization of enynes. The reaction was proposed to start with a syn-arylpalladation of an alkyne, followed by insertion of the coordinated alkene. Subsequent arylation afforded a series of valuable diarylated tetrahydrofuran and tetrahydropyran products.The final part of the thesis advances the previously developed palladium(II)-catalyzed oxidative carbocyclization-borylation of enallenes in an enantioselective manner. C2-symmetric chiral phosphoric acids were used as the novel co-catalyst to trigger the enantioselective formation of intramolecular carbon–carbon bonds. By using this chiral anion strategy, a number of enallenes were converted to the borylated carbocycles with high to excellent enantioselectivity.
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