- Rhodium-Catalyzed Aerobic Decomposition of 1,3-Diaryl-2-diazo-1,3-diketones: Mechanistic Investigation and Application to the Synthesis of Benzils
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The conversion of 1,3-diaryl-2-diazo-1,3-diketones to 1,2-daryl-1,2-diketones (benzils) is reported based on a rhodium(II)-catalyzed aerobic decomposition process. The reaction occurs at ambient temperatures and can be catalyzed by a few dirhodium carboxylates (5 mol %) under a balloon pressure of oxygen. Moreover, an oxygen atom from the O2 reagent is shown to be incorporated into the product, and this is accompanied by the extrusion of a carbonyl unit from the starting materials. Mechanistically, it is proposed that the decomposition may proceed via the interaction of a ketene intermediate resulting from a Wolff rearrangement of the carbenoid, with a rhodium peroxide or peroxy radical species generated upon the activation of molecular oxygen. The proposed mechanism has been supported by the results from a set of controlled experiments. By using this newly developed strategy, a large array of benzil derivatives as well as 9,10-phenanthrenequinone were synthesized from the corresponding diazo substrates in varying yields. On the other hand, the method did not allow the generation of benzocyclobutene-1,2-dione from 2-diazo-1,3-indandione because of the difficulty of inducing the initial rearrangement.
- Zhu, Jia-Liang,Tsai, Yi-Ting
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p. 813 - 828
(2020/12/22)
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- Method for synthesizing 1, 3-dicarbonyl compound based on terminal alkyne and acyl halide by one-pot process
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The invention belongs to the technical field of catalytic synthesis, and discloses a method for synthesizing a 1, 3-dicarbonyl compound by a one-pot process, and the method comprises the following steps: by using simple palladium and copper salts as catalysts, reacting terminal alkyne with acyl halide at 0-80 DEG C for 0.5-12 hours under the action of trifluoromethanesulfonic acid to obtain the 1,3-dicarbonyl compound, wherein the molar ratio of the terminal alkyne to the acyl halide to the palladium salt to the copper salt to the trifluoromethanesulfonic acid is 1 to (1 to 2) to (0.00001 to0.10) to (0.00001 to 0.10) to (0.00004 to 0.40); the catalysts used in the method are common the commercialized palladium salt and copper salt, reagents used in the reaction are commercialized reagents, in addition, the raw materials are cheap and easy to obtain, functional group tolerance is good, reaction conditions are mild, operation is easy and convenient, and atom economy is high.
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Paragraph 0069-0074; 0078-0080
(2020/07/21)
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- An effective preparation of both 1,3-diketones and nitriles from alkynones with oximes as hydroxide sources
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An effective phosphine-catalyzed protocol has been established for the syntheses of 1,3-diketones and nitriles from alkynones with oximes as hydroxide surrogates. This method features the use of a phosphine catalyst, compatibility with various functional groups and ambient temperature, which makes this approach very practical. A plausible mechanism was proposed.
- Chen, Pei,Zhang, Qian-Qian,Guo, Jia,Chen, Lu-Lu,Wang, Yan-Bo,Zhang, Xiao
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p. 6958 - 6966
(2018/10/02)
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- Asymmetric transfer hydrogenation of unsymmetrical benzils
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In this paper, the asymmetric transfer hydrogenation of unsymmetrical benzils with m, p-substituents was conducted with a substrate/catalyst molar ratio of 100 at 40°C for 24 h to produce (S,S)-hydrobenzoins in good yields (76.2% to 97.1%) with high diastereomeric (syn/anti = 10.8 to 29.7/1) and enantiomeric purities (86.1%ee syn to 98.9%ee syn). Unfortunately, the unsymmetrical benzils with the o-substituents such as electron-donating (R = CH3, OCH3) and electron-withdrawing groups (R = F, Cl, CF3) resulted in poor yields (0% to 31.2%), even at 40°C for 72 h. These products had inefficient diastereoselectivities (syn/anti = 1.5 to 5.0/1) caused by steric effects. Furthermore, the results of a dynamic-kinetic study were used to propose a plausible reaction pathway of unsymmetrical benzil using 3-methoxy-1,2-diphenyl ethanedione as an example.
- Zhang, Hao,Feng, Dandan,Sheng, Haibo,Ma, Xuebing,Wan, Jinwei,Tang, Qian
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p. 6417 - 6423
(2014/02/14)
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- NOVEL COMPOUNDS
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This invention relates to compounds of formula (I) their use as positive allosteric modulators of mGlu5 receptor activity, pharmaceutical compositions containing the same, and methods of using the same as agents for treatment and/or prevention of neurological and psychiatric disorders associated with glutamate dysfunction such as schizophrenia or cognitive decline such as dementia or cognitive impairment. A, B, Ar, R1, R2, R3 have meanings given in the description.
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Page/Page column 51; 53
(2013/06/27)
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- NOVEL COMPOUNDS
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This invention relates to compounds of formula I their use as positive allosteric modulators of mGlu5 receptor activity, pharmaceutical compositions containing the same, and methods of using the same as agents for treatment and/or prevention of neurological and psychiatric disorders associated with glutamate dysfunction such as schizophrenia or cognitive decline such as dementia or cognitive impairment. A, B, Ar, R1, R2, R3 have meanings given in the description.
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Paragraph 0257; 0258; 0259; 0260
(2013/06/05)
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- Synthesis of some β-diketone complexes of lanthanides and study of their shift reagent effects
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A series of complexes of ortho, meta and para substituted dibenzoylmethane(DBM) with lanthanides(Ln) have been synthesized and the induced shifts in 1H NMR spectra on n-pentanol have been studied. The studies of the shift behaviour of trivalent
- Salar Amoli,Aziz,Mohanazadeh
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p. 1004 - 1005
(2007/10/03)
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