10.1016/S0040-4039(01)02334-6
The research focuses on the microwave-enhanced Goldberg reaction, a novel and efficient method for synthesizing N-arylpiperazinones, N-arylpiperazinediones, and N-aryl-3,4-dihydroquinolinones. The study explores the use of microwave irradiation to accelerate the Goldberg reaction, which traditionally requires harsh conditions, by employing N-methyl-2-pyrrolidinone (NMP) as a solvent. The experiments involved reacting aryl bromides with protected 2-piperazinones or 2,5-piperazinediones under various conditions, with and without microwave irradiation, to optimize reaction rates and yields. Key reactants included bromobenzene, acetanilide, and different polar solvents. The analyses used to determine the success of the reactions and the structures of the products comprised HPLC, NMR, MS, and HRMS techniques. The results demonstrated significant time and energy savings with microwave irradiation, establishing it as a powerful tool in organic synthesis for these transformations.
10.1021/op300162d
The research focuses on the optimization of the reductive debenzylation of hexabenzylhexaazaisowurtzitane (HBIW), a key step in the synthesis of high energy density material HNIW (CL-20). The study employs palladium hydroxide on activated carbon as a catalyst, characterized using techniques like nitrogen adsorption/desorption isotherm, hydrogen isotherm, SEM, and TEM. A central composite design (CCD) was utilized to optimize reaction conditions, examining the impact of four variables: catalyst to HBIW percent, reaction temperature, hydrogen pressure, and acetic anhydride (Ac2O) mole ratio on reaction yield. The optimal conditions were determined to be 20% (w/w) catalyst to HBIW, 48.5°C reaction temperature, 4.25 bar hydrogen pressure, and an Ac2O/HBIW mole ratio of 10.9, resulting in a 73% yield. The experiments involved the use of HBIW, DMF, acetic anhydride, and bromobenzene, with the synthesized product TADB characterized by melting point and TLC. The catalyst was analyzed for surface area, pore size distribution, active surface area, and palladium distribution using the aforementioned techniques.
10.1002/anie.201600379
The research aims to develop a highly enantioselective method for synthesizing chiral 1,4-benzodioxanes, 1,4-benzooxazines, and chromans, which are important structural units in many bioactive natural products and drugs. The study focuses on using palladium-catalyzed alkene aryloxyarylation reactions, with key chemicals including 2-((2-methylallyl)oxy)phenol (1a), various aryl halides such as bromobenzene (2a), and chiral monophosphorus ligands like L4 and L5. The researchers optimized the reaction conditions, finding that a strong base like NaOtBu and a solvent like hexafluorobenzene (C6F6) enhanced both yield and enantioselectivity. The method demonstrated high yields (up to 90%) and excellent enantioselectivity (up to 95% ee) for a range of substrates, including those with different aryl and heteroaryl groups. The study concludes that the chiral monophosphorus ligands L4 and L5 are crucial for the high reactivity and enantioselectivity of the transformations. The findings not only provide a practical route for synthesizing these chiral compounds but also offer valuable insights into the design of better catalytic systems for similar transformations.
10.1007/s11243-012-9635-y
The research focuses on the synthesis, characterization, and catalytic activity of three palladium(II) complexes containing Schiff base ligands. The purpose of this study was to create new Pd(II) complexes that could serve as heterogeneous catalysts in organic reactions, specifically in the Heck coupling reaction of bromobenzene with acrylic acid. The researchers synthesized three new Pd(II) complexes: [Pd4(L1)4] (1), [Pd2(L2)2Cl2] (2), and [Pd(L3)2Cl2] (3), using solvothermal methods. The Schiff base ligands, HL1, L2, and L3, were prepared by condensation reactions involving benzaldehyde or 2,4-dichlorobenzaldehyde with aromatic amines. The palladium complexes were then formed by reacting PdCl2 with these ligands under solvothermal conditions. The study concluded that these complexes show moderate catalytic activity in the Heck coupling reaction, and their effectiveness is sensitive to the choice of base and solvent. The chemicals used in the process included palladium chloride, methanol, ethanol, and various aromatic amines and aldehydes for the preparation of the Schiff base ligands, as well as bromobenzene, acrylic acid, and triethylamine for the catalytic reactions.
10.1007/s11172-008-0326-y
This research investigates the use of carborane-containing phosphorus derivatives as ligands in Pd-catalyzed cross-coupling reactions, specifically the Suzuki-Miyaura reaction, which forms carbon-carbon bonds by coupling aryl halides with boronic acids. The purpose is to develop ligands with optimized steric and electronic properties to enhance catalytic activity. The study synthesized various phosphine and phosphite ligands with different substituents and tested their efficiency in the cross-coupling reactions. Key chemicals used include phenylboronic acid, aryl halides like bromobenzene and 4-bromotoluene, and various carborane-containing ligands. The results showed that ligands with electron-withdrawing carboranyl substituents and sterically congested phosphorus centers provided the highest conversion rates. Additionally, anhydrous reaction conditions enabled the use of more synthetically accessible phosphite ligands. The findings suggest that fine-tuning the electronic and steric properties of carborane ligands can significantly improve their performance in cross-coupling reactions, opening new avenues for developing more active catalysts.
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