10.1016/j.tetlet.2012.07.093
The study describes a new and efficient method for synthesizing indolo[3,2,1-jk]carbazoles through palladium-catalyzed intramolecular cyclization of N-(2-bromoaryl)carbazoles. The reaction involves forming carbon-carbon bonds via intramolecular arylation, which proceeds with the cleavage of C–X and C–H bonds on the carbazole ring. Various substituted N-aryl carbazole substrates, containing both electron-donating and electron-withdrawing groups, were explored under optimized conditions. The study successfully yielded indolo[3,2,1-jk]carbazoles with high thermostability, good fluorescence properties, and electron-donor potential, making them promising candidates for applications in organic electronics and material chemistry.
10.1016/j.tetlet.2014.02.046
The study presents an innovative method for the 1,4-addition of arylboronic acids to α,β-unsaturated substrates using nickel(I) complexes as catalysts. The nickel(I) species were generated in situ from Ni(PPh3)2Cl2 with the aid of activated iron, and the catalytic system was combined with NN'-bis(4-fluorobenzylidene) ethane-1,2-diamine (BFBED). The reaction is completed without the need for a base, but the presence of potassium iodide is essential. The study suggests a possible Ni(I)–Ni(III) catalytic cycle mechanism and demonstrates the efficiency of the method with yields up to 76%. The scope of the reaction was explored with various substrates and arylboronic acids, showing no significant influence from electron-withdrawing or electron-donating groups. The work provides a valuable contribution to the field of cross-coupling reactions, offering a more environmentally benign and cost-effective alternative to traditional noble metal catalysts.
10.1021/acs.orglett.5b00276
The research focuses on the development of a selective hydrogenation method for synthesizing piperidin-3-ones, which are important intermediates in the production of pharmaceutical agents and natural products. The study utilizes a homogeneous iridium catalyst to hydrogenate 3-hydroxypyridinium salts, yielding 2- and 4-substituted piperidin-3-one derivatives with high yields and chemoselectivity. The experiments involved screening various catalysts, solvents, and bases to optimize reaction conditions. Key reactants included 2-phenylpyridin-3-ol as a model substrate and [Ir(COD)Cl]2 as the catalyst, with triphenylphosphine (PPh3) as the optimal ligand and sodium bicarbonate as the base. The reaction was conducted in dichloroethane (DCE) solvent under 600 psi of hydrogen pressure at 50°C for 20 hours. The analyses used to evaluate the reaction included 1H NMR to determine conversion rates and product ratios, as well as isolated yields to assess the efficiency of the process. The optimized conditions led to full conversion and high selectivity for the desired piperidin-3-one products, with further scalability demonstrated through gram-scale experiments.
10.1039/c6gc03285k
The research focuses on the development of a novel method for the formation of S–P(O) bonds, which are crucial in the synthesis of biologically active molecules such as pesticides, insecticides, enzyme inhibitors, and pharmaceuticals. The team, led by Sungwoo Hong, successfully created a metal-, oxidant-, and halogen-free approach to directly couple R2P(O)H with sulfinic acids, overcoming the limitations of traditional methods that often involve the use of toxic and moisture-sensitive reagents, poor functional group tolerance, or harsh reaction conditions. The new method demonstrates broad substrate compatibility, including halogens and heterocyclic moieties, and is highlighted by the expeditious synthesis of optically active P-chiral phosphorothioates through stereospecific coupling. Key chemicals used in the process include various sulfinic acids, H-phosphoryl compounds, and triphenylphosphine (Ph3P) as a reductant. The study concludes that this environmentally benign protocol offers a simple and efficient alternative for S–P(O) bond formation with potential applications in chemical biology.
10.1016/S0040-4039(00)86875-6
The research aimed to prepare the parent phosphole compound 1, which was previously unknown. The study involved the protonation of phospholyl anions, which yielded unstable 1-x-phospholes that spontaneously rearranged through 1,5-proton shifts to form 2-H-phospholes. These intermediates then underwent spontaneous Diels-Alder dimerization, leading to the formation of P-P bonded [4+2] dimers. The researchers used various chemicals in their experiments, including potassium, triphenylphosphine, tetrahydrofuran (THF), and acetic acid. The process resulted in the unexpected formation of dimers, and the study proposed a mechanism for the formation of these dimers, involving the initial protonation of the phosphorus in the phospholyl anion to form a phosphole-1-H, which then rearranged to a 2-H-phosphole that dimerized through a Diels-Alder reaction. The study also explored the influence of phenyl substitution on the behavior of phospholyl anions and found that the substitution significantly affected the reaction outcomes.
10.1021/ja00086a074
The study investigates a novel "umpolung" in C-C bond formation catalyzed by triphenylphosphine. The Michael addition reaction, where a nucleophile adds to an α,β-unsaturated carbonyl compound, is a fundamental synthetic reaction in organic chemistry. Typically, the γ-carbon in such compounds acts as a nucleophile due to conjugation with an electron-withdrawing group. However, this study demonstrates that triphenylphosphine can induce the γ-carbon to act as an electrophile, facilitating nucleophilic addition. The researchers used a mixture of methyl 2-butynoate and dimethyl malonate, with triphenylphosphine as a catalyst, acetic acid, and sodium acetate in toluene. They observed the formation of a 1:1 adduct, with yields varying based on the concentration of triphenylphosphine. The study explores the range of pronucleophiles that can participate in this reaction, finding that compounds with pKa < 16 work well, while introducing alkyl groups on the acidic carbon of the pronucleophile reduces yield. The study also examines the effects of different substituents on the acetylenic acceptor, such as esters, amides, and ketones, and proposes a mechanism where triphenylphosphine acts as a nucleophilic trigger, enabling unprecedented regioselectivity and atom economy in the addition process.
10.1016/S0040-4039(00)85262-4
The study presents a novel and selective method for the deoxygenation of phenols through the reduction of aryl triflates. The key chemicals involved are aryl triflates, which are the substrates to be reduced; triethylammonium formate, which acts as the hydrogen donor; and a homogeneous palladium catalyst, typically palladium acetate, which facilitates the reaction. Triethylamine is also used as a base, and phosphine ligands, such as triphenylphosphine or 1,1'-bis(diphenylphosphino)ferrocene (DPPF), are employed to stabilize the palladium catalyst and enhance its activity. The reaction is carried out in DMF solvent, with formic acid added to generate the active hydrogen donor species. The study demonstrates that this method is highly chemoselective, tolerating various functional groups like nitro, ketones, esters, and olefins, and it provides high yields of aromatic hydrocarbons. The mechanism likely involves oxidative addition of the aryl triflate to the palladium catalyst, displacement of the triflate by formate ion, loss of carbon dioxide to form an arylpalladium(II) hydride, and subsequent reductive elimination to yield the aromatic hydrocarbon and regenerate the active palladium species.
10.1055/s-2000-8212
The research investigates the addition of zwitterionic intermediates, generated by triphenylphosphane and dimethyl acetylenedicarboxylate (DMAD), to 1,2- and 1,4-benzoquinones to synthesize novel unsaturated ?-spirolactones. The purpose is to explore the reactivity of quinones towards these intermediates and develop a method for creating highly functionalized spirolactones. The study finds that both ortho- and para-quinones readily react with the zwitterionic intermediate, yielding spirolactones in moderate to high yields. Key chemicals used include triphenylphosphane, DMAD, various benzoquinones (such as 4,6-di-tert-butyl-3-methoxy-1,2-benzoquinone and 1,4-benzoquinone), and solvents like benzene. The results show that this method provides a facile route to produce spirolactones, which are present in several biologically active natural products.
10.1016/j.tet.2007.02.082
The study focuses on the synthesis, stereochemical analysis, and functional transformations of 2-phenylselanyl-1,3-dienes. The researchers prepared these dienes using Wittig or Wittig-Horner-Emmons reactions, starting from α-phenylselanyl α,β-unsaturated aldehydes. They determined the ratio and configuration of the diene isomers using 77Se and 1H NMR spectroscopy. The dienes were then oxidized to selenoxides, which underwent [2,3]-sigmatropic rearrangements in THF, leading to the formation of allenyl alcohols, allenyl carbamates, and 1-haloalkyl allenes. This work explores the potential of selenoxides, selenimides, and dihalo-selenuranes in organic synthesis, providing a mild and selective method for preparing various functionalized allenes. The study also discusses the implications of these findings in the context of organic synthesis, including the potential use of these compounds in Diels-Alder cycloaddition reactions and as precursors for other synthetic transformations.
10.1016/S0022-328X(99)00347-2
The study focuses on the synthesis and characterization of square planar cationic rhodium(I) dicarbonyl complexes with bidentate imidazolyl ligands. The complexes {[Rh((mim)2CO)(CO)2]+BPh4 } (1), {[Rh((mim)2CH2)(CO)2]+BPh4 } (2), and {[Rh((mBnzim)2CH2)(CO)2]+BPh4 } (3) [mim=N-methylimidazol-2-yl, mBnzim=N-methylbenzimidazol-2-yl] were prepared and their structures confirmed as square planar using X-ray crystallography. The carbonyl ligands in complexes 2 and 3 were shown to be labile and could be readily exchanged for triphenylphosphine to form {[Rh((mim)2CH2)(PPh3)2]+BPh4 } (7) and {[Rh((mBnzim)2CH2)(PPh3)2]+BPh4 } (8). The complexes were fully characterized by high-field NMR spectroscopy, and the study also explored the ligand exchange reactions and the structural implications of these exchanges.
10.1016/S0040-4020(01)00528-2
The study presented in the file involves the synthesis of various compounds through a combination of chemical reactions, such as coupling and cyclization processes, using palladium-catalyzed cross-coupling reactions. Key elements of the study include investigating reaction conditions, optimizing yield, and assessing product purity. The main reactions explored are the coupling of aryl halides with olefins, with different catalysts and solvents. Various aryl halides, olefins, and coupling agents were evaluated to determine their effectiveness in producing specific products, focusing on the yield, reaction time, and stereoselectivity of the final products. The study aims to develop efficient synthetic pathways for producing complex organic molecules.
10.1271/bbb.100361
This research details the short-step syntheses of two bioactive natural compounds, (2RS,8R,10R)-YM-193221 and tyroscherin, which were isolated from Pseudallescheria sp. The purpose of the study was to further investigate their bioactivity and structure-activity relationships. The synthesis of (2RS,8R,10R)-YM-193221 was accomplished in six steps from L-tyrosine, with the relative stereochemistry determined to be 8R,10R. Tyroscherin was synthesized in eight steps, yielding an improved method over previous syntheses. Key chemicals used in the process include L-tyrosine, 3-hydroxypropyltriphenylphosphonium bromide, iodine, triphenylphosphine, imidazole, methanol, and various other reagents and solvents necessary for the reactions and purification steps. The study concluded with the successful total synthesis of (2RS,8R,10R)-YM-193221 and an improved synthesis of tyroscherin, setting the stage for further research into their absolute configurations and biological activities.
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