Refernces
10.1021/ol702455v
The research focuses on the gold-catalyzed intramolecular carbocyclization of alkynyl ketones, leading to the formation of highly substituted cyclic enones. The study explores the use of coinage metal salts, particularly AuCl3 and AgSbF6, as π-electrophilic Lewis acids to activate alkynes for nucleophilic attack, facilitating the formation of new C-C and C-heteroatom bonds. The experiments involved the optimization of reaction conditions for the transformation of internal alkynyl ketones into tetrasubstituted cyclic enones, with a series of cationic coinage metal catalysts tested in toluene at 100°C. The reactants included internal alkynyl ketones with various substituents, and the analyses used to determine the yields and structures of the products were 1H NMR spectroscopy and isolated yields of products 2. The study also proposed a plausible mechanism for the gold-catalyzed carbocyclization process.
10.1021/acs.organomet.9b00378
The research focuses on the synthesis and application of fluorene complexes of Group 9 metals, specifically cobalt, rhodium, and iridium, in the context of reductive amination reactions. The study involves the preparation of η6-fluorene cyclopentadienyl complexes (η5-C5R5)M(η6-fluorene)2 (where M = Co, Rh, Ir; R = H, Me) and indenyl derivatives (η5-indenyl)M(η6-fluorene)2 through iodide abstraction using AgSbF6 in the presence of fluorene. The reactivity of these complexes, particularly the rhodium complex 2a2, was investigated, showing a higher lability of the fluorene ligand compared to benzene ligands in similar complexes. The research also explores the mechanism of fluorene elimination through a series of haptotropic rearrangements, supported by DFT calculations. The main experiments involve the synthesis of these complexes, their structural determination by X-ray diffraction, NMR spectroscopy, and the evaluation of their catalytic activity in reductive amination reactions using carbon monoxide as a reducing agent in water as a solvent. The analyses used include 1H and 13C NMR spectroscopy for structural characterization, X-ray diffraction for structural determination, and DFT calculations to understand the bonding interactions and mechanisms involved in the ligand rearrangements and catalytic activity.
10.1002/chem.202101824
The research focuses on the synthesis of indole-fused benzannulated medium-sized rings, which are structural motifs found in many bioactive compounds and thus are of significant interest in drug discovery. The study aims to address the challenge of forming medium-sized rings through the use of α-imino gold(I)-carbenes as key intermediates in a gold(I)-catalyzed cascade cyclization of azido-alkynes. The researchers successfully demonstrated that by using arenes as internal nucleophiles, they could trap the intermediary α-imino gold(I)-carbenes, leading to the formation of indole-fused benzannulated eight- and nine-membered rings. The efficiency of the process was found to be significantly affected by factors such as dilution conditions, polarization of the gold(I)-carbene, the arene moiety, and the N-protecting group. Notably, the semihollow-shaped C-dtbm ligand was found to be indispensable for the cyclization to more challenging nine-membered rings. The chemicals used in the process include phenylene-tethered azido-alkynes, gold(I) catalysts, and various ligands, such as Ph3PAuCl, tBu3PAuCl, and C-dtbm ligand, along with silver salts like AgSbF6. The developed method allows access to biologically relevant chemical space and has the potential for medicinal applications.
10.1016/j.tet.2014.03.072
The research focuses on the development of an iron-based catalytic system for the synthesis of primary, secondary, and tertiary amides through the Ritter reaction, as well as the addition of benzyl alcohols across phenylacetylene to produce substituted phenyl ketones. The purpose of this study was to improve and expand the substrate scope of the Ritter reaction, which is an atom-economical approach to amide synthesis, and to do so under mild reaction conditions that tolerate air and moisture. The conclusions drawn from the research indicate that the simple iron-catalyzed method is effective for accessing a range of amides and phenyl ketones, significantly outperforming previous methods in terms of yield. Key chemicals used in the process include iron(III) chloride (FeCl3), silver hexafluoroantimonate (AgSbF6), and acetonitrile, along with various alcohols and alkynes as substrates.
10.1039/d1cc02283k
The study investigates a method for the allylic C–H amidation of various alkenes using an Rh(III) catalyst and in situ generated iminoiodinanes. The key chemicals involved include [Cp*RhCl2]2, which acts as the catalyst; AgSbF6, used as a co-catalyst to generate the active cationic Rh(III) complex; PhI(OAc)2, serving as the hypervalent iodine oxidant for in situ generation of iminoiodinanes; and Na2HPO4·2H2O, functioning as a base. The substrates tested are a range of terminal and internal alkenes, such as allylbenzene and various substituted alkenes, along with sulfonamides like p-nitrobenzenesulfonamide, which act as the amidation source. The study demonstrates that this protocol is compatible with differently functionalized unactivated alkenes and achieves high yields with up to 99% branched selectivity. The proposed mechanism involves the formation of p-allyl and metal–nitrene intermediates, supported by mechanistic investigations. This method provides an efficient and environmentally benign approach to C–N bond formation in organic synthesis.
10.1016/j.tet.2011.07.064
The research investigates the regioselective iodination of chlorinated aromatic compounds using various silver salts as iodination reagents, aiming to develop efficient methods for synthesizing valuable iodoarene intermediates. The study explores the iodination of phenols, anisoles, anilines, chlorobenzenes, and chlorotoluenes with different silver salts (Ag2SO4, AgSbF6, AgBF4, and AgPF6) combined with I2. The results show that the choice of silver salt significantly affects the regioselectivity and yield of the iodination products. For instance, AgSbF6/I2 and AgBF4/I2 demonstrate high reactivity and selectivity in iodinating chlorinated anilines and aromatic compounds in the para position, while Ag2SO4/I2 offers reasonable yields and selectivity for certain substrates. The study concludes that silver salt-based iodination reagents, particularly those with non-coordinating anions like SbF6?, BF4?, and PF6?, provide a convenient and regioselective approach to synthesizing specific iodoarenes, which are important for applications in pharmaceuticals and environmental chemistry.
10.1039/c002660c
The research describes a platinum-catalyzed reaction involving a novel aromatization/1,3-carbonyl shift cascade of 2-epoxy-1-(methoxyalk-2-ynyl)benzenes, which is significant for its skeletal rearrangement. The study aims to explore the mechanistic significance of this reaction, which involves a remarkable 1,3-carbonyl shift to complete the aromatization and regenerate the catalyst. The chemicals used in the process include various epoxides with different substituents, such as methoxy, acetoxy, and siloxy groups, and catalysts like PtCl2/CO, PPh3AuCl/AgSbF6, and AuCl3. The research concludes that this new observation of a 1,3-carbonyl shift is helpful for the design of new catalysis, with the mechanism being elucidated through control experiments and deuterium-labelling studies.
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