10.1021/ol800115p
The research described in the article focuses on the synthesis of chiral 3,3'-bipyrroles, which are significant for their presence in natural products and potential applications in conducting polymers and pharmaceuticals. The experiments involved a Lewis acid-catalyzed one-pot, three-component route using diaroyl acetylene and 1,3-dicarbonyls as reactants, with ammonium acetate serving as the nitrogen source. The reaction was optimized using various Lewis acid catalysts, with In(OTf)3 and InCl3 proving most effective, and isopropyl alcohol (IPA) as the preferred solvent. The axial chirality of the bipyrroles was confirmed through X-ray crystal structure analysis and Density Functional Theory (DFT) calculations. The absolute configuration of the enantiomers was determined by comparing theoretical CD spectra calculations using the ZINDO method with experimental CD spectra obtained after separating the racemates on a chiral column. The research also explored the atropisomerism of bipyrroles and their potential applications, suggesting further studies for their use as chiral ligands and in electrochemical sensing.
10.1055/s-2005-872679
The research discusses a novel hydroiodination reaction of alkenes and alkynes using titanium tetraiodide (TiI4) as a reagent, which results in the formation of alkyl iodides, vinyl iodides, and alkyl diiodides with good yields. The study explores the reaction conditions and substrate scope, revealing that the presence of acetals leads to intriguing C–C bond-forming products, such as 1,3-diiodides from olefins and 1,5-diiodo-1,4-dienes from acetylenes. The experiments involve treating various olefins and alkynes with TiI4 in CH2Cl2 at room temperature, with optimization of reaction conditions to achieve the best yields. The analyses used to characterize the products include purification by silica gel TLC and spectral methods, with the yields of products reported in a table format. The research also touches upon the potential intermediates and mechanisms involved in the reaction, although these are not yet fully confirmed.
10.1055/s-0028-1088018
The study focuses on copper-catalyzed azide-alkyne 1,3-dipolar cycloadditions (CuAAC) with paramagnetic azide and alkyne building blocks, which are used to synthesize complex spin-labeled molecules such as amino acids, carbohydrates, drug molecules, and biradicals. The chemicals used in the study include various nitroxides, azides, and acetylenes, which serve as building blocks for the click reactions. These reactions are crucial for incorporating nitroxides into biological and non-biological structures for subsequent analysis using electron paramagnetic resonance (EPR). The purpose of these chemicals is to enable the site-selective introduction of nitroxide side chains into proteins and other biomolecules, allowing for the exploration of the structure, dynamics, and interactions of complex biomolecules. The study demonstrates the applicability of paramagnetic azides and acetylenes in CuAAC reactions and their potential use in modifying biomolecules with spin labels, which can be valuable for structural and dynamic studies of proteins and other macromolecules.
10.1021/ja00247a049
The study focuses on the synthesis and characterization of tetramethyltetratellurafulvalene (TMTTeF) and its electrochemical properties. TMTTeF was synthesized using a method involving acetylene, hexamethylditin, n-BuLi, and elemental tellurium, with tetrachloroethylene as a reactant in the final step. The compound was purified through chromatography and characterized by spectroscopic methods, including mass spectrometry and NMR spectroscopy. The electrochemical data, obtained by cyclic voltammetry, revealed that TTeF exhibits two reversible one-electron oxidations, with an ionization potential between that of tetrathiafulvalene (TTF) and tetraselenafulvalene (TSF). The study also discusses the presence of a six-membered ring isomer in the crude TTeF, identified through an irreversible oxidation peak in the cyclic voltammogram. The research aims to explore the potential of TTeF in forming organic metals and to make this synthesis available to the broader scientific community for further exploration of its solid-state properties.
10.1007/BF00553698
The study investigates the formation of titanium nitride (TiN) and titanium carbonitride (TiCN) films using ion beam assisted deposition (IBAD) and reactive ion beam assisted deposition (RIBAD) techniques. Titanium is evaporated and simultaneously irradiated with nitrogen ions to form TiN, while the introduction of acetylene (C2H2) leads to the formation of TiCN. The research examines how the composition, purity, hardness, adhesion, and corrosion resistance of these films are influenced by process parameters such as nitrogen ion current density and reactive gas pressure. The study finds that the hardness of TiN films can reach up to 2800 kg/mm2 and TiCN films up to 4000 kg/mm2, with adhesion values of up to 15 N for TiN and 10 N for TiCN. Both coatings significantly reduce the corrosion rate of stainless steel in seawater, demonstrating their potential as protective coatings.
10.1016/j.tet.2005.07.022
The study focuses on the carbometallation reactions of fluorine-containing internal acetylenes with various organocopper reagents derived from organolithium, Grignard, and organozinc reagents. The main objective was to investigate the regio- and stereo-selectivity of these reactions, which are crucial for the synthesis of fluoroalkylated molecules, particularly alkenes with fluoroalkyl groups that are found in biologically active compounds. The reactions proceeded smoothly, yielding vinylcopper intermediates that could then react with electrophiles to form trisubstituted alkenes in high to excellent yields. The study also successfully applied these reactions in the total synthesis of the anti-estrogen drug, panomifene, demonstrating the synthetic utility of the developed methods. Chemicals used in the study included fluoroalkylated internal alkynes, organocopper reagents, and various electrophiles for cross-coupling reactions, serving the purpose of exploring novel synthetic approaches for the preparation of fluoroalkylated molecules with potential pharmaceutical applications.
10.1021/om9509711
This study investigates the insertion of ethyne into ruthenium-silicon (Ru-Si) bonds in coordinatively unsaturated silyl complexes of ruthenium, aiming to provide insight into the catalytic cycle of alkyne hydrosilylation. The research involves the synthesis of five-coordinate silyl complexes, such as Ru(SiMe3)Cl(CO)(PPh3)2, which react with ethyne to form silylalkenyl complexes like Ru(CH=CHSiMe3)Cl(CO)(PPh3)2. Subsequent reactions lead to dicarbonyl derivatives and metallacyclic compounds. Structural analyses, including X-ray crystallography, confirmed the geometry of these products.
10.1021/jo00051a035
The study reports a formal enantioselective total synthesis of the spongian diterpene (-)-dendrillol-1 (3), isolated from marine organisms. The synthesis hinges on intramolecular acetalization of an acid-dialdehyde (4), derived from (+)-podocarp-8(14)-en-13-one (6). Key steps include photochemical reaction of 6 with acetylene to introduce a latent dialdehyde unit, reductive carboxylation at C-13 to obtain acid 18, and ozonolysis to elaborate the dialdehyde moiety. Various methods for reductive carboxylation were explored, including reductive nucleophilic acylation and reductive cyanation, with the latter yielding acid 18 in acceptable yield. The final step involves oxidative cleavage of the double bond in 18, followed by spontaneous internal lactone-hemiacetal formation to yield dendrillol-1 (3). The study also examines an alternative approach involving epoxide formation and rearrangement but finds that it leads to a beyerane compound rather than the desired aldehyde. The synthesized dendrillol-1 matches the natural product in physical and spectroscopic properties, establishing its absolute configuration.
F+
F+:Highly flammable;
