10.1021/om801009p
The research discusses the mechanism of the reaction of alkynes with "constrained geometry" zirconaaziridines, focusing on the synthesis and characterization of these complexes and their reactions with unsaturated electrophiles. The researchers found that PMe3 dissociation from the cg zirconaaziridine 4a was faster than from the Cp2 zirconaaziridine 5a, challenging the notion that cg complexes are better Lewis acids than their Cp2 counterparts. Key chemicals used in the study include Me4C5SiMe2N(tBu)Zr-(η2)-N(Ph)CH(Ph) (R = Me, Ph), diphenylacetylene, and (Me3Si)NCN(SiMe3), among others. The conclusions suggest that the cg zirconaaziridines are more reactive and have different dissociation rates compared to their Cp2 counterparts, providing insights into the factors influencing the reactivity of these complexes.
10.1021/ja00345a039
The research investigates the formation of η5-cyclopentadienyl(triphenylphosphine)cobaltacyclopentadienes (4) through the reaction of acetylenes with η5-cyclopentadienyl(triphenylphosphine)(acetylene)cobalt (1). The study delves into the detailed mechanism of this transformation, highlighting the intermediacy of η5-cyclopentadienylbis(acetylene)cobalt (2), which cyclizes to form coordinatively unsaturated η5-cyclopentadienylcobaltacyclopentadiene (3) via a spontaneous oxidative coupling reaction. The regioselectivity of the cyclization process is found to be primarily controlled by the steric factor of substituents rather than their electronic factor. The structures and bonding of intermediates 2 and 3 are analyzed using ab initio molecular orbital calculations. Key chemicals involved in the research include η5-cyclopentadienyl(triphenylphosphine)(acetylene)cobalt (1), various acetylenes such as diphenylacetylene, and triphenylphosphine, which play crucial roles in the formation of the cobalt metallacycles and the subsequent reactions leading to the formation of cobaltacyclopentadiene complexes (4).
10.1039/C9OB00587K
The research investigates a gold(I)-catalysed method for the intermolecular hydroamination of internal alkynes to synthesize functionalized vinylazoles under solvent-free conditions. The purpose is to develop an efficient and selective route to produce N-functionalized azoles, which are important scaffolds in pharmaceuticals and bioactive compounds. The study uses gold(I) catalysts such as [Au(IPr)(OH)], [Au(IPr)][NTf2], and [{Au(IPr)}2(μ-OH)][BF4], along with internal alkynes like diphenylacetylene and various azole nucleophiles including benzotriazole and triazoles. The reactions were optimized using additives like NBu4OTf and performed under thermal or microwave heating. The results showed high regio-, chemo-, and stereoselectivity, yielding (Z)-enamines with good to high yields. The subsequent hydrogenation of these enamines led to the formation of saturated azoles in good yields. The study concludes that this gold(I)-catalysed method offers a practical, scalable, and atom-economical alternative for synthesizing a wide range of functionalized azoles.
10.1021/ja01628a047
The research encompasses several studies focused on chemical reactions and synthesis. One study investigates the reactions of triphenylsilyllithium with stilbene and tolan, aiming to understand the products and mechanisms involved. Key chemicals include triphenylsilyllithium, stilbene, tolan, and ethylene glycol dimethyl ether. The study concludes that the reactions yield a variety of products, such as 1,2-bis-(triphenylsilyl)-1,2-diphenylethane and 1-triphenylsilyl-1,2,3,4-tetraphenylbutane, with the formation of these compounds influenced by reaction conditions and solvents. Another study prepares o-nitrophenylphosphonic acid from a mixture of nitrophenylphosphonic acid isomers using magnesium salts, highlighting the role of ortho substituents in inhibiting the formation of insoluble magnesium salts. This method allows for the isolation of pure o-nitrophenylphosphonic acid, which has been challenging to obtain through other means.
10.1016/S0022-328X(00)00748-8
The research focuses on the synthesis and diastereoselective benzannulation of glucal-derived carbene complexes involving organotransition-metal-modified sugars. The study utilizes stannylated precursors 5 and 6 to prepare triisopropylsilyl and isopropylidene-protected 1-lithio-D-glucals, which react with hexacarbonyl chromium and subsequent methylation to yield D-arabino-hex-1-enopyranosylcarbene complexes 7 and 8. These complexes then undergo diastereoselective benzannulation with tolan and 3-hexyne to produce polyoxygenated chromans 9 to 12. The research emphasizes the role of protective groups in controlling the conformation of the glucal moiety in both the carbene ligand and the chroman skeleton. The study employs 1H-NMR studies and single crystal X-ray analyses to determine the conformations of the sugar moiety in solution and solid state, indicating a 5H4-conformation for triisopropylsilyl compounds and a 4H5-conformation for isopropylidene derivatives. The reactions and analyses involve various reagents, protective groups, and spectroscopic techniques, with a particular focus on the stereochemistry and conformational control in the synthesis of these complex organic molecules.
10.1016/S0022-328X(01)01177-9
The study primarily investigates the reactions of Collman's reagent, [NEt4][CH3COFe(CO)4], with methyl iodide (CH3I) and diphenylacetylene in aprotic solvents, focusing on the synthesis of mono- and dinuclear alkenyl ketone iron complexes. The chemicals used include Collman's reagent as the starting iron complex, methyl iodide to generate reactive 'Fe(CO)4' species, and diphenylacetylene as the alkyne component. These reactants serve to explore the formation of new iron-alkenyl complexes, which are assumed to be key intermediates in various organic syntheses involving acetylenic compounds and transition-metal complexes. The purpose of these reactions is to understand the intermediate iron species involved and to synthesize new organometallic compounds with potential applications in catalysis and organic synthesis.
