10.1021/om034385g
The study investigates the reactions of 3-(pentafluorophenyl)indene and (pentafluorophenyl)cyclopentadiene with tetrakis(dimethylamido)titanium(IV), resulting in the formation of products where one or both ortho fluorines of the C6F5 group are replaced by dimethylamino groups. This suggests a titanium-mediated, intramolecular nucleophilic aromatic substitution mechanism. The research led to the isolation of organic products and the conversion of substituted cyclopentadiene to a ferrocene derivative. The study provides insights into the selective activation of polyfluorinated organic compounds, a significant challenge in synthetic chemistry, and contributes to the understanding of transition metal complex mechanisms for C-F activation.
10.1002/ejoc.200400213
The research focuses on the synthesis of a small library of highly electron-rich 2-aryl and 2-heteroaryl phenethylamines (PEAs) using the Suzuki-Miyaura cross-coupling reaction, which is enhanced by microwave irradiation for improved reaction yield and speed. The study commenced with the synthesis of benzyl [2-(2-bromo-4,5-dimethoxyphenyl)ethyl]carbamate from 2-(3,4-dimethoxyphenyl)ethylamine, followed by its coupling with various boronic acids to generate the PEAs. The reactions were optimized using sodium hydrogencarbonate as the base and tetrakis(triphenylphosphane)palladium(0) as the catalyst, with the mixture of N,N-dimethylformamide and water as the solvent. The synthesized compounds were characterized by 1H and 13C NMR spectroscopy, and low-resolution mass spectrometry (LR-MS) to confirm their structures and purities. The research also successfully extended this methodology to synthesize an apogalanthamine analogue, a complex natural product with significant biological activities, showcasing the versatility and efficacy of the developed synthetic strategy.
10.1002/adsc.200700333
The research focuses on the copper-catalyzed multicomponent reactions (MCRs) of terminal alkynes, acid chlorides, and carbodiimides to synthesize functionalized propiolamidine derivatives. The study explores the efficiency of various bases and solvents to optimize the reaction conditions. The optimal catalytic system was found to be a combination of CuI, triethylamine (TEA), and acetonitrile (CH3CN), yielding the desired products in good to excellent yields. The experiments involved a suspension of carbodiimide and acid chloride, followed by the addition of anhydrous acetonitrile, TEA, CuI, and alkyne at room temperature under a nitrogen atmosphere. The reaction mixture was stirred, then extracted with CH2Cl2, washed with saturated NaHCO3 solution and water, dried over anhydrous MgSO4, and evaporated under vacuum. The residue was purified using silica gel column chromatography with petroleum ether/ethyl acetate as the eluent. The analysis of the reaction products was based on isolated yields, which were calculated based on the amount of N,N’-dialkylcarbodiimides used.
10.1002/jhet.3454
The research focuses on the synthesis of imidazo[1,2-a]pyridines and imidazo[2,1-b]thiazoles with tertiary hydroxy substitutions, utilizing readily available substituted 2-aminopyridines, 2-aminothiazoles, and 2-aminobenzothiazoles. The experiments involved treating these amines with bromohydroxycycloalkyl ethanones under various reaction conditions to optimize yields, with sodium bicarbonate as the base in 1,4-dioxane at elevated temperatures yielding the best results. The reactants included substituted acylbromides and different amino compounds, while the analyses employed included NMR spectroscopy for structural confirmation and high-resolution mass spectrometry for molecular weight determination. The study successfully demonstrated a more efficient synthetic route for these compounds, filling gaps in existing literature on related structures.
10.1055/s-1982-29739
The research aimed to improve the procedure for the preparation of t-alkyl aryl ethers, which are compounds for which synthesis methods in the literature are scarce and complex. The main challenge in synthesizing these compounds is the occurrence of side reactions, such as elimination reactions of the starting r-alkyl halide in basic media or rearrangements of the final product to C-alkylated phenols under acid conditions. The researchers reported a convenient modification of the existing procedure using nickel bisacetylacetonate as a catalyst and sodium hydrogen carbonate as a hydrogen chloride acceptor. This method was applied to various phenols and r-alkyl chlorides to produce t-alkyl aryl ethers with yields and conversions summarized in a table. The study concluded that the procedure was not effective for phenols with strong electron-withdrawing substituents and that ortho-substituted phenols reacted sluggishly, leading to variable amounts of rearranged products. The chemicals used in the process included phenols, r-alkyl chlorides, nickel acetylacetonate, sodium hydrogen carbonate, and diethyl ether, among others.
10.1248/cpb.52.983
This research investigates the C(10)–C(19) bond cleavage reaction of 19-oxygenated androst-4-ene-3,6-dione steroids under various conditions, with the aim of understanding the effect of introducing a carbonyl group at C-6 on these reactions in relation to biological aromatization. The study explores the reactions of 19-oxygenated 6-oxo steroids 5 and 6 under both basic and acidic conditions, using chemicals such as KOH, NaHCO3, CH3COSK, HCl, and pyridine. The conclusions drawn from the research indicate that the introduction of the C6 carbonyl group into 19-hydroxy and 19-oxo steroids accelerates and/or triggers C(10)–C(19) bond cleavage reactions under both acidic and basic conditions, leading to unique outcomes for 6-oxosteroids 5 and 6.
10.1016/S0040-4039(00)80631-0
The research aims to develop a mild and efficient method for the formation of cyclic ether acetals using 2-benzenesulphonyl derivatives. The study explores the reaction of various alcohols, including those with chemically sensitive groups and sterically hindered substrates, with 2-benzenesulphonyl cyclic ethers in the presence of magnesium bromide etherate and sodium bicarbonate. This approach is particularly significant as it provides a mild alternative to traditional acidic methods for introducing protecting groups like tetrahydropyranyl. The researchers found that a wide range of alcohols reacted well under these conditions, yielding high-quality acetals without affecting other functional groups such as furan rings, silyl-protected alcohols, double and triple bonds, acetals, and carbonyl groups. The study also briefly investigated the extension of this method to glycoside bond formation, demonstrating its potential for natural product synthesis and applications involving sensitive functional groups. Key chemicals used in the research include 2-benzenesulphonyl cyclic ethers, alcohols, magnesium bromide etherate, sodium bicarbonate, and tetrahydrofuran as the solvent. The findings suggest that this mild acetalation procedure could be a valuable tool in organic synthesis, especially in contexts where functional group compatibility is crucial.
