10.1002/chem.201701346
The study focuses on the photocatalyzed synthesis of alkylpyridines using vinylpyridines as building blocks. The researchers utilized a decatungstate salt as a photocatalyst to facilitate the addition of various hydrogen donors, such as ethers, aldehydes, alkanes, and amides, onto vinylpyridines under sunlight or flow conditions. This approach successfully yielded alkylpyridines, which are significant as they serve as building blocks for compounds with biological activity, including those with potential pharmaceutical uses and umami flavor. The process is straightforward, cost-effective, and environmentally friendly, as it minimizes the use of harmful reagents and can be conducted using natural sunlight, showcasing the potential for green and sustainable chemical synthesis.
10.1002/chem.201904241
The research focuses on the synthesis and characterization of a conformationally flexible hexakis-urea receptor (1) that exhibits allosteric behavior in recognizing anions, particularly dihydrogen phosphate. The receptor was synthesized by condensing hexakis(aminomethyl)benzene with 4-nitrophenyl-(3,5-di-tert-butylphenyl)carbamate, resulting in a compound that is unexpectedly soluble in low polarity organic solvents due to intramolecular hydrogen bonding. The receptor's ability to recognize anions such as chloride, bromide, and acetate was investigated in CDCl3, revealing a positive allosteric association in a 1:2 host-guest ratio. Uniquely, the receptor also recognized dihydrogen phosphate in a 1:3 host-guest ratio, exhibiting an amphoteric allosteric association with positive cooperativity in the initial step (K1 < K2) and negative cooperativity in the subsequent step (K2 > K3). The structures of the complexes were elucidated using single-crystal X-ray structural analysis, and association constants were determined through 1H NMR titrations and ESI FT-ICR MS, revealing the receptor's dynamic conformational changes upon guest recognition. Cyclohexane was used in the crystallization process for X-ray diffraction studies.
10.1055/s-0035-1560185
The study focuses on the reaction of N-arylpyrrolidine derivatives with 70% aqueous tert-butyl hydroperoxide (T-HYDRO) in the presence of sodium acetate trihydrate (NaOAc·3H2O) to produce tetracyclic amines via the cycloaddition of iminium ion and enamine intermediates formed in situ in cyclohexane solvent. The reaction yields tetracyclic amines in 59–78% yields, and the iminium ion intermediate can further react with potassium tert-butoxide (t-BuOK) in methanol to give cyclic amides in 85–88% yields or undergo alkylation to give nitromethyl products in 74–79% yields using t-BuOK and nitromethane in methanol. The purpose of these chemicals is to facilitate the formation of complex amine structures, which are important in organic synthesis and have potential applications in the synthesis of polycyclic amines and natural products.
10.1039/c0dt00661k
The study investigates the C–H activation of cyclic alkanes by the rhodium complexes Cp'Rh(CO)? (Cp' = η?-C?H? or η?-C?Me?) using fast time-resolved infrared spectroscopy and density functional theory (DFT) calculations. The research explores how the rate of oxidative cleavage varies among different complexes and alkanes, specifically focusing on cyclopentane, cyclohexane, and neopentane. Unlike linear alkanes, where activation occurs at primary C–H bonds with rate dependence on chain hopping, cyclic alkanes exhibit activation controlled mainly by alkane binding strength. The study highlights that steric hindrance slows down the activation of neopentane compared to cyclic alkanes. The findings contribute to understanding transition metal-mediated C–H bond activation, a crucial step for applications like alkane functionalization and catalytic transformations.
10.1016/j.chemphys.2010.04.014
The research investigates the ultrafast relaxation dynamics of a newly synthesized donor-acceptor system, 4-(ferrocen-1-yl)benzylidene-malononitrile (Fc-ph-DCV), which consists of a ferrocene (Fc) unit as an electron donor, dicyanovinyl (DCV) as an electron acceptor, and a phenyl (ph) ring as the central bridge. The study aims to understand the excited-state deactivation process of this intra-molecular charge transfer model compound. Employing femtosecond fluorescence up-conversion and transient absorption techniques, the researchers found that after photoexcitation into the higher excited S2 state, an ultrafast internal conversion into S1 occurs, with a rate significantly faster than the diffusive solvation process. The lifetime of the relaxed S1 state was found to be strongly dependent on solvent polarity, with lifetimes ranging from 40 to 50 picoseconds in acetonitrile to approximately 20 picoseconds in cyclohexane. The study concludes that the ultrafast dynamics of the charge transfer process in Fc-ph-DCV are clarified, showing that the S1 state is more stabilized in more polar solvents.
10.1021/acs.orglett.8b00797
The study presents a novel method for synthesizing ortho-alkynylated arylalkylamines using Cbz-amide as a directing group and an Ir(III) complex as the catalyst. The researchers optimized the reaction conditions, finding that [Cp*Ir(III)Cl2]2, Cs2CO3, and pivalic acid in cyclohexane at 80 °C were most effective. They demonstrated that various Cbz-protected benzylamines and arylethylamines with different substituents could be alkynylated to produce the desired products in moderate to good yields. The study also included preliminary mechanistic investigations suggesting that the amide group serves as a coordination center to assist the Ir(III) complex in C?H activation. The findings highlight the potential of this Cbz-amide-promoted C?H functionalization for practical applications in organic synthesis.
F,
Xn,
N
F:Flammable;
