Oxidative Nucleophilic Cyclization of 2‑Alkynylanilines with Thiophenols under Metal-Free Conditions

An oxidative nucleophilic cyclization of 2-alkynylanilines with thiophenols under metal-free conditions was developed. The one-pot two-step reaction involves a PhI­(OAc)2-mediated oxidative dearomatization and a Brønsted acid promoted nucleophilic cyclization. DFT calculations were performed to understand the reaction pathway

Data_Sheet_1_Characterization of Tyrosinase Inhibitors in Dryopteris crassirhizoma Rhizome Using a Combination of High-Speed Counter-Current Chromatography, Affinity-Based Ultrafiltration, and Liquid Chromatography–Tandem Mass Spectrometry.DOCX

Dryopteris crassirhizoma rhizome (DCR) inhibits melanin production in B16F10 melanoma cells and tyrosinase activity. The melanin content and tyrosinase activity of DCR-treated zebrafish embryos were determined to evaluate the in vivo inhibitory effect of DCR on melanogenesis. Moreover, an off-line hyphenated method combining the high-speed counter-current chromatography, affinity-based ultrafiltration, and liquid chromatography–tandem mass spectrometry was used to identify and characterize the DCR compounds with tyrosinase inhibitory activity. Our results indicated that DCR significantly decreased the melanin content and tyrosinase activity in zebrafish embryos in a dose-dependent manner; moreover, 22 compounds in DCR presented tyrosinase inhibitory activity. In silico molecular docking prediction data indicated that the 22 compounds in DCR can form stable conformations in the active site pocket of tyrosinase.</p

Mechanical and Kinetic Studies of the Formation of Polyhalogenated Dibenzo-<i>p</i>-dioxins from Hydroxylated Polybrominated Diphenyl Ethers and Chlorinated Derivatives

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs),which may be generated from PBDEs, are more toxic than their matrix and have been detected in organisms. In this article, we have focused on the gas phase formation of polyhalogenated dibenzo-p-dioxins from several OH-PBDEs and their chlorinated derivatives. All of the geometries and frequencies are calculated at the MPWB1K/6-31+G(d,p) level of theory. The single point energy is obtained at the MPWB1K/6-311+G(3df,2p) level. Rate constants of each step have been calculated over a wide range of 200–2000 K using the canonical variational transition state (CVT) theory with small curvature tunneling (SCT) contribution. The rate equations are shown through Arrhenius formulas. The presence of chlorine atoms increases the reaction barrier for the formation of major products

Mechanical and Kinetic Studies of the Formation of Polyhalogenated Dibenzo-<i>p</i>-dioxins from Hydroxylated Polybrominated Diphenyl Ethers and Chlorinated Derivatives

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs),which may be generated from PBDEs, are more toxic than their matrix and have been detected in organisms. In this article, we have focused on the gas phase formation of polyhalogenated dibenzo-p-dioxins from several OH-PBDEs and their chlorinated derivatives. All of the geometries and frequencies are calculated at the MPWB1K/6-31+G(d,p) level of theory. The single point energy is obtained at the MPWB1K/6-311+G(3df,2p) level. Rate constants of each step have been calculated over a wide range of 200–2000 K using the canonical variational transition state (CVT) theory with small curvature tunneling (SCT) contribution. The rate equations are shown through Arrhenius formulas. The presence of chlorine atoms increases the reaction barrier for the formation of major products

Dearomatization-Induced Cycloaddition and Aromatization-Triggered Rearrangement: Synthesis of Vertically Expanded Five-Ring Fused Benzofurans

A dearomatization strategy has been developed for the efficient construction of vertically expanded five-ring fused benzofurans from ortho-alkynylphenols and ortho-alkynylarylaldimines. The stepwise procedure comprises a dearomatization-induced silver-catalyzed [3 + 2] cycloaddition followed by an aromatization-triggered ytterbium-catalyzed rearrangement

Efficient Synthesis of Arylated Carbazole from Cyclopentadienyliron Complexes

Arylated carbazoles are valuable intermediates in the preparation of organic functional materials. The present work addresses an improved process for the preparation of arylated carbazoles. This process involves a nucleophilic substitution between the cyclopentadienyliron complexes of chloroarenes and carbazole or hydroxyl carbazole, followed by photolysis of cyclopentadienyliron complexes of arylated carbazoles (Fc-carbazole). The described process combines two steps in good yields and is cost-effective, and thus, it is a practical route of preparation of arylated carbazoles. The purification strategy of arylated carbazoles was subjected to crystallization instead of column chromatography, which is very good for their industrial applications. The arylated carbazoles products were determined by Fourier transform infrared (FT-IR), liquid chromatography mass spectroscopy (LC-MS), and NMR

Dearomatization-Induced Cycloaddition and Aromatization-Triggered Rearrangement: Synthesis of Vertically Expanded Five-Ring Fused Benzofurans

A dearomatization strategy has been developed for the efficient construction of vertically expanded five-ring fused benzofurans from <i>ortho</i>-alkynylphenols and <i>ortho</i>-alkynylarylaldimines. The stepwise procedure comprises a dearomatization-induced silver-catalyzed [3 + 2] cycloaddition followed by an aromatization-triggered ytterbium-catalyzed rearrangement

Co-Former Selection for Coamorphous Amino Acid/Spironolactone Formulations and Exploration of the Amorphization Kinetics of Systems

Spironolactone (SPL) has low bioavailability due to its poor solubility. Preparing amino acid (AA)/SPL coamorphous systems is one of the effective ways to overcome this disadvantage. In this study, mixtures of SPL and 10 different AAs were prepared by the ball milling method. Solid-state characterization revealed that only l-phenylalanine (PHE) and l-tryptophan (TRP) could successfully form a homogeneous coamorphous system with SPL. In addition, we investigated the formation of AA/spironolactone (SPL) coamorphous systems and successfully defined two reliable parameter indicators of formation: the difference in octanol–water partition coefficient (Δ log P) Hmix) value. The results of the amorphization kinetics showed that the AAs with low lattice energy amorphized first, whereas the SPL (201) crystal plane, possessing the highest crystal face energy of 1.89 × 10–5 kcal/m2, disappeared at last in the process of ball milling. Stability experimental data showed that the TRP/SPL coamorphous system possesses better physical stability than the PHE/SPL coamorphous system, which was due to the higher hydrogen bond binding energy (−11.67 kcal/mol) of the TRP/SPL coamorphous system. Finally, powder dissolution experiments of the coamorphous systems indicated that the TRP/SPL coamorphous system exhibited a threefold improvement in dissolution rate compared to pure crystalline drug SPL

Solubility and Data Correlation of Isoniazid in Different Pure and Binary Mixed Solvent Systems from 283.15 K to 323.15 K

The solubility of isoniazid (INH) in eight pure solvents (water, methanol, ethanol, n-propanol, isopropyl alcohol, DMF, ethyl acetate, and acetonitrile) and three binary solvent mixtures of methanol–water, ethanol–water, and isopropyl alcohol–water were experimentally determined by gravimetric method at temperatures ranging from (283.15 to 323.15) K. Expectedly, the solubility displays temperature dependence, and the most remarkable change was found in water. In all three binary solvent mixtures, INH solubility bears a maximum at 0.2–0.4 mole fraction of alcohols, and the maximum solubility values were found varying with temperature. The experimental solubility data were well correlated by the modified Apelblat, van’t Hoff, CNIBS/R–K, and Apel–JA equations. Among these models, the modified Apelblat model produces the best fitting results