Process Development of a Suzuki Reaction Used in the Manufacture of Lanabecestat

Rapid Construction of Polycyclic Skeletons via Brønsted-Base-Catalyzed Annulations of Ethylidene 1,3-Indenediones and Vinyl 1,2-Diketones

Brønsted-base-catalyzed diversified annulations between ethylidene 1,3-indenediones and vinyl 1,2-diketones have been achieved, delivering three types of products containing oxabicyclo[3.2.1]octane, spiro[4.5]decane, and branched triquinane skeletons, respectively, which widely exist in natural products and bioactive substances. Two unprecedented reaction modes have been disclosed, and the reactions could be readily scaled up. The protocol shows the potential of 1,2-diketone-mediated reactions in the rapid construction of complicated polycyclic scaffolds.

Catalytic 2-Ethylhexanoic Acid Promotes Mild Miyaura Borylations

The Miyaura borylation of aryl and heteroaryl chlorides and bromides using a combination of potassium carbonate and 5 mol % 2-ethylhexanoic acid at 25 °C is reported. The in situ generation of a catalytic amount of potassium 2-ethylhexanoate under these conditions avoids the need for special handling of stoichiometric quantities of hygroscopic potassium 2-ethylhexanoate during the reaction setup as well as difficulties in removing the resulting carboxylic acid during product isolation.

Robust C-PdNi-CNF Sandwich-Structured Catalyst for Suzuki Reactions and Experimental Study on the Mechanism

The stability of metal nanoparticles is one of the key issues for their catalytic applications. In this study, we fabricated a sandwich structure to protect the metal nanoparticles. A carbon layer was used to wrap the PdNi nanoparticles on the carbon fiber, and the whole preparation process was simple and green. Electron transfer occurs between the carbon layer and the metal nanoparticles, making the two more closely combined. As a catalyst for the Suzuki reaction, it exhibits highly efficient catalysis and excellent stability. The calculated TOF reaches 18 662 h^-1. After nine cycles, there was almost no decrease in performance. Additionally, we found that the addition of iodobenzene into the chlorobenzene reaction system could significantly improve the chlorobenzene conversion, and we proved that the catalyst has fine activity and stability with a bright future in commercial applications. The possible catalytic mechanism of Suzuki reaction was proposed based on experimental results. This study provides a simple and green method to prepare encapsulated metal nanoparticle catalysts and gives a deep insight into Suzuki reaction.

TEMPO mediated oxidative annulation of aryl methyl ketones with amines/ammonium acetate for imidazole synthesis

A facile synthesis of 1H-imidazoles by direct oxidative annulation of aryl methyl ketones and primary amines has been developed in the presence of TEMPO under weakly acidic conditions. By replacing amines with ammonium acetate, 2H-imidazole skeletons were achieved for the first time from ketones. Substrates containing various functional groups, such as alkyl, aryl, naphthyl, halogen (F, Cl, Br, I), nitro, trifluoromethyl, sulfonyl ester, furyl, thienyl, and pyridyl groups, were readily transformed into the desired products. The application potential of this method was verified by the scale-up synthesis and Sonogashira coupling functionalization of imidazoles. Mechanistically, the α-TEMPO-enamine adduct may serve as the key reaction intermediate.

Synthesis of Novel (S)-3-(1-Aminoethyl)-8-pyrimidinyl-2-phenylisoquinolin-1(2H)-ones by Suzuki-Miyaura Coupling and Their Cell Toxicity Activities

A series of (S)-3-(1-aminoethyl)-8-pyrimidinyl-2-phenylisoquinoline-1(2H)-ones 3a-3k was synthesized in 40-98% yield through Suzuki-Miyaura coupling using Pd(PPh₃)₂Cl₂, Sphos, and K₂CO₃ in THF/H₂O mixed solvent. All newly synthesized compounds were evaluated for cell viability (IC₅₀) against MDA-MB-231, HeLa, and HepG2 cells. The antitumor activities of 3a-3k were improved when various pyrimidine motifs were introduced at position C-8 of the isoquinolinone ring.

Spirocyclic Scaffolds in Medicinal Chemistry

Spirocyclic scaffolds are incorporated in various approved drugs and drug candidates. The increasing interest in less planar bioactive compounds has given rise to the development of synthetic methodologies for the preparation of spirocyclic scaffolds. In this Perspective, we summarize the diverse synthetic routes to obtain spirocyclic systems. The impact of spirocycles on potency and selectivity, including the aspect of stereochemistry, is discussed. Furthermore, we examine the changes in physicochemical properties as well as in in vitro and in vivo ADME using selected studies that compare spirocyclic compounds to their nonspirocyclic counterparts. In conclusion, the value of spirocyclic scaffolds in medicinal chemistry is discussed.

Solubility of Phenylboronic Acid and its Cyclic Esters in Organic Solvents

The solubilities of phenylboronic acid, its pinacol ester and azaester in organic solvents (chloroform, 3-pentanone, acetone, dipropyl ether and methylcyclohexane) have been determined experimentally by a dynamic method, in which the disappearance of turbidity was determined by measuring of light intensity using a luminance probe. Phenylboronic acid has high solubility in ether and ketones, moderate in chloroform and very low in hydrocarbon. Pinacol ester and azaester show better solubility than the parent acid in all tested solvents. For pinacol ester differences between particular solvents are small, while for azaester the differences are significant. For both esters the highest solubility is observed in chloroform and the lowest in the hydrocarbon. The results have been correlated by the Wilson, NRTL and Redlich–Kister equations. For the phenylboronic acid better correlation of the data is obtained by polynomials in comparison with the above equations. It is connected with additional acid-anhydride equilibrium in the system. The influence of polarity of the solvents on the solubility is discussed.