Palladium(II)-Catalyzed Synthesis of the Formylcarbazole Alkaloids Murrayaline A-C, 7-Methoxymukonal, and 7-Methoxy-O-methylmukonal

Pentachloropseudilin treatment impairs host cell invasion by Trypanosoma cruzi

Pentachloropseudilin (PClP) is a reversible and allosteric inhibitor of type 1 myosin. Here, we addressed the impact of PClP treatment of Trypanosoma cruzi and mammalian host cell on the parasite migration, cell adhesion and invasion. We observed that PClP was not toxic to either T. cruzi or host cell. Moreover, treatment of T. cruzi with PClP inhbited parasite motility, host cell adhesion and invasion. Treatment of host cell with PClP also impaired parasite invasion probably by decreasing lysosome migration to the entry site of the parasite. Therefore, PClP treatment impaired fundamental processes necessary for a successful T. cruzi infection.

Eucalyptol, an All-Purpose Product

Eucalyptus plants have attracted the attention of researchers and environmentalists worldwide because they are a rapidly growing source of wood and a source of oil used for multiple purposes. The main and the most important oil component is 1,8-cineole (eucalyptol: 60–85%). This review summarizes the literature reported to date involving the use of 1,8-cineole for the treatment of disorders. Additionally, we describe our efforts in the use of eucalyptol as a solvent for the synthesis of O,S,N-heterocycles. Solvents used in chemistry are a fundamental element of the environmental performance of processes in corporate and academic laboratories. Their influence on costs, safety and health cannot be neglected. Green solvents such as bio-based systems hold considerable additional promise to reduce the environmental impact of organic chemistry. The first section outlines the process leading to our discovery of an unprecedented solvent and its validation in the first coupling reactions. This section continues with the description of its properties and characteristics and its reuse as reported in the various studies conducted. The second section highlights the use of eucalyptol in a series of coupling reactions (i.e., Suzuki–Miyaura, Sonogashira–Hagihara, Buchwald–Hartwig, Migita–Kosugi–Stille, Hiyama and cyanation) that form O,S,N-heterocycles. We describe the optimization process applied to reach the ideal conditions. We also show that eucalyptol can be a good alternative to build heterocycles that contain oxygen, sulfur and nitrogen. These studies allowed us to demonstrate the viability and potential that bio solvents can have in synthesis laboratories.

Nitric Oxide Inhibitory Carbazole Alkaloids from the Folk Medicine Murraya tetramera C.C. Huang

The phytochemical investigation of the leaves and stems of Murraya tetramera C.C. Huang, a traditional folk medicine used as an anti-inflammatory agent, yielded 19 simple carbazole alkaloids, two of which (1-ethoxy-3-methyl-9H-carbazol-2-ol (1) and 7-hydroxy-2,8-dimethoxy-6-methyl-9H-carbazole-1-carbaldehyde (2)) are new ones. The structures of the new compounds were determined by extensive spectroscopic analysis including NMR and HR-EI-MS experiments, as well as comparison with the reported data. Most of the isolates showed potent inhibitory effects on NO production in LPS-stimulated BV-2 microglial cells with IC₅₀ values ranging from 5.1 to 15.1 μM.

Eucalyptol as a Bio-Based Solvent for Buchwald-Hartwig Reaction on O,S,N-Heterocycles

We report here the use of eucalyptol as a bio-based solvent for the Buchwald–Hartwig reaction on O,S,N-heterocycles. These heterocycles containing oxygen, sulfur and nitrogen were chosen as targets or as starting materials. Once again, eucalyptol demonstrated to be a possible sustainable alternative to common solvents.

Synthesis of Tetranuclear Palladium(II) Complexes and Their Catalytic Activity for Cross-Coupling Reactions

We have developed a short and simple synthesis of tetranuclear palladium(II) complexes that have been structurally confirmed by X-ray analysis. These complexes were formed in about 30 % overall yield by spontaneous metalation of dimethylaminoarene derivatives and exhibit a high stability. We have studied the utility of the tetranuclear palladium(II) complexes as precatalysts for Mizoroki-Heck and Suzuki-Miyaura cross-coupling reactions. Our novel complexes show excellent catalytic activities with high turnover numbers (TON) and high turnover frequencies (TOF) (e.g., for the Suzuki-Miyaura reaction: TON up to 538000 and TOF up to 23400 h^-1 at room temperature).

Anti-tuberculosis activity and structure-activity relationships of oxygenated tricyclic carbazole alkaloids and synthetic derivatives

A series of 49 oxygenated tricyclic carbazole derivatives has been tested for inhibition of the growth of Mycobacterium tuberculosis and a mammalian cell line (vero cells). From this series, twelve carbazoles showed a significant anti-TB activity. The four most active compounds were the naturally occurring carbazole alkaloids clauszoline-M (45), murrayaline-C (41), carbalexin-C (27), and the synthetic carbazole derivative 22 with MIC₉₀ values ranging from 1.5 to 3.7μM. The active compounds were virtually nontoxic for the mammalian cell line in the concentration range up to 50μM.

Applications of Palladium-Catalyzed C-N Cross-Coupling Reactions

Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

Highly electron-poor Buchwald-type ligand: application for Pd-catalysed direct arylation of thiophene derivatives and theoretical consideration of the secondary Pd0–arene interaction

Highly electron-poor SPhos ligands stabilised the Pd complex by secondary Pd⁰–arene interaction.