Stereoselective Hydroxycarbonylation of Vinyl Bromides to α,β-Unsaturated Carboxylic Acids in the Ionic Liquid [BMIM]PF6

New ψ-Santonin Derivatives from Crossostephium chinense and Their Anti-Proliferative Activities against Leishmania major and Human Cancer Cells A549

Previously, we reported two cytotoxic ψ-santonin-amino acid conjugates isolated from the EtOAc layer of Crossostephium chinense. However, a further phytochemical investigation seems to be required because of the few reports of similar derivatives. In this study, we targeted the 1-BuOH layer, which resulted in the isolation of seven new ψ-santonin derivatives (1-7) together with ten known compounds (8-17). The structures of 1-7 were elucidated based on spectroscopic methods, including 1D and 2D NMR experiments (1H, 13C, DEPT, COSY, HSQC, and HMBC), IR spectrum, and high-resolution electrospray ionization-mass spectrometry (HR-ESI-MS). The stereochemistry of new compounds was confirmed by NOESY and ECD calculations. All isolated compounds were evaluated by in vitro experiments for their anti-proliferative activities against Leishmania major, human lung cancer cell line A549, and Vero cells. As a result, most of the ψ-santonin derivatives, especially 1-5, showed significant cytotoxicity against L. major with a lower IC50 than the positive control we used (miltefosine).

Quantum mechanical investigation on the hydroxycarbonylation of styrene using a palladium complex catalyst

Here we have investigated the kinetics and mechanism of [Pd(pyca)(PPh3)(OTS)/PPh3/TSOH/LiCl] system-catalysed hydroxycarbonylation of styrene using density functional theory (DFT). A new mechanism is proposed in which there is an unoccupied coordination position on the Pd. In the final step, this provides the necessary conditions for an attack of the coordinated H2O on the acyl moiety, resulting in production of the final product. The proposed mechanism consists of three main steps. The final step, the formation of the products, is rate-determining. The DFT results are in good agreement with experiment.

Cs2CO3-promoted carboxylation of N-tosylhydrazones with carbon dioxide toward α-arylacrylic acids

A Cs2CO3-promoted carboxylation of N-tosylhydrazones and CO2 has been developed. The reaction proceeded efficiently at 80 °C under atmospheric CO2, gave the corresponding α-arylacrylic acids in moderate to good yields. This method was featured with (1) the employment of Cs2CO3 rather than (n)BuLi as the base; (2) a reaction temperature of 80 °C rather than -78 °C.

Palladium-catalyzed carbonylation reactions of aryl halides and related compounds

Palladium-catalyzed carbonylation reactions of aromatic halides in the presence of various nucleophiles have undergone rapid development since the pioneering work of Heck and co-workers in 1974, such that nowadays a plethora of palladium catalysts are available for different carbonylative transformations. The carboxylic acid derivatives, aldehydes, and ketones prepared in this way are important intermediates in the manufacture of dyes, pharmaceuticals, agrochemicals, and other industrial products. In this Review, the recent academic developments in this area and the first industrial processes are summarized.