Micellar Mechanisms for Desymmetrization Reactions in Aqueous Media

Water-mediated organic reactions significantly contribute to the protection of the environment. Desymmetrization reactions, which convert only one of the identical functional groups within one molecule, are cost-effective because of the low cost of the starting materials. In combination with these two merits, highly efficient and practical selective monohydrolysis reactions of symmetric diesters were previously reported. The products of these reactions are versatile building blocks. The mechanisms of this reaction are hypothesized to proceed through micellar aggregates in which the hydrophilic carboxylate anions formed by monohydrolysis are directed outward and the remaining hydrophobic groups are directed inward in governing the selectivities. Here, dynamic light scattering and electrophoretic light scattering experiments were performed for detection of the key intermediates in the reaction. These experiments revealed the existence of aggregates with negative charges on the surface in the mainly aqueous media, supporting the reaction mechanisms that control the high selectivities.

Emergence of 2-Pyrone and Its Derivatives, from Synthesis to Biological Perspective: An Overview and Current Status

Pyrone moieties are present in natural products and can be synthesized by a diverse range of synthetic methods, resulting in the formation of various derivatives through chemical modifications. Many pyrone-based derivatives are commercially available and are biocompatible. They are building blocks of various intermediates in organic synthesis. They possess remarkable biological properties including antimicrobial, antiviral, cytotoxic, and antitumor activity. These characteristics have made them valuable for the development of drugs. We have summarized recent developments in the synthesis of 2-pyrone and its derivatives and their potential applications. With regard to synthetic approaches, the focus has been on metal-free and transition metal-catalyzed reactions.

Two New Phomaligols from the Marine-Derived Fungus Aspergillus flocculosus and Their Anti-Neuroinflammatory Activity in BV-2 Microglial Cells

Two new phomaligols, deketo-phomaligol A (1) and phomaligol E (2), together with six known compounds (3-8) were isolated from the culture broth of the marine-derived fungus Aspergillus flocculosus. Compound 1 was first isolated as a phomaligol derivative possessing a five-membered ring. The structures and absolute configurations of the new phomaligols were determined by detailed analyses of mass spectrometry (MS), nuclear magnetic resonance (NMR) data, optical rotation values and electronic circular dichroism (ECD). In addition, the absolute configurations of the known compounds 3 and 4 were confirmed by chemical oxidation and comparison of optical rotation values. Isolated compounds at a concentration of 100 μM were screened for inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells. Among the compounds, 4 showed moderate anti-neuroinflammatory effects with an IC50 value of 56.6 μM by suppressing the production of pro-inflammatory mediators in activated microglial cells without cytotoxicity.