Allobetulin

Allobetulin was synthesized at room temperature, starting from betulin by Wagner–Meerwein rearrangement in the presence of tetrafluoroboric acid diethyl ether complex. The structure of the compound obtained was confirmed by spectroscopic methods (1H, 13C NMR and IR)

Allobetulin

Allobetulin was synthesized at room temperature, starting from betulin by Wagner–Meerwein rearrangement in the presence of tetrafluoroboric acid diethyl ether complex. The structure of the compound obtained was confirmed by spectroscopic methods (1H, 13C NMR and IR)

Heterogeneous catalysts for olefin metathesis

Over the past 30 years, many strategies have been developed to immobilize well-defined metathesis catalysts on solid supports. The use of heterogeneous catalysis resulted in increased purity of the product and the possibility of recycling the catalyst. This review presents the short history of heterogeneous catalysts used in numerous types of olefin metathesis with particular emphasis on examples from recent years. The main focus was put on immobilized ruthenium alkylidene complexes based on ionic liquids, as a new promising approach, which includes noncovalent immobilization that gained interest recently. Methods of attaching catalysts and types of carriers are also presented. Homogeneous catalysts are discussed in order to emphasize the influence and potential of immobilization on the activity and selectivity of heterogeneous catalysts in olefin metathesis

Selected Plants as Sources of Natural and Active Ingredients for Cosmetics of the Future

A clear trend of replacing synthetic cosmetic ingredients with natural ones can be observed in modern cosmetology. This entails the need to search for bioactive ingredients in the natural environment, especially in plants. This paper presents a comprehensive overview of dermatological, cosmetic, and pharmacological properties of highly potent plants, namely Acmella oleracea (A. oleracea), Centella asiatica (C. asiatica), Psoralea corylifolia (P. corylifolia), Plantago lanceolata L. (P. lanceolata L.), and Solidago virgaurea L. (S. virgaurea L.). Biological activity and phytochemical constituents are presented for all plants, but special attention is paid to ingredients of particular value to the cosmetics industry. The advantages of spilanthol and bakuchiol as a replacement for the popular botulinum toxin and retinol are discussed. Natural habitats, ethnomedical importance, cultivation area, as well as extraction methods of active plant ingredients are presented in detail. A wide spectrum of biological activity indicates the enormous potential of the presented plants in formulating new cosmetic and dermatological preparations

1-Aminoalkylphosphonium Derivatives: Smart Synthetic Equivalents of <i>N</i>-Acyliminium-Type Cations, and Maybe Something More: A Review

N-acyliminium-type cations are examples of highly reactive intermediates that are willingly used in organic synthesis in intra- or intermolecular α-amidoalkylation reactions. They are usually generated in situ from their corresponding precursors in the presence of acidic catalysts (Brønsted or Lewis acids). In this context, 1-aminoalkyltriarylphosphonium derivatives deserve particular attention. The positively charged phosphonium moiety located in the immediate vicinity of the N-acyl group significantly facilitates Cα-P+ bond breaking, even without the use of catalyst. Moreover, minor structural modifications of 1-aminoalkyltriarylphosphonium derivatives make it possible to modulate their reactivity in a simple way. Therefore, these types of compounds can be considered as smart synthetic equivalents of N-acyliminium-type cations. This review intends to familiarize a wide audience with the unique properties of 1-aminoalkyltriarylphosphonium derivatives and encourage their wider use in organic synthesis. Hence, the most important methods for the preparation of 1-aminoalkyltriarylphosphonium salts, as well as the area of their potential synthetic utilization, are demonstrated. In particular, the structure–reactivity correlations for the phosphonium salts are discussed. It was shown that 1-aminoalkyltriarylphosphonium salts are not only an interesting alternative to other α-amidoalkylating agents but also can be used in such important transformations as the Wittig reaction or heterocyclizations. Finally, the prospects and limitations of their further applications in synthesis and medicinal chemistry were considered

N-Hydroxyphthalimide on a Polystyrene Support Coated with Co(II)-Containing Ionic Liquid as a New Catalytic System for Solvent-Free Ethylbenzene Oxidation

The oxidation of ethylbenzene using dioxygen was carried out applying a new catalytic system&mdash;heterogeneous N-hydroxyphthalimide (PS-NHPI) coated with an ionic liquid containing CoCl2. The catalytic system represents a combination of solid catalyst with ionic liquid layer (SCILL) and supported ionic liquid phase (SILP) techniques, wherein the resulting system utilizes CoCl2 dissolved in the 1-ethyl-3-methylimidazolium octyl sulphate ([emim)][OcOSO3]) ionic liquid phase that is layered onto the solid catalyst support. PS-NHPI was obtained by immobilizing N-hydroxyphthalimide on chloromethyl polystyrene resins by ester bonds. It was observed that novel SCILL/SILP systems significantly improved the selectivity toward acetophenone. We also demonstrate that these systems can be separated from the reaction mixture and recycled without appreciably reducing its activity and selectivity

Glycoconjugation of Betulin Derivatives Using Copper-Catalyzed 1,3-Dipolar Azido-Alkyne Cycloaddition Reaction and a Preliminary Assay of Cytotoxicity of the Obtained Compounds

Pentacyclic lupane-type triterpenoids, such as betulin and its synthetic derivatives, display a broad spectrum of biological activity. However, one of the major drawbacks of these compounds as potential therapeutic agents is their high hydrophobicity and low bioavailability. On the other hand, the presence of easily transformable functional groups in the parent structure makes betulin have a high synthetic potential and the ability to form different derivatives. In this context, research on the synthesis of new betulin derivatives as conjugates of naturally occurring triterpenoid with a monosaccharide via a linker containing a heteroaromatic 1,2,3-triazole ring was presented. It has been shown that copper-catalyzed 1,3-dipolar azide-alkyne cycloaddition reaction (CuAAC) provides an easy and effective way to synthesize new molecular hybrids based on natural products. The chemical structures of the obtained betulin glycoconjugates were confirmed by spectroscopic analysis. Cytotoxicity of the obtained compounds was evaluated on a human breast adenocarcinoma cell line (MCF-7) and colorectal carcinoma cell line (HCT 116). The obtained results show that despite the fact that the obtained betulin glycoconjugates do not show interesting antitumor activity, the idea of adding a sugar unit to the betulin backbone may, after some modifications, turn out to be correct and allow for the targeted transport of betulin glycoconjugates into the tumor cells