Vol. 22 No. 2 (2024)

Podophyllotoxin, its derivatives and structural analogues are an extensive group of aryl-tetralin-lignans of interest in pharmacology due to their promising anticancer and antitumor activity. The synthesis methods that have been proposed to date seek to resolve synthetic, stereochemical, pharmacodynamic and environmental aspects. In this review we have updated and brought together different classifications of lignan and podophyllotoxin synthesis. Transformation methods focus on the strategies used to form or functionalize rings A, B, C and D, as well as the configuration of the system of four stereogenic centers that fuse rings C and D.

The literature review discusses and systematizes synthetic approaches to medium-sized cycles and macrocycles based on ring expansion reactions of bi- or polycyclic systems via C-N bond cleavage. Ring expansion reactions of bicyclic ammonium salts proceed via thermal decomposition or the action of strong bases. Bi- or polycyclic systems containing a common amine group can be reduced with strong reducing reagents, e.g. lithium aluminum hydride. Ammonium derivatives are much more prone to nucleophilic attack and quite often are used as starting materials for the synthesis of medium-sized cycles. Bicyclic systems containing a common aminal or amidine group are used for the synthesis of medium-sized rings and macrocycles via cleavage of the endocyclic C-N bond. Various methods of their activation and reduction are discussed in the review.

The review is aimed at summarizing and systematizing information on various methods of deactivation of chemical warfare agents required on the battlefield, in laboratories, research institutions, production facilities, as well as information on storage and destruction of poisonous substances. The review provides data on warfare poisons with different tactical and physiological characteristics and outlines the main directions of their neutralization, which are the most effective under the conditions of their real use. In the first part of this review, the methods of deactivation of warfare poisonous substances using functionalized metal-organic framework materials, on which reactions of their transformation into low-toxic products take place, are considered in detail. In addition, metal-organic frameworks are porous crystalline structures that have many areas of application and can be used as adsorbents and catalysts. The above material shows the importance of general knowledge about the physical and chemical properties of chemical warfare agents, the rate of their decomposition, the advantages and disadvantages of certain available technologies for their application. This review can be useful for finding new and improving known methods of decontamination of chemical warfare agents and other ecotoxicants, for environmental protection.

Difluoromethylation of various 2-pyridones with the available industrial reagent chlorodifluoromethane (Freon-22) has been studied. Some relationships between the ratio of difluoromethylation products and the reaction conditions, as well as the presence of substituents in the pyridine ring, have been found. The possibility of obtaining difluoromethylation products at the nitrogen atom, in some cases with a preparative yield, has been investigated.