Construction of Chiral Cyclic Compounds Enabled by Enantioselective Photocatalysis

Chiral cyclic molecules are some of the most important compounds in nature, and are widely used in the fields of drugs, materials, synthesis, etc. Enantioselective photocatalysis has become a powerful tool for organic synthesis of chiral cyclic molecules. Herein, this review summarized the research progress in the synthesis of chiral cyclic compounds by photocatalytic cycloaddition reaction in the past 5 years, and expounded the reaction conditions, characters, and corresponding proposed mechanism, hoping to guide and promote the development of this field.

Cu-Catalyzed Allylation of Amines with Cyclopropyldiphenylsulfonium Trifluoromethanesulfonate

Cyclopropyldiphenylsulfonium salt is a famous ylide precursor that was previously extensively employed in the preparation of cyclic compounds and has been successfully utilized as an efficient allylation reagent in this work. The Cu-catalyzed reactions of cyclopropyldiphenylsulfonium trifluoromethanesulfonate with amines in the presence of an appropriate ligand provided the N-allylated products in good yields. Aliphatic/aromatic amines and primary/secondary amines were all mildly converted under the reaction conditions. This protocol was also applicable to N-functionalization of drug molecules, supplying the corresponding N-allylated compounds in satisfactory yields. The reaction showed good functional group tolerance, a wide range of substrates, and excellent chemoselectivity, which offered an interesting method for the synthesis of N-allyl amines.

Covalent nanosynthesis of fluorene-based macrocycles and organic nanogrids

This paper presents an overview of synthetic approaches for fluorene-based cyclic compounds by examining four different connection models of fluorenes, involving 2,7-, 3,6-, 9,9-, and 2,9-linked patterns.

Hydroelementation of diynes

This comprehensive review highlights the hydroelementation reactions of conjugated and separated diynes to various products including enynes, dienes, allenes, polymers or cyclic compounds, and their further transformation to valuable compounds.

Post-fire composition of lipids in waters and plants of Great Vasyugan Mire

A lipid compositions were determined in water and plant samples taken in natural and burnt-out areas of the Bakchar bog (northeastern part of Great Vasyugan Mire) located in the basin of the Gavrilovka River within Tomsk region and were analyzed via gas chromatography-mass spectrometry. The following main groups of organic compounds have been identified: acyclic n-alkanes, fatty acids, and n-alkan-2-ones. Among cyclic compounds steroids, sesquiterpenoids, and pentacyclic triterpenoids have been identified. It was shown that lipids in waters contained biomolecules of plants grown in the areas under study. Chemical indicators reflecting the disappearance of plants since a fire and their restricted distribution or replacement of some plant species with others were found out. These indicators can be used in paleoclimatic reconstructions to fix post-pyrogenic layers in the sedimentary rock strata.

Quinazoline Derivatives as Potential Therapeutic Agents in Urinary Bladder Cancer Therapy

Cancer diseases remain major health problems in the world despite significant developments in diagnostic methods and medications. Many of the conventional therapies, however, have limitations due to multidrug resistance or severe side effects. Bladder cancer is a complex disorder, and can be classified according to its diverse genetic backgrounds and clinical features. A very promising direction in bladder cancer treatment is targeted therapy directed at specific molecular pathways. Derivatives of quinazolines constitute a large group of chemicals with a wide range of biological properties, and many quinazoline derivatives are approved for antitumor clinical use, e.g.,: erlotinib, gefitinib, afatinib, lapatinib, and vandetanib. The character of these depends mostly on the properties of the substituents and their presence and position on one of the cyclic compounds. Today, new quinazoline-based compounds are being designed and synthesized as potential drugs of anticancer potency against bladder cancers.

Cooperative Rh(II)/Pd(0) Dual Catalysis for the Synthesis of Carbo- and Heterocyclic Compounds

Dual transition-metal catalysis has been introduced as a robust tool to synthesize a diverse range of organic compounds which are not able to be accessed by traditional single metal catalysis. In this context, we have recently developed the cooperative Rh(II)/Pd(0) dual catalytic systems, which have been utilized for the preparation of carbo- and heterocyclic compounds through the reaction between Rh(II)-carbenoid and π-allyl Pd(II)-complex intermediates in either synergistic or tandem relay catalysis. In synergistic Rh(II)/Pd(0) dual catalysis, the two reactive intermediates are generated simultaneously, which then undergo formal [6+3] dipolar cycloaddition to afford medium-sized N,O-heterocyclic compounds. On the other hand, tandem relay dual catalysis can be enabled through judicious choice of reaction parameters, which proceed through the insertion of Rh(II)-carbenoid into O–H or C–H bonds, followed by Pd(0)-catalyzed allylation to provide allylated benzofused cyclic compounds or chiral β-lactam derivatives.

C,C- and C,N-Chelated Organocopper Compounds

Copper-catalyzed and organocopper-involved reactions are of great significance in organic synthesis. To have a deep understanding of the reaction mechanisms, the structural characterizations of organocopper intermediates become indispensable. Meanwhile, the structure-function relationship of organocopper compounds could advance the rational design and development of new Cu-based reactions and organocopper reagents. Compared to the mono-carbonic ligand, the C,N- and C,C-bidentate ligands better stabilize unstable organocopper compounds. Bidentate ligands can chelate to the same copper atom via η2-mode, forming a mono-cupra-cyclic compounds with at least one acute C-Cu-C angle. When the bidentate ligands bind to two copper atoms via η1-mode at each coordinating site, the bimetallic macrocyclic compounds will form nearly linear C-Cu-C angles. The anionic coordinating sites of the bidentate ligand can also bridge two metals via μ2-mode, forming organocopper aggregates with Cu-Cu interactions and organocuprates with contact ion pair structures. The reaction chemistry of some selected organocopper compounds is highlighted, showing their unique structure–reactivity relationships.

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

The synthesis of complex cyclic compounds is extremely challenging for organic chemists. Many transition-metal-salt-mediated cyclizations are reported in literature. Hg(II) salts have been successfully employed in cyclizations to form complex heterocyclic and carbocyclic structures that are impossible to synthesize with other transition metal salts. In this review, we have summarized cyclization reactions that are performed with Hg(II) salts. These salts are also successfully applied in stoichiometric or catalytic amounts to form complex cyclic structures and natural products.