Cu(I)-Catalyzed Macrocyclic Sonogashira-Type Cross-Coupling

A novel, efficient and magnetically recyclable Cu-Ni bimetallic alloy nanoparticle as a highly active bifunctional catalyst for Pd-free Sonogashira and C-N cross-coupling reactions: a combined theoretical and experimental study

In this study, a Fe3O4@SiO2@Cyt-Ni/Cu nanocomposite as a novel heterogeneous bimetallic catalyst was synthesized which exhibits efficient performance for the Sonogashira and C-N cross-coupling reactions. The characterization of the catalyst was studied by FT-IR, PXRD, VSM, EDX, TEM, FE-SEM and TGA analyses. The geometry optimization and relative energies of the designed bimetallic complexes were theoretically determined using density functional theory (DFT) calculation at the B3LYP/6-31G**/LANL2DZ level. The catalyst showed good activity in the coupling of various aryl halides with alkynes (Sonogashira reaction) as well as aryl halide with N-heterocycles and achieved coupling products with good to high yields for all of them in a short time. The high catalytic performance could be due to the synergistic effect between Ni and Cu, which causes the reaction to proceed more efficiently. This heterogeneous nanocatalyst could be easily recovered from the reaction mixture with an external magnet and reused for 7 consecutive runs with minimal loss of catalytic activity.

Copper-catalyzed deacetonative Sonogashira coupling

A convenient Pd- and phosphine-free protocol for assembling internal alkynes from tertiary propargyl alcohols and (het)aryl halides has been developed. The proposed tandem approach includes the base-promoted retro-Favorskii fragmentation followed by Cu-catalyzed C(sp)-C(sp²) cross-coupling. The use of inexpensive reagents (e.g. a catalyst, additives, a base, and a solvent) and good functional group tolerance make the procedure practical and cost-effective. The synthetic utility of the method was demonstrated by a smooth alkynylation of vinyl iodides derived from natural steroidal hormones.

A.E.Favorskii’s scientific legacy in modern organic chemistry: prototropic acetylene – allene isomerization and the acetylene zipper reaction

Alexei Evgrafovich Favorskii was an outstanding organic chemist who left a great scientific legacy as a result of long time and fruitful work. Most of the theoretically and practically important discoveries of A.E.Favorskii were made in the chemistry of acetylene and its derivatives. Nowadays, the reactions discovered by him, which include acetylene – allene isomerization, the Favorskii and retro-Favorskii reactions, the Favorskii rearrangement and the vinylation reaction, are widely used in industry and in laboratory synthesis. This review summarizes the main scientific achievements of A.E.Favorskii, as well as their development in modern organic chemistry. Much consideration is given to acetylene – allene isomerization as a convenient method for the synthesis of methyl-substituted acetylenes and to the acetylene zipper reaction as a synthetic tool for obtaining terminal acetylenes. The review presents examples of the application of these reactions in modern organic synthesis of complex molecules, including natural compounds and their analogues.

The bibliography includes 266 references.

Synthesis of macrocyclic peptidomimetics via the Ugi-click-strategy

The Ugi-click-strategy was employed for the synthesis of 12–28 membered 1,2,3-triazole derived macrocyclic peptidomimetics.

A highly efficient nano-sized Cu2O/SiO2egg-shell catalyst for C–C coupling reactions

Mesoporous SiO₂-supported Cu₂O nanoparticles as an egg-shell type catalyst were prepared by impregnation method. The obtained Cu₂O/SiO₂ egg-shell nanocatalyst had a large surface area and narrow pore size distribution. In addition, most of the Cu₂O nanoparticles, with sizes around 2.0 nm, were highly dispersed in the mesoporous silica. Accordingly, fast reactant diffusion to the active sites would occur, especially when the active metal sites are selectively located on the outer part of the support, i.e., the outer region of the egg shell. In solvent-free Sonogashira reactions for the synthesis of ynones from acyl chlorides and terminal alkynes, this catalyst exhibited a very high catalytic activity. The excellent catalytic performance can be attributed to the synergistic advantages of mesoporous structure and monodispersed Cu₂O nanoparticles.

Mesoporous SiO₂-supported Cu₂O nanoparticles as an egg-shell type catalyst were prepared by impregnation method.

Synthesis of [2]Catenanes by Intramolecular Sonogashira-Type Reaction

The catalytic activity of macrocyclic phenanthroline-CuI complexes was utilized to synthesize [2]catenanes by intramolecular Sonogashira-type reaction. The high reactivity of the acyclic starting material was critical to synthesize the [2]catenane in acceptable yields. The relationship between the yield of the [2]catenane and the structure of the starting materials was disclosed.

Total Syntheses of (R)-Strongylodiols C and D

The first total syntheses of two marine natural products, (R)-strongylodiols C and D, with 99% ee were achieved. The key steps of the strategy include the zipper reaction of an alkyne, the asymmetric alkynylation of an unsaturated aliphatic aldehyde catalyzed with Trost's ProPhenol ligand, and the Cadiot-Chodkiewicz cross-coupling reaction of a chiral propargylic alcohol with a bromoalkyne.

Exo-selective reductive macrocyclization of ynals

A general protocol for the highly exo-selective macrocyclization of ynals using a nickel/N-heterocyclic carbene catalyst system has been developed. A series of 10- to 21-membered macrocycles bearing an exomethylene substituent was synthesized in good yields with excellent regioselectivity (exo/endo >95:5). Very high levels of long-range diastereocontrol can also be achieved for some classes of macrocycles. Complementary to previously reported endo-selective macrocyclizations, this method provides accesses to exoalkylidene macrocycles from simple ynals in high selectivity.

Copper-catalysed cross-coupling: an untapped potential

Copper is emerging as a viable catalytic metal for cross-coupling reactions to construct carbon–carbon (C–C) bonds.