The chemistry of the carbon-transition metal double and triple bond: Annual survey covering the year 2017

Diastereoselective Synthesis of Cyclopropanes from Carbon Pronucleophiles and Alkenes

Cyclopropanes are desirable structural motifs with valuable applications in drug discovery and beyond. Established alkene cyclopropanation methods give rise to cyclopropanes with a limited array of substituents, are difficult to scale, or both. Herein, we disclose a new cyclopropane synthesis through the formal coupling of abundant carbon pronucleophiles and unactivated alkenes. This strategy exploits dicationic adducts derived from electrolysis of thianthrene in the presence of alkene substrates. We find that these dielectrophiles undergo cyclopropanation with methylene pronucleophiles via alkenyl thianthrenium intermediates. This protocol is scalable, proceeds with high diastereoselectivity, and tolerates diverse functional groups on both the alkene and pronucleophile coupling partners. To validate the utility of this new procedure, we prepared an array of substituted analogs of an established cyclopropane that is en route to multiple pharmaceuticals.

Nitrile formation via dichlorocarbene insertion into the Si–N bond of Ln(iii) bis(trimethylsilyl)amide complexes

Reactions of bis(trimethylsilyl)amino lanthanides and chloroform unprecedently generate the Me3SiCN complexes where the nitrile ligand is formed via insertion of dichlorocarbene into the Si–N bond of the lanthanide precursor.

Highly selective ethenolysis with acyclic-aminooxycarbene ruthenium catalysts

Acyclic carbene–ruthenium catalysts were developed for the ethenolysis. Remarkable catalytic efficiency (turnover numbers of 100 000) and excellent α-olefin selectivity (up to 98%) were exhibited.

Addition of alkynes and osmium carbynes towards functionalized dπ-pπ conjugated systems

The metal-carbon triple bonds and carbon-carbon triple bonds are both highly unsaturated bonds. As a result, their reactions tend to afford cycloaddition intermediates or products. Herein, we report a reaction of M≡C and C≡C bonds that affords acyclic addition products. These newly discovered reactions are highly efficient, regio- and stereospecific, with good functional group tolerance, and are robust under air at room temperature. The isotope labeling NMR experiments and theoretical calculations reveal the reaction mechanism. Employing these reactions, functionalized dπ-pπ conjugated systems can be easily constructed and modified. The resulting dπ-pπ conjugated systems were found to be good electron transport layer materials in organic solar cells, with power conversion efficiency up to 16.28% based on the PM6: Y6 non-fullerene system. This work provides a facile, efficient methodology for the preparation of dπ-pπ conjugated systems for use in functional materials.

New chalcone-substituted metallophthalocyanines: Synthesis, characterization, and investigation of their properties

The synthesis of novel metallophthalocyanines (M = Zn, Mg, and Co) derived from ( E)-3-(3-bromophenyl)-1-(3-hydroxyphenyl)prop-2-en-1-one and ( E)-3-(3-fluorophenyl)-1-(3-hydroxyphenyl)prop-2-en-1-one is achieved. These complexes and the synthesized novel phthalonitrile derivatives are characterized by FTIR, 1H NMR, 13C NMR, UV-Vis, mass spectrometry, and elemental analysis. The aggregation properties of the metallophthalocyanines ZnPc, MgPc, and CoPc are investigated in different solvents and at different concentrations in dimethyl formamide. The electrochemical behavior is also investigated. The cyclic voltammograms give one oxidation reaction for all the bromo-derived metallophthalocyanines and one reduction reaction for all the fluoro-derived metallophthalocyanines. Fe3+, Cd2+, Hg2+, Cu2+, Ni2+, and Co2+ ions are titrated fluorometrically with the phthalocyanines. The bromo- and fluoro-substituted phthalocyanine compounds show different effects on the metal ion titrations.

Gold-Catalyzed Homogeneous (Cyclo)Isomerization Reactions

Gold is currently one of the most used metals in organometallic catalysis. The ability of gold to activate unsaturated groups in different modes, together with its tolerance to a wide range of functional groups and reaction conditions, turns gold-based complexes into efficient and highly sought after catalysts. Natural products and relevant compounds with biological and pharmaceutical activity are often characterized by complex molecular structures. (Cyclo)isomerization reactions are often a useful strategy for the generation of this molecular complexity from synthetically accessible reactants. In this review, we collect the most recent contributions in which gold(I)- and/or gold(III)-catalysts mediate intramolecular (cyclo)isomerization transformations of unsaturated species, which commonly feature allene or alkyne motifs, and organize them depending on the substrate and the reaction type.