Transition metal catalyzed element–element′ additions to alkynes

The efficient and stereoselective synthesis of, or precursors to, multi-substituted alkenes has attracted substantial interest due to their existence in various industrially and biologically important compounds. One of the most atom economical routes to such alkenes is the transition metal catalyzed hetero element–element′ π-insertion into alkynes. This article provides a thorough up-to-date review on this area of chemistry, including discussions on the mechanism, range of Esingle bondE′ bonds accessible and the stoichiometric/catalytic transition metal mediators employed

Metal-based glycoconjugates for the targeted anticancer chemotherapy

Rapidly dividing tumor cells require higher amounts of nutrients and energy to sustain their abnormal proliferation rates, and glucose is no exception. Glucose enters the cell by facilitated diffusion through the glucose transporters (GLUTs) and, subsequently, undergoes a series of biochemical steps to produce energy mostly through the highly efficient oxidative phosphorylation process in mitochondria (36 ATPs produced per molecule of glucose) in normal cells. On the contrary, aerobic glycolysis was proved to be the major glucose metabolic pathway in tumor sites (the so-called “Warburg effect”) which is less efficient (4 ATPs/glucose) but occurring at a faster rate. Consequently, cancer cells over-express GLUTs to facilitate glucose internalization in order to satisfy their greater demand for energy. Such increased need for glucose by cancer cells makes it very attractive to selectively target tumor sites. In particular, tailored glucose-like substrates can be conjugated to chemotherapeutics (including metallodrugs) to attain the site-specific intracellular drug transfer and delivery by taking advantage of the over-expression of GLUTs in cancer cells. Within the field of metal-based anticancer agents, some metal-dithiocarbamato complexes have previously shown outstanding in vitro and in vivo antitumor activity together with negligible systemic and organ toxicity (owing to the intrinsic chemoprotective function of the coordinated dithiocarbamato moiety), although selective tumor targeting is still a major issue. On the basis of the aforementioned considerations, the present PhD research work has been focusing on the design of metal-dithiocarbamato glycoconjugates which can combine the antitumor properties and the favorable toxicological profile of the metal-dithiocarbamato scaffold, along with an improved selectivity and cellular uptake provided by the glucose-containing ligands coordinated to the metal center, through the exploitation of the glucose-mediated cellular internalization provided by GLUTs. Specifically, a complete set of Au(I)-, Au(III)- and Pt(II)- dithiocarbamato derivatives of D- and L-glucose has been generated, as well as their nonglycosylated analogues. All complexes have been fully characterized by IR, NMR and UV-Vis spectroscopy, and their stability in solution (DMSO and PBS) and lipophilicity have been evaluated. Preliminary in vitro cytotoxicity studies have been carried out towards a panel of human tumor cell lines, showing that the inclusion of a glucose-like scaffold decreases the antiproliferative activity of the metal-dithiocarbamato core. Interestingly, the D-glucose derivatives generally exhibit greater cytotoxicity than their L-glucose counterparts, which seems to support the hypothesis of the involvement (at least to some extent) of GLUTs in their cell internalization mechanism. However, further in vitro tests carried out in presence of specific GLUTs inhibitors proved somewhat inconclusive.2025-08-2

Tandem Si–Si and Si–H Activation of 1,1,2,2-Tetramethyldisilane by Gold Nanoparticles in Its Reaction with Alkynes: Synthesis of Substituted 1,4-Disila-2,5-cyclohexadienes

The Au/TiO₂-catalyzed reaction between 1,1,2,2-tetramethyldisilane and terminal alkynes yields substituted 1,4-disila-2,5-cyclohexadienes (1,1,4,4-tetramethyl-1,4-dihydro-1,4-disilines) in moderate to good yields. The reaction proceeds via initial Si–Si activation of disilane by gold nanoparticles to form with alkynes isolable <i>cis</i>-1,2-disilyl adducts (<i>cis</i>-1,2-bis­(dimethyl­silyl)­ethenes), which, under the reaction conditions, undergo a Au-catalyzed dehydrogenative cycloaddition to a second alkyne molecule, forming the final cycloadducts

Partial Reduction and Selective Transfer of Hydrogen Chloride on Catalytic Gold Nanoparticles.

HCl in solution accepts electron density from Au NPs and partially reduces at room temperature, as occurs with other simple diatomic molecules, such as O2 and H2 . The activation can be run catalytically in the presence of alkynes to give exclusively E-vinyl chlorides, after the regio- and stereoselective transfer of HCl. Based also on this method, vinyl chloride monomer (VCM) can be produced in a milder and greener way than current industrial processes