The development of reactions that convert alcohols into important chemical compounds saves our fossil carbon resources as alcohols can be obtained from indigestible biomass such as lignocellulose. The conservation of our rare noble metals is of similar importance, and their replacement by abundantly available transition metals, such as Mn, Fe, or Co (base or nonprecious metals), in key technologies such as catalysis is a promising option. Herein, we report on the first base-metal-catalyzed synthesis of pyrroles from alcohols and amino alcohols. The most efficient catalysts are Mn complexes stabilized by PN P ligands whereas related Fe and Co complexes are inactive. The reaction proceeds under mild conditions at catalyst loadings as low as 0.5 mol %, and has a broad scope and attractive functional-group tolerance. These findings may inspire others to use Mn catalysts to replace Ir or Ru complexes in challenging dehydrogenation reactions.
An original family of well-defined molecular and macromolecular double-decker silsesquioxane derivatives with ethyl bridged π-conjugated arenes is obtained via hydrosilylation reaction.
Vinyl-trisubstituted germanes react selectively with terminal alkynes in the presence of compounds containing Ru-H and Ru-Ge bonds with formation of functionalized alkynylgermanes. The reaction opens the first transition metal catalytic route for the preparation of this class of organogermanes, which are useful reagents for organic synthesis. The mechanism elucidated by NMR spectroscopic study of stoichiometric reactions shows that this process is a new catalytic activation of an sp-hybridized C-H bond involving the previously discovered activation of the dC-Ge bond. † Dedicated to Professor Florian Domka on the occasion of his 75th birthday.
Over the past two decades, organic optoelectronic materials have been considered very promising. The attractiveness of this group of compounds, regardless of their undisputable application potential, lies in the possibility of their use in the construction of organic–inorganic hybrid materials. This class of frameworks also considers nanostructural polyhedral oligomeric silsesquioxanes (POSSs) with “organic coronae” and precisely defined organic architectures between dispersed rigid silica cores. A significant number of papers on the design and development of POSS-based organic optoelectronic as well as photoluminescent (PL) materials have been published recently. In view of the scientific literature abounding with numerous examples of their application (i.e., as OLEDs), the aim of this review is to present efficient synthetic pathways leading to the formation of nanocomposite materials based on silsesquioxane systems that contain organic chromophores of complex nature. A summary of stoichiometric and predominantly catalytic methods for these silsesquioxane-based systems to be applied in the construction of photoactive materials or their precursors is given.
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