Polyurethane composites based on silsesquioxane derivatives of different structures

Journal of Thermal Analysis and Calorimetry - A series of siloxane–silsesquioxane resins with Q8 structures, as network nodes containing reactive Si–H groups in the siloxane backbone,...     

A highly stereoselective synthesis of new styryl-π-conjugate organosilicon compounds

This work describes very precise and controlled catalytic transformations as useful tools for the synthesis of new trans-π-conjugated molecular and macromolecular organosilicon compounds. Several distyryl-arenes were obtained efficiently via silylative coupling in high yields and with excellent selectivity for new E,E-bis(silyl)arenes.     

Novel Silsesquioxane-Derived Boronate Esters—Synthesis and Thermal Properties

The functionalization of mono- and octahydrospherosilicate with vinylboranes and allylboranes via hydrosilylation reaction in the presence of a Karstedt’s platinum (0) catalyst is presented. This is the catalytic route to obtain a new class of silsesquioxanes containing boron atoms in their structure in high yields (>90%) and with satisfactory selectivity. The obtained compounds were fully characterized by spectroscopic (¹H, ¹³C, ²⁹Si NMR) and spectrometric methods (MALDI-TOF-MS), as well as thermal analysis (TGA). The obtained compounds were subjected to thermal tests, characterizing the processes of melting, thermal evaporation, sublimation and thermal decomposition.     

A new selective approach to 1,1-bis(silyl)-2-arylethenes and 1,1-bis(silyl)-1,3-butadienes via sequential silylative coupling-Heck coupling reactions

A novel selective route to 1,1-bis(silyl)-1-alkenes has been developed. Sequential one-pot silylative coupling exo-cyclization of 1,2-bis(dimethylvinylsiloxy)ethane followed by the reaction with Grignard reagents leads to the desired 1,1-bis(silyl)ethenes, which are then efficiently coupled in the presence of silver nitrate and palladium acetate with aryl or alkenyl idodides to give the corresponding 1,1-bis(silyl)-2-arylethenes or 1,1,4-trisubstituted 1,3-butadienes with high yield.     

Substituent effects of the N,N-dimethyl- sulfamoyl group on the 1H and 13C NMR spectra of positional isomers of quinolines

The complete 1H and 13C NMR spectral assignments of seven positional isomers of N,N-dimethylsulfamoylquinolines 2-8 and quinoline have been made using 1D and 2D NMR techniques, including COSY, HMQC and HMBC experiments. Deltadelta(H) and Deltadelta(C) substituent effects induced by the sulfamoyl group were determined. The sulfamoyl substituent affects proton and carbon chemical shifts both in the parent and in the fused (pyridine or benzene) ring.     

Design,Sustainable Synthesis and Biological Evaluation of a Novel Dual α2A/5-HT7 Receptor Antagonist with Antidepressant-Like Properties

The complex pathophysiology of depression, together with the limits of currently available antidepressants, has resulted in the continuous quest for alternative therapeutic strategies. Numerous findings suggest that pharmacological blockade of α₂-adrenoceptor might be beneficial for the treatment of depressive symptoms by increasing both norepinephrine and serotonin levels in certain brain areas. Moreover, the antidepressant properties of 5-HT₇ receptor antagonists have been widely demonstrated in a large set of animal models. Considering the potential therapeutic advantages in targeting both α₂-adrenoceptors and 5-HT₇ receptors, we designed a small series of arylsulfonamide derivatives of (dihydrobenzofuranoxy)ethyl piperidines as dually active ligands. Following green chemistry principles, the designed compounds were synthesized entirely using a sustainable mechanochemical approach. The identified compound 8 behaved as a potent α_2A/5-HT₇ receptor antagonist and displayed moderate-to-high selectivity over α₁-adrenoceptor subtypes and selected serotonin and dopaminergic receptors. Finally, compound 8 improved performance of mice in the forced swim test, displaying similar potency to the reference drug mirtazapine.     

Catalysis of hydrosilylation XIII. Gas-phase hydrosilylation of acetylene by trichlorosilane on functionalised silica supported rhodium and ruthenium phosphine complexes

Gas-phase hydrosilylation of acetylene by tri-chlorosilane catalyzed in a continuous flow apparatus by rhodium and ruthenium phosphine complexes immobilized on the silica via mercapto, phosphine, amine and nitrile ligands has been studied. GLC analysis of the reaction products showed vinyltrichlorosilane to be accompanied by products of double hydrosilylation of acetylene and the redistribution of trichlorosilane followed by the hydrosilylation and hydrogenative hydrosilylation of acetylene with dichlorosilane. A scheme for this complex competitive–consecutive reaction was proposed. The yield and selectivity of vinyltrichlorosilane can be much improved under special reaction conditions, e.g. rate flow of the particular substrates, temperature, given catalyst and others. Kinetic measurements carried out in the range of 115–140°C allowed us to evaluate the activation energy, E_a, for the vinyltrichlorosilane synthesis, which varied between 20.5 and 27.6 kJ mol^?1 for the selected rhodium and ruthenium supported complexes.     

Modification of (Poly)Siloxanes via Hydrosilylation Catalyzed by Rhodium Complex in Ionic Liquids

The hydrosilylation of 1-heptene, allyl glycidyl ether and, allyl polyether by heptamethylhydrotrisiloxane and poly(hydro, methyl)(dimethyl)siloxane catalyzed by rhodium(I) complexes (particularly [{Rh(μ–OSiMe₃)(cod)}₂]) in imidazolium ionic liquids (especially [TriMIM]MeSO₄) gives heptyl and glycidyloxy functional (poly)siloxanes and silicone polyethers with high yield and selectivity. The catalytic system based on rhodium siloxide can be easily separated from the product and successfully reused up to five times.     

Stereoselective synthesis of amides possessing a vinylsilicon functionality via a ruthenium catalyzed silylative coupling reaction

An effective stereoselective synthesis of E-N-2-(silyl)vinylamides via silylative coupling of vinyl amides such as N-vinylpyrrolidinone, N-vinylphthalimide, and N-vinylformamide with vinyltrisubstituted silanes catalyzed by [RuH(Cl)(CO)(PCy₃)₂] I is described.     

Synthesis of functionalized vinylgermanes through a new ruthenium-catalyzed coupling reaction

Vinyl-substituted germanes react stereo- and regioselectively with olefins in the presence of complexes containing Ru-H and Ru-Ge bonds with the formation of functionalized vinylgermanes that cannot be synthesized by olefin cross-metathesis procedures. The reaction opens a new catalytic route for preparation of a class of organogermanes that are potent organometallic reagents for organic synthesis because they show very low toxicity and could replace organotin compounds. The mechanism of this new catalytic route was proven to involve an interesting insertion of the vinylgermane into the Ru-H bond and beta-Ge transfer to the metal with elimination of ethylene and generation of an Ru-Ge bond, followed by insertion of the alkene into the Ru-Ge bond and beta-H transfer to the metal to eliminate the substituted vinylgermane.