Synthesis of Bifunctional Silsesquioxanes (RSiMe₂O)_∼4(R′SiMe₂O)_∼4Si₈O₁₂ via Hydrosilylation of Alkenes

Abstract

In this paper, the effective functionalization of silsesquioxane (HSiMe 2 O) 8 Si 8 O 12 (1) via hydrosilylation of two different functional alkenes is presented. For the first time, such a wide spectrum of statistically bifunctional silsesquioxanes (RSiMe 2 O) ∼4 (R′SiMe 2 O) ∼4 Si 8 O 12 was obtained and characterized. Seventeen new systems with various substituents (Si−H, hydroxyl, ester, epoxy, alkenyl, or alkyl) were prepared by two synthetic approaches. The first method was based on the subsequent hydrosilylation of two alkenes in a one-pot manner, whereas the second one consisted of a twos t e p p r o t o c o l i n w h i c h i n t e r m e d i a t e s ( R S i -Me 2 O) ∼4 (HSiMe 2 O) ∼4 Si 8 O 12 were isolated and then reacted with the second alkene, in the presence of the same or a different catalyst. Resulting systems due to the presence of two various groups attached to the silsesquioxane cage can be considered as potential cores for the synthesis of (hyper)branched molecules or macromolecules.

Formation of Bifunctional Octasilsesquioxanes via Silylative Coupling and Cross-Metathesis Reaction

“…In all cases, the conversion of the initial OVS was estimated at >99%, which was proven by 1 H NMR analysis. The statistical substitution of two types of styrenes is observed in each reaction mixture sample, which is also consistent with the literature [ 7 , 8 , 12 ]. The respective MALDI-TOF analyses that were performed for each reaction sample revealed the presence of a signal assigned to the desired product (of the depicted stoichiometry—respectively abbreviated), accompanied by signals identified as the product of higher and lower values of the desired substitution.…”

“…The presence of all substitution products and their respective ratio in each sample was presented in ESI. The observation of the presence of products with the statistical distribution of the functional moieties is not surprising, due to previous scientific reports that prove that the control of precise vertices’ functionalization may usually be problematic [ 7 , 8 , 12 , 28 ].…”

“…The simple functionalization of the inorganic core, as well as of the organic moieties attached to it, allows one to create various structures and to control the properties of the obtained materials. Among the highly valuable synthetic procedures for the functionalization of silsesquioxanes (SQs), we can list Heck coupling [ 3 , 4 , 5 ], Sonogashira coupling [ 6 ], hydrosilylation [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ], cross-metathesis (CM) [ 16 , 17 , 18 , 19 ], silylative coupling (SC) [ 20 ], O -silylation [ 21 , 22 ] and Friedel–Crafts [ 23 ]. They are all dependent on the type of the functional group attached to the Si–O–Si (SiHC=CH 2 , SiH SiOH).…”

“…However, the reports on this are still limited in the literature. Nevertheless, hydrosilylation remains one of the most useful methods for obtaining bifunctional silsesquioxanes, and it has been the subject of multiple research papers [ 7 , 8 , 10 , 12 ]. Heck coupling [ 28 , 29 , 30 , 31 ] and condensation reactions [ 32 , 33 , 34 , 35 , 36 ] were also applied in this type of synthesis.…”

Novel Silsesquioxane-Derived Boronate Esters—Synthesis and Thermal Properties

“…Functionalization of octahydrosilisesquioxane (SS-8H) and monohydrosilsesquioxane (iBu 7 SS-H) by hydrosilylation reactions has been reported in many publications and patents [ 32 , 33 , 34 , 35 , 36 ]. To the best of our knowledge, so far no one has undertaken functionalizing this type of compounds with vinylboranes by catalytic hydrosilylation reaction.…”