Synthesis of unsymmetrically and symmetrically functionalized disiloxanes via subsequent hydrosilylation of C≡C bonds

A selective synthesis of unsymmetrically functionalized disiloxanes via the subsequent hydrosilylation of internal alkynes in the first step, and alkynes (terminal or internal) or 1,3-diynes in the second, with 1,1,3,3-tetramethyldisiloxane (1) is presented for the first time. Using developed approaches performed in a stepwise or one-pot manner a new family of disubstituted disiloxanes was obtained which had previously been inaccessible by other synthetic methods. Moreover, symmetrically functionalized disiloxanes were obtained by direct hydrosilylation of 2 equivalents of terminal or internal alkynes with 1, showing the unique versatility of the hydrosilylation process. Three examples of symmetric disiloxanes were characterized by single crystal X-ray diffraction for the first time. As a result, a wide group of new compounds which can find potential applications as building blocks or coupling agents was obtained and characterized.

Directed cis-hydrosilylation of borylalkynes to borylsilylalkenes

Directed by the choice of catalyst cis-hydrosilylation of borylalkynes leads to novel borylsilylalkenes which are crucial synthons for the introduction of the carbon–carbon double bonds in organic synthesis.

Alkenyl-Functionalized Open-Cage Silsesquioxanes (RSiMe2O)3R'7Si7O9: A Novel Class of Building Nanoblocks

Trifunctional incompletely condensed polyhedral oligomeric silsesquioxanes (RSiMe₂O)₃R′₇Si₇O₉ (IC-POSSs) are considered as intriguing building nanoblocks dedicated to constructing highly advanced organic–inorganic molecules and polymers. Up to now, they have been mainly obtained via hydrosilylation of olefins, while the hydrosilylation of the C≡C bonds has not been studied at all, despite the enormous potential of this approach resulting from the possibility of introducing 3, 6, or even more functional groups into the IC-POSS structure. Therefore, in this work, we present a highly selective and efficient synthesis of the first example of tripodal alkenyl-functionalized IC-POSSs, obtained via platinum-catalyzed hydrosilylation of the terminal and internal alkynes, as well as symmetrically and nonsymmetrically 1,4-disubstituted buta-1,3-diynes with silsesquioxanes (HSiMe₂O)₃R′₇Si₇O₉ (R′ = i-C₄H₉ (1a), (H₃C)₃CH₂C(H₃C)HCH₂C (1b)). The resulting products are synthetic intermediates that contain C=C bonds and functional groups (e.g., OSiMe₃, SiR₃, Br, F, B(O(C(CH₃)₂)₂ (Bpin)), thienyl), which make them suitable for application in the synthesis of novel, complex, hybrid materials with unique properties.

The first example of the synthesis of alkenyl-functionalized open-cage silsesquioxanes (IC-POSS) via platinum-catalyzed hydrosilylation of C−C triple bonds in alkynes and buta-1,3-diynes is presented. The optimized synthetic procedure allowed for the selective and efficient synthesis of 20 new functional molecules capable of further modification by hydrosilylation, hydroboration, or other chemical processes.

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

Bifunctional silsesquioxanes create an attractive group of compounds with a wide range of potential applications, and recently they have gained much interest. They are known to be obtained mainly via hydrosilylation, but we disclose novel synthetic protocols based on different but complementary reactions, i.e., cross-metathesis (CM) and silylative coupling (SC). A series of cubic T₈ type silsesquioxane derivatives with a broad scope of styryl substituents were synthesized in a one-pot procedure and characterized by spectroscopic and spectrometric methods. All of the new compounds can be obtained in a one-pot manner, which has an attractive impact on the synthetic procedure, as it is economic in terms of the isolation of intermediate products. Additionally, the methodology disclosed here enables the (E)-stereoselective introduction of styrenes derivative to the cubic T₈ type core. The presented compounds can be interesting precursors for a further functionalization that may significantly increase the possibility of their application in the design and synthesis of new functional materials.

Synthesis of Bifunctional Silsesquioxanes and Spherosilicates with Organogermyl Functionalities

In this paper we present the synthesis of mixed bifunctional compounds of T₈ H₈ silsesquioxane and spherosilicate (HSiMe₂ O)₈ Si₈ O₁₂ derivatives via platinum-catalyzed hydrosilylation of alkenylgermanes and olefins. To the best of our knowledge, this is the first literature example of bifunctional compounds with organogermyl functionalities. Eleven mixed systems with a variety of substituents (Si-H, alkyl, germyl, epoxy, and hydroxy) were prepared and fully characterized by NMR spectroscopy. Additionally, our research includes a real-time FT-IR study of the synthesis of these bifunctional compounds of the general formula (R)_8-m (GeR'₃ (CH₂ )_n+2 R)_m Si₈ O₁₂ . and (R''(CH₂ )₂ R)_8-m (GeR'₃ (CH₂ )₂ R)_m Si₈ O₁₂ where m∼4.

Dialkenylgermanes as Precursors of Silsesquioxane-based Macromolecular Structures

Herein we report a study of highly efficient platinum-catalyzed hydrosilylation of dialkenylgermanes with silsesquioxanes and spherosilicates. The use of divinyl- and diallylgermanes allowed the synthesis of new classes of compounds, i. e., dumbbell-type systems, silsesquioxanes with alkenyl pendant group, and oligomeric derivatives. The results are supported by detailed data from in situ FT-IR and NMR measurements, enabling precise monitoring of the reaction progress and determination of regioselectivity of the formed products.

Introduction of organogermyl functionalities to cage silsesquioxanes

In this work, we present the first example of highly efficient platinum-catalyzed hydrosilylation of vinyl- and allylgermanes with different types of silsesquioxanes and spherosilicates. This protocol allows the straightforward introduction of organogermyl functionalities with alkyl chains linked to the silsesquioxane core with good yields and excellent selectivity. These derivatives may be applied as precursors for the development of advanced hybrid materials in the future. In addition, a comparison made between vinylsilanes and vinylgermanes showed a higher reactivity of germanium compounds in the hydrosilylation reaction. To the best of our knowledge, this is the first literature example of the functionalization of silsesquioxanes and spherosilicates with these types of germanium derivatives. The reaction parameters and kinetics were determined by in situ FT-IR. In addition, our research is supported by extensive data obtained from NMR measurements.

Selective Hydrosilylation of Alkynes with Octaspherosilicate (HSiMe2 O)8 Si8 O12

Comprehensive studies on platinum-catalyzed hydrosilylation of a wide range of terminal and internal alkynes with spherosilicate (HSiMe2 O)8 Si8 O12 (1 a) were performed. The influence of the reaction parameters and the types of reagents and catalysts on the efficiency of the process, which enabled the creation of a versatile and selective method to synthesize olefin octafunctionalized octaspherosilicates, was studied in detail. Within this work, twenty novel 1,2-(E)-disubstituted and 1,1,2-(E)-trisubstituted alkenyl-octaspherosilicates (3 a-m, 6 n-t) were selectively obtained with high yields, and fully characterized (1 H, 13 C, 29 Si NMR, FTIR, MALDI TOF or TOF MS ES+ analysis). Moreover, the molecular structure of the compound (Me3 Si(H)C=C(H)SiMe2 O)8 Si8 O12 (3 a) was determined by X-ray crystallography for the first time. The developed procedures are the first that allow selective hydrosilylation of terminal silyl, germyl, aryl, and alkyl alkynes with 1 a, as well as the direct introduction of sixteen functional groups into the 1 a structure by the hydrosilylation of internal alkynes. This method constituted a powerful tool for the synthesis of hyperbranched compounds with a Si-O based cubic core. The resulting products, owing to their unique structure and physicochemical properties, are considered novel, multifunctional, hybrid, and nanometric building blocks, intended for the synthesis of star-shaped molecules or macromolecules, as well as nanofillers and polymer modifiers. In the presented syntheses, commercially available reagents and catalysts were used, so these methods can be easily repeated, rapidly scaled up, and widely applied.

Introduction of Boron Functionalities into Silsesquioxanes: Novel Independent Methodologies

Owing to their versatile application possibilities, silsesquioxanes (SQs) are of considerable interest for creating hybrid inorganic-organic materials. In this report, two novel and independent strategies for the direct attachment of boron functionalities to silsesquioxanes are presented. Encouraged by our previous work concerning the synthesis of borasiloxanes through the catalyst-free dehydrogenative coupling of silanols and boranes, we decided to apply our method to a synthesis of various boron-functionalized silsesquioxanes. During our tests, we also investigated the activity of scandium(III) triflate, which we have previously used as an excellent catalyst for the obtaining of Si-O-Si and Si-O-Ge moieties. As a result, we also discovered a novel approach for the O-borylation of Si-OH groups in silsesquioxanes with allylborane. Both routes are highly chemoselective and efficiently lead to the obtaining of Si-O-B moiety under air atmosphere and at room temperature.

Synthesis of Monofunctionalized Silsesquioxanes (RSiMe2 O)(iBu)7 Si8 O12 via Alkene Hydrosilylation

The research presented in this work comprehensively describes hydrosilylation of a wide spectrum of alkenes which contain one or more reactive groups with (HSiMe₂ O)(iBu)₇ Si₈ O₁₂ , in the presence of different types of catalysts. Special attention is paid to the influence of alkene, catalyst, and reaction conditions on process effectiveness and selectivity by the precise monitoring of the experiments with in situ FTIR and NMR spectroscopies. More than twenty silsesquioxanes bearing reactive groups (OH, Br, NR₂ , CO, COOR, NCO, epoxy, SiR₃ ) commonly used in organic and polymer chemistry, were obtained, isolated and characterized by ¹ H, ¹³ C, ²⁹ Si NMR and MALDI TOF. Importantly, in the presented syntheses, commercially available reagents and catalysts were used, meaning that the presented methods could be easily repeated, rapidly scaled up, and widely applied.

A library of multisubstituted cyclotriphosphazenes – molecular scaffolds for hybrid materials

An easy pathway for the synthesis of new cyclotriphosphazene derivatives based on a Pt-catalyzed hydrosilylation process and their characterization are presented.