B(C6F5)3-Catalyzed Dehydrocoupling of POSS Silanols with Hydrosilanes: A Metal-Free Strategy for Effecting Functionalization of Silsesquioxanes.

We report a highly effective metal-free catalytic procedure for the functionalization of silsesquioxanes via dehydrocoupling of various POSS silanols with hydrosilanes in the presence of commercially available tris(pentafluorophenyl)borane B(C6F5)3. This approach enables the unprecedented one-pot synthesis of valuable silsesquioxane derivatives under mild conditions, with no corrosive byproducts formed in the process.

Copper(ii) triflate-mediated synthesis of functionalized silsesquioxanes via dehydrogenative coupling of POSS silanols with hydrosilanes.

In light of the fact that the design of new catalytic routes leading to functionalized silsesquioxanes is currently of high relevance; herein we report a novel, highly effective and convenient catalytic approach for the modification of silsesquioxanes. We present a dehydrogenative coupling reaction of completely as well as incompletely condensed POSS silanols with a wide range of commercially available hydrosilanes mediated by inexpensive copper(ii) trifluoromethanesulfonate. This research also includes mechanistic studies for this process.

Ru-Catalyzed Dehydrogenative Silylation of POSS-Silanols with Hydrosilanes: Its Introduction to One-Pot Synthesis.

A commercially available and stable ruthenium dodecacarbonyl catalyst (Ru3(CO)12) allows very efficient and convenient access to functionalized silsesquioxanes (SQs) containing siloxane moiety (Si-O-Si) via dehydrogenative coupling of POSS-silanols with hydrosilanes. With the aid of SiH-containing silsesquioxanes, an unprecedented one-pot procedure has been revealed, and the usefulness of this approach was demonstrated by the synthesis of various derivatives via O-silylation, as well as C═C and C═N hydrosilylation.

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.

Highly Efficient Catalytic Route for the Synthesis of Functionalized Silsesquioxanes.

Silsesquioxanes (POSS) have recently become the subject of growing interest in many branches of materials chemistry. Despite this great interest, no direct metal-catalyzed method to cap the corner of the POSS molecules has yet been proposed. In this report, we present a highly efficient method for the synthesis of functionalized silsesquioxanes mediated by scandium(III) triflate, which opens up the possibility of introducing a wide variety of functional groups into this class of organosilicon compounds under mild conditions with excellent yields. We also investigated the differences in the activity of the Lewis acid (Sc(OTf)3) and the hidden Brønsted acid (TfOH) generated in situ from triflates as catalysts in the functionalization of silsesquioxanes. What is more, this solution provides an efficient corner-capping reaction and other functionalizations to obtain silsesquioxane derivatives which are often not possible to synthesize with good yields, efficiency, and chemoselectivity using conventional methods.

The crucial elements of the 'last step' of programmed cell death induced by kinetin in root cortex of V. faba ssp. minor seedlings.

KEY MESSAGE: Kinetin-induced programmed cell death, manifested by condensation, degradation and methylation of DNA and fluctuation of kinase activities and ATP levels, is an autolytic and root cortex cell-specific process. The last step of programmed cell death (PCD) induced by kinetin in the root cortex of V. faba ssp. minor seedlings was explained using morphologic (nuclear chromatin/aggregation) and metabolic (DNA degradation, DNA methylation and kinases activity) analyses. This step involves: (1) decrease in nuclear DNA content, (2) increase in the number of 4',6-diamidino-2-phenylindole (DAPI)-stained chromocenters, and decrease in chromomycin A3 (CMA3)-stained chromocenters, (3) increase in fluorescence intensity of CMA3-stained chromocenters, (4) condensation of DAPI-stained and loosening of CMA3-stained chromatin, (5) fluctuation of the level of DNA methylation, (6) fluctuation of activities of exo-/endonucleolytic Zn(2+) and Ca(2+)/Mg(2+)-dependent nucleases, (7) changes in H1 and core histone kinase activities and (8) decrease in cellular ATP amount. These results confirmed that kinetin-induced PCD was a specific process. Additionally, based on data presented in this paper (DNA condensation and ATP depletion) and previous studies [increase in vacuole, increase in amount of cytosolic calcium ions, ROS production and cytosol acidification "in Byczkowska et al. (Protoplasma 250:121-128, 2013)"], we propose that the process resembles autolytic type of cell death, the most common type of death during development of plants. Lastly, the observations also suggested that regulation of these processes might be under control of epigenetic (methylation/phosphorylation) mechanisms.