Tris Trimethylsilyl Silane Research Articles

Light-Mediated Synthesis of 2-(4-Methoxyphenyl)-1-pyrroline via Intramolecular Reductive Cyclization of a Triplet Alkylnitrene.

Irradiation of p-methoxyazidobutyrophenone (1) in methanol yielded 2-(4-methoxyphenyl)-1-pyrroline (2) and several other photoproducts. However, in the presence of tris(trimethylsilyl)silane (TTMSS), 2 is formed selectively. Transient absorption and ESR spectroscopy verify that the irradiation of 1 forms triplet alkylnitrene 31N through intramolecular energy transfer from the triplet ketone (T1K). DFT calculations indicate that 31N abstracts H atoms from TTMSS but not methanol, which explains the selectivity. Thus, triplet alkylnitrenes can undergo selective reductive cyclization via H atom abstraction from TTMSS.

Physicochemical properties of experimental resin-based composites using tris(trimethylsilyl)silane associated with diphenyl iodonium hexafluorophosphate (DPIHP) salt

The purpose was to evaluate the effect of tris(trimethylsilyl)silane (TTMSS) associated with diphenyl iodonium hexafluorophosphate (DPIHP) on the polymerization shrinkage stress (PSS), mechanical properties, color change (CC), and degree of conversion (DC) of resin-based composites (RBCs). Experimental RBCs containing 35 wt% of organic matrix (10.2 wt% BisGMA, 11.1 wt% BisEMA10 and UDMA and 2.1 wt% TEGDMA) and 65 wt% filler (13 wt% fumed silica and 52 wt% BaBSiO2) were assigned to six groups: control (0.2 wt% CQ, 0.5 wt% DMAEMA); TD05 (0.2 wt% CQ, 0.5 wt% TTMSS, 0.5 wt% DPIHP); TD10 (0.2 wt% CQ, 1 wt% TTMSS, 0.5 wt% DPIHP); DTD (0.2 wt% CQ, 0.25 wt% of DMAEMA, 0.25 wt% TTMSS, 0.5 wt% DPIHP); DT (0.2 wt% CQ, 0.25 wt% DMAEMA, 0.25 wt% TTMSS); and T05 (0.2 wt% CQ, 0.25 wt% TTMSS). The experimental formulations were submitted to the following tests: DC; PSS; CC; rate of polymerization (Rp); depth of cure by Knoop hardness; flexural strength; and flexural modulus. TTMSS showed no effect on the DC, Rp, and mechanical properties of the RBCs. DMAEMA reacted with TTMSS and reduced the Rp; the RBCs containing no DMAEMA showed no reduction in CC. DT showed the lowest PSS mean value among the groups. TTMSS differed from DMAEMA only when used in combination with DPIHP, which significantly improved the DC, maximum Rp, and mechanical properties of the RBCs tested. Based on the artificial ageing results, TTMSS was ineffective in reducing CC in the RBCs tested.

Descumming fluorous solution for photolithographic patterning of organic light-emitting diodes

Orthogonal processing is a photolithographic patterning method using fluorous solvents and highly fluorinated photoresists; it has shown potential as a unique patterning protocol that can form high-resolution structures while minimizing damage to the thin films of organic electronic materials. In this study, we adopted the technique to the photo-patterning of 15 μm half-pitch organic light-emitting diode (OLED) pixels on a 4,4′,4»-tri(N-carbazolyl)triphenylamine (TCTA) thin film that forms a hole-transporting layer (HTL). However, the device patterned using the highly fluorinated materials system showed a lower driving voltage and reduced efficiency compared to the non-patterned device. This problem was presumed to be caused by the attachment of strong acid molecules generated from the photo-patterning process and residues of the highly fluorinated photoresist to the TCTA surface. To remove this scum layer and to restore the performance of the TCTA, a solution-based rinsing process was devised and performed onto the TCTA layer by adding a trace amount of (dimethylamino)trimethylsilane (DMTS) and tris(trimethylsilyl)silane (TTMSS) to a fluorous solvent. As a result, the driving voltage and efficiency of the patterned OLED device were restored to similar levels to those of the non-patterned reference. Observation of the patterned TCTA layer with an atomic force microscope (AFM) gave an idea that the morphology of the patterned TCTA film was changed to be similar to that of the pristine TCTA film after the solution-based rinsing process. Furthermore, X-ray photoelectron spectroscopy (XPS) also verified that the solution containing descumming agents reduced the fluorine residue on the TCTA surface. This result demonstrated that the solution-based descumming process is an effective approach to increase the device performance during the photolithographic patterning of OLEDs to which typical dry etching-based descumming may not be applied.

Cross-coupling of sulfonic acid derivatives via aryl-radical transfer (ART) using TTMSS or photoredox

The intramolecular cross-coupling of sulfonic acid derivatives occurs in the presence of tris(trimethylsilyl)silane (TTMSS) at room temperature and in air to form biaryl compounds. A photoredox-catalyzed procedure is also described. These protocols provide mild and convenient alternatives to standard tin-mediated reactions.

Tris(trimethylsilyl)silane as a co-initiator for dental adhesive: Photo-polymerization kinetics and dynamic mechanical property

ObjectivesThe purpose of this study was to evaluate the polymerization behavior of a model dentin adhesive with tris(trimethylsilyl)silane (TTMSS) as a co-initiator, and to investigate the polymerization kinetics and mechanical properties of copolymers in dry and wet conditions. MethodsA co-monomer mixture based on HEMA/BisGMA (45/55, w/w) was used as a model dentin adhesive. The photoinitiator system included camphorquinone (CQ) as the photosensitizer and the co-initiator was ethyl-4-(dimethylamino) benzoate (EDMAB) or TTMSS. Iodonium salt, diphenyliodonium hexafluorophosphate (DPIHP) serving as a catalyst, was selectively added into the adhesive formulations. The control and the experimental formulations were characterized with regard to the degree of conversion (DC) and dynamic mechanical properties under dry and wet conditions. ResultsIn two-component photoinitiator system (CQ/TTMSS), with an increase of TTMSS concentration, the polymerization rate and DC of CC double bond increased, and showed a dependence on the irradiation time and curing light intensity. The copolymers that contained the three-component photoinitiator system (CQ/TTMSS/DPIHP) showed similar dynamic mechanical properties, under both dry and wet conditions, to the EDMAB-containing system. SignificanceThe DC of formulations using TTMSS as co-initiator showed a strong dependence on irradiation time. With the addition of TTMSS, the maximum polymerization rate can be adjusted and the network structure became more homogenous. The results indicated that the TTMSS could be used as a substitute for amine-type co-initiator in visible-light induced free radical polymerization of methacrylate-based dentin adhesives.

Development of methacrylate/silorane hybrid monomer system: Relationship between photopolymerization behavior and dynamic mechanical properties.

Resin chemistries for dental composite are evolving as noted by the introduction of silorane-based composites in 2007. This shift in the landscape from methacrylate-based composites has fueled the quest for versatile methacrylate-silorane adhesives. The objective of this study was to evaluate the polymerization behavior and structure/property relationships of methacrylate-silorane hybrid systems. Amine compound ethyl-4-(dimethylamino) benzoate (EDMAB) or silane compound tris(trimethylsilyl) silane (TTMSS) was selected as coinitiators. The mechanical properties of the copolymer were improved significantly at low concentrations (15, 25, or 35 wt %) of silorane when EDMAB was used as coinitiator. The rubbery moduli of these experimental copolymers were increased by up to 260%, compared with that of the control (30.8 ± 1.9 MPa). Visible phase separation appeared in these formulations if the silorane concentrations in the formulations were 50-75 wt %. The use of TTMSS as coinitiator decreased the phase separation, but there was a concomitant decrease in mechanical properties. In the neat methacrylate formulations, the maximum rates of free-radical polymerization with EDMAB or TTMSS were 0.28 or 0.06 s(-1) , respectively. In the neat silorane resin, the maximum rates of cationic ring-opening polymerization with EDMAB or TTMSS were 0.056 or 0.087 s(-1) , respectively. The phase separation phenomenon may be attributed to differences in the rates of free-radical polymerization of methacrylates and cationic ring-opening polymerization of silorane. In the hybrid systems, free-radical polymerization initiated with EDMAB led to higher crosslink density and better mechanical properties under dry/wet conditions. These beneficial effects were, however, associated with an increase in heterogeneity in the network structure. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 841-852, 2016.

ChemInform Abstract: Tris(trimethylsilyl)silane (TTMSS): Formation of Carbon-Centered Radicals from Oxathiolane and Thiazolidine Derivatives.

Abstract Tris(trimethylsilyl)silane (TTMSS) is an efficient reagent for the formation of carbon-centered radicals from 1,3-oxathiolane, 5-oxo-1,3-oxathiolane, N(methylcarbonyl)-1,3-thiazolidine and N(ethoxycarbonyl)-1,3- thiazolidine derivatives by the selective cleavage of the carbon-sulphur bond.

Alkene-allenecyclopropane radical cyclisations promoted by tris-(trimethylsilyl)silane

Treatment of the butenyl-substituted allenecyclopropanes 5 and 12 with tris -(trimethylsilyl)silane (TTMSS)–AIBN results in facile radical cyclisations into the cyclopropane-carbon centres of the allene moieties, followed by cyclopropane ring-opening and allene isomerisation, leading to the bicyclic 1,3-dienes 10 and 13, respectively. By contrast, treatment of the pentenyl-substituted allenecyclopropane 15a and the iodoethane 18 with TTMSS–AIBN, led to the alkylsilane 16, and the enyne 21, respectively. Desilylation of 10 and 13 gave the corresponding bicyclic hydrocarbons.

Tris(trimethylsilyl)silane promoted radical reaction and electron-transfer reaction in benzotrifluoride

Tris(trimethylsilyl)silane (TTMSS) promoted free radical reaction in benzotrifluoride (BTF) was investigated. Compared to same reaction using environmentally less desirable tri- n-butyltin hydride (TBTH) in benzene, less quantity of BTF than that of benzene can be used because of slower hydrogen atom transfer from TTMSS than that from TBTH toward primary alkyl radicals. Also, electron-transfer reactions promoted by tris( p-bromophenyl)aminium hexachloroantimonate (TBPA) and FeCl 3 were conducted in BTF. Then, TBPA was found to be effective in BTF comparably to that in methylene chloride. In addition, an interesting observation that FeCl 3 promoted reaction was accelerated by the addition of imidazolium salt was made. All the results suggest that BTF is a tolerable solvent for free radical reaction with TTMSS and electron-transfer reactions using TBPA as well as FeCl 3.

Safe, facile radical-based reduction and hydrosilylation reactions in a microreactor using tris(trimethylsilyl)silane

A highly efficient system for tris(trimethylsilyl)silane (TTMSS) mediated deoxygenation, dehalogenation and hydrosilylation reactions is described in a microstructured device; this convenient platform enables the scale up of radical-based processes.

A tandem radical cyclization approach to 3-(2-oxopyrrolidin-3-yl)indolin-2-ones, potential intermediates toward complex indole-heterocycles

A series of substituted 3-(2-oxopyrrolidin-3-yl)indolin-2-one derivatives have been synthesized by tris(trimethylsilyl)silane (TTMSS) induced tandem radical cyclization as key step.

Tris(trimethylsilyl)silane (TTMSS)-Derived Radical Reactivity toward Alkenes: A Combined Quantum Mechanical and Laser Flash Photolysis Study

The reactivity of the tris(trimethylsilyl)silane (TTMSS)-derived radical is studied through an approach combining laser flash photolysis and quantum mechanical calculations. The results obtained for TTMSS are compared both to a classical silyl radical derived from triethylsilane and to a previously studied carbon-centered structure. Different worthwhile results are obtained: (i) the addition and hydrogen abstraction rate constants are directly measured, (ii) the high reactivity and the low selectivity of TTMSS toward the addition to alkenes are perfectly explained by antagonist polar and enthalpy effects, (iii) efficient hydrogen abstraction reactions from antioxidants such as vitamin E are observed, and (iv) TTMSS is seen to also act as an efficient initiator for the polymerization of an acrylate monomer.

Tris(trimethylsilyl)silane (TTMSS)

Tris(trimethylsilyl)silane (TTMSS) has been used in many transformations, especially in radical chain reactions. Chatgilialoglu et al. demonstrated that this reagent can be a valuable substitute for tin reagents commonly used in radical processes. [1] The Si-H bond dissociation ­energy in TTMSS of 79 kcal·mol-1 is very similar to the Sn-H bond dissociation energy of 74 kcal·mol-1 in Bu3SnH. [2] The ease of purification and the low toxicity of TTMSS make it an attractive alternative to tin as a ­reducing agent. Interestingly, there are also reports ­demonstrating that the behavior of TTMSS can be very different from that of tin hydrides. [3]

Pyridinium N-2′-pyridylaminide: synthesis of 3-aryl-2-aminopyridines through an intramolecular radical process

Tris(trimethylsilyl)silane (TTMSS) and azobisisobutironitrile (AIBN) promote the intramolecular heteroarylation of arenesulfonamides with pyridyl radicals under thermal conditions. The arenesulfonamides are easily prepared from pyridinium N-2′-pyridylaminide. The heteroarylation process involves pyridyl radical cyclization and ipso substitution.

Synthesis of carbo- and heterobiaryls by intermolecular radical addition of aryl bromides onto aromatic solvents

Tris(trimethylsilyl)silane (TTMSS) and azabisisobutyronitrile (AIBN) promoted the intermolecular arylation of aryl and heteroaryl bromides onto aromatic solvents under thermal conditions via a radical pathway.

Preparation of various C-2 branched carbohydrates using intramolecular radical reactions

A new and efficient method for the facile synthesis of C-2 branched carbohydrates has been developed using an intramolecular radical cyclization–fragmentation reaction. The desired C-2 branched glucopyranosides were isolated in 40–84% yield. Additionally, an unexpected furanoside was obtained from a tributyltin iodide-promoted rearrangement of the radical intermediate. The C-2 formyl glycal was also isolated in good yield using tris(trimethylsilyl)silane (TTMSS) as the reducing agent. This method was extended to synthesize a β C-2 branched glucopyranoside, a C-2 branched galactoside and a C-2 cyano glucopyranoside.

ChemInform Abstract: Unusual Radical ipso-Substitution Reaction of an Aromatic Methoxy Group Induced by Tris(trimethylsilyl)silane-AIBN or SmI2.

While conformationally favourable thiocarbamates bearing an aromatic methoxy group undergo intramolecular ipso-substitution of the methoxy group by treatment with tris(trimethylsilyl)silane (TTMSS) and AIBN, either conformationally flexible or favourable ketones easily cyclise into a five- or six-membered rings by treatment with SmI2.

Synthesis of biaryls via intermolecular radical addition of heteroaryl and aryl bromides onto arenes

Tris(trimethylsilyl)silane (TTMSS) and azobisisobutironitrile (AIBN) promoted the easy intermolecular arylation of aryl and heteroaryl bromides under thermal conditions via a radical pathway.

Photolysis of tris(trimethylsilyl)silane: trapping of sisyl radicals

The photolysis of tris(trimethylsilyl)silane (TTMSS) was studied in the absence and in the presence of added trapping agents such as alkenes and alcohols. It was found that, unlike the case with pyrolysis, silyl radicals rather than silylenes are produced. They may be efficiently trapped with alkenes, to give the hydrosilylation products, but not with alcohols. The major product from the photolysis of TTMSS in the absence of added trapping agent (or with alcohols as trapping agents) was tetrakis(trimethylsilyl)silane. Possible mechanisms to account for the photoproducts are presented.Key words: hydrosilane, photolysis, silylenes, silyl radical, sisyl hydride.

ChemInform Abstract: A Convenient Synthesis of 2′-Deoxy-2-fluoroadenosine; a Potential Prodrug for Suicide Gene Therapy.

A convenient synthesis of 2'-deoxy-2-fluoro-adenosine (1) is described. Deaminative fluorination of 2-aminoadenosine (2) followed by silylation of the 3', 5'-hydroxyl groups gave the corresponding 2-fluoroadenosine derivative 4 in good yield. Thiocarbonylation of 4 to thiocarbonylimidazolyl derivative 5a followed by treatment with an excess of tris(trimethylsilyl)silane (TTMSS) and tert-butyl peroxide in toluene at 80 degrees C was found to affect an efficient deoxygenation to the corresponding 2'-deoxy derivative 6. Desilylation of 6 by Et4NF in CH3CN afforded 1 in high yield.