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The reaction of N-trimethylsilyl derivatives of amides and imides with alkyl sulfonates on heating affords the corresponding N-alkyl derivatives and trimethylsilyl sulfonates.

The electrolyte additives tris(trimethylsilyl)phosphite (TMPSi) and tris(trimethylsilyl)phosphate (TMSPa) have shown their potential to improve lifetime and decrease impedance build-up in lithium i...

A tantalum-catalyzed solvent-free approach for the construction of amide bonds with 1-(trimethylsilyl)imidazole is developed, and the mild reaction conditions are applicable to a wide variety of electrophilic amino acid homologues. This approach delivers a new class of peptides in high yields without any epimerization.

C24H66Li6Si6, triclinic, P1̄ (no. 2), a = 12.2492(9) Å, b = 12.4617(9) Å, c = 14.3841(11) Å, α = 74.189(6), β = 74.543(7), γ = 85.970(6), V = 2036.2(3) Å3, Z = 2, R gt(F) = 0.0465, wR ref(F 2) = 0.0802, T = 173(2) K.

Reactions of dichlorodimethylsilane with 2,3,4,5-tetrafluorophthalic acid bis(trimethylsilyl) ether (1:1, 20°C, 24 h) without a solvent and dichloro(chloromethyl)methylsilane and dichloro(methyl)phenylsilane with bis(trimethylsilyl) ester of ortho-phthalic acid (1:1, 20°C, 168–264 h) in hexane lead to the formation of previously unknown 14-membered cyclic organosilicon esters of ortho-phthalic acids (silacyclophanones) in 36–85% yields. Molecular structures of 14-membered cyclic ethers 4,10-dimethyl-4,10-diphenyl-3,5,9,11-tetraoxo-4,10-disyla-1,7(1,2)-dibenzacyclododecaphane-2,6,8,12-tetraone, 4,4,10,10-tetramethyl-3,5,9,11-tetraoxo-4,10-disila-1,7(1,2)-di-(tetrafluorobenza)cyclododecaphane-2,6,8,12-tetraone, along with bis(trimethylsilyl) esters of 2,3,4,5-tetrafluorophthalic and orthophthalic acids, were studied by X-ray structural analysis.

Herein, the deprotonative functionalization of pyridine derivatives with aldehydes under ambient conditions has been demonstrated using an amide base generated in situ from a catalytic amount of CsF and a stoichiometric amount of tris(trimethylsilyl)amine (N(TMS)3). Pyridine substrates bearing two electron-withdrawing substituents (i.e., fluoro, chloro, bromo, and trifluoromethyl moieties) at the 3- and 5-positions efficiently react at the 4-position with various aldehydes including arylaldehydes, pivalaldehyde, and cyclohexanecarboxaldehyde.

The electroreductive coupling of 1-alkoxycarbonyl-4-quinolones with benzophenones in the presence of trimethylsilyl chloride gave adducts reacted at the 2-position of 4-quinolones as trimethylsilyl ethers. The adducts were transformed to 2-(diarylhydroxymethyl)-4-quinolones. The electroreduction of 1,3-diethoxycarbonyl-4-quinolones and polyhalogenated 3-alkoxycarbonyl-1-alkyl-4-quinolones with benzophenones also gave adducts reacted at the 2-position of 4-quinolones. On the contrary, the electroreductive coupling of 1,3-diethooxycarbonyl-8-methoxy-4-quinolones occurred at the 4-position of 4-quinolones to give 4-substituted quinolines.

A novel method for the N−N bond cleavage of trimethylsilyl diazomethane is reported for the synthesis of terminal nitride complexes. The lithium salt of trimethylsilyl diazomethane was used to generate a rare terminal nitrilimine transition metal complex with partially occupied d‐orbitals. This iron complex 2 was characterized by CHN combustion analysis, 1H and 13C NMR spectroscopic analysis, single‐crystal X‐ray crystallography, SQUID magnetometry, 57Fe Mössbauer spectroscopy, and computational analysis. The combined results suggest a high‐spin d 6 (S=2) electronic configuration and an allenic structure of the nitrilimine ligand. Reduction of 2 results in release of the nitrilimine ligand and formation of the iron(I) complex 3, which was characterized by CHN combustion analysis, 1H NMR spectroscopic analysis, and single‐crystal X‐ray crystallography. Treatment of 2 with fluoride salts quantitatively yields the diamagnetic FeIV nitride complex 4, with concomitant formation of cyanide and trimethylsilyl fluoride through N−N bond cleavage., Chain reaction: A fluoride salt cleaves the N–N bond of an iron trimethylsilyl nitrilimine complex and generates the terminal nitride, fluorotrimethylsilane, and cyanide. The complementary reactivity of nitrilimine and azido ligands provides a new approach for the synthesis of metal terminal nitrido complexes.

A novel synthetically important reaction has been developed for the quick, convenient, and high-yield preparation of trimethylsilyl esters of phosphorus(III) acids, synthetically valuable Michaelis–Arbuzov reaction precursors. Commercially and synthetically available initial compounds used are derivatives of propan-2-ol phosphorylated in the second position capable of long-term storage and available silylating reagents: hexamethyldisilazane, bis(trimethylsilyl)acetamide, and diethyl(trimethylsilyl)amine. Also, a stepwise reaction scheme of the starting compounds with silylating reagents has been proposed.

Extending the chemistry of disilene fluoride adducts studied earlier by us, we investigated the formation of 1,1-bis(trimethylsilyl)fluorodiphenylsilylsilanide, which was prepared by reaction of (Me3Si)3SiSiPh2F with KOtBu. The formed FPh2SiSi(Me3Si)2K displays distinctively different structural and spectroscopic features compared to the earlier reported F(Me3Si)2SiSi(SiMe3)2K. While the latter eliminates metal fluoride upon reaction with MgBr2, the respective magnesium silanide is formed from FPh2SiSi(Me3Si)2K. Reaction of (Me3Si)3SiSiPh2Cl with KOtBu proceeded similarly, but the formed ClPh2SiSi(Me3Si)2K easily undergoes potassium chloride elimination to the disilene Ph2Si═Si(SiMe3)2. Compared to F(Me3Si)2SiSi(SiMe3)2K, which can be regarded as a disilene fluoride adduct, structural, spectroscopic, and reactivity properties of FPh2SiSi(Me3Si)2K distinguish it as a β-fluorodisilanide.

The reactions of propargylamines 1,4 -bis(3-phenylprop-2-yn-1-yl)piperazine ( 1 ) and 1,4 -bis(3-(trimethylsilyl)prop-2-yn-1-yl)piperazine ( 2 ) with PdCl 2 and CuI is described. 1,4 -Bis(3-phenylprop-2-yn-1-yl)piperazine reacts with one equivalent of PdCl 2 to afford κ 2 - N,N -coordinated complexes [PdCl 2 {Me 3 SiC ≡CCH 2 NC 4 H 8 NCH 2 C≡CSiMe 3 -κ 2 - N,N ] ( 3 ) and [PdCl 2 {Me 3 SiC ≡CCH 2 NC 4 H 8 NCH 2 C≡CSiMe 3 }-κ 2 - N,N ] ( 4 ). The reactions of 1 and 2 with two equivalents of PdCl 2 yielded rare chloropalladated tetranuclear complexes [Pd 4 ( μ -Cl 4 )Cl 4 (PhC≡CCH 2 NC 4 H 8 NCH 2 C≡CPh) 2 ] ( 5 ) and [Pd 4 ( μ -Cl 4 )Cl 4 (Me 3 SiC ≡NC 4 H 8 NCH 2 C ≡C SiMe 3 ) 2 ] ( 6 ), respectively, resulting from the trans nucleophilic addition of chloride ion onto the electrophilic C ≡C bond. The reactions of 1 and 2 with two equivalents of CuI produced 2-D coordination polymers [{Cu 2 ( μ -I)} 2 (PhC≡C–CH 2 NC 4 H 8 NCH 2 C≡CPh)] n ( 7 ) and [{Cu 2 ( μ -I)} 2 (Me 3 SiC ≡CCH 2 NC 4 H 8 NCH 2 C≡CSiMe 3 )] n ( 8 ), respectively. Similar reactions in 1:1 M ratios produced dimeric complexes [Cu 2 ( μ -I) 2 (PhC≡CCH 2 NC 4 H 8 NCH 2 C≡CPh) 2 ] ( 9 ) and [Cu 2 ( μ -I) 2 (Me 3 SiC ≡CCH 2 NC 4 H 8 NCH 2 C≡CSiMe 3 ) 2 ] ( 10 ), respectively. The structures of compounds 3 , 5 and 7 have been established by single crystal X-ray analysis.

Two alternative synthetic approaches to new silicon-containing oligo(arylenevinylenes), 1,4-bis-{(E)-2-[4-(trimethylsilyl)phenyl]ethenyl}benzene and 9,10-bis{(E)-2-[4-(trimethylsilyl)phenyl]ethenyl}anthracene via Heck reactions of trimethyl(4-vinylphenyl)silane with the corresponding dibromoarenes and of (4-bromophenyl)trimethylsilane with the corresponding divinylarenes were studied. The reaction of 9,10-divinylanthracene with (4-bromophenyl)trimethylsilane was found to be accompanied by elimination of one trimethylsilyl group.

A novel and easily accessible MN(SiMe3)2 (M = Li or Na)/Cs2CO3 co-catalyzed benzylation of in situ generated N-(trimethylsilyl) aldimines with toluene derivatives has been successfully developed. T...

Twofold unsymmetrical C-Si bond bifunctionalization of 2,6-di(trimethylsilyl) benzyl alcohols has been achieved in one pot via sequential [1,4]-Csp2 to O-silyl migration. The hydroxyl group functions as an "on-off-on" switch to control two successive silyl migrations, and 4,7-dimethyl-o-phenanthroline ligand favors cleavage of the endocyclic C-Si bond. Diverse Csp3/Csp3 or Csp2/Csp3 electrophiles can be installed at the 2- and 6-positions. This approach was used to chemoselectively functionalize the three C-Si bonds of 2,4,6-tri(trimethylsilyl) benzyl alcohol, transforming it into isochroman derivatives. The approach even works as a five-component reaction to construct complex symmetric structures.

A contrapositionally substituted derivative of cyclohexa-meta-phenylene ([6]CMP) was synthesized by an intramolecular Yamamoto coupling reaction of an appropriate terphenyl unit containing a trimethylsilyl substituent. Iododesilylation of the trimethylsilyl groups of the product with iodine monochloride was used to incorporate iodo groups, an important functionality for metal-catalyzed coupling reactions. The iodo groups were also converted into a (pinacolato)boryl groups, another important functionality for coupling reactions. The diborylated [6]CMP is expected to be a versatile potential comonomer and a precursor for the synthesis of CMP-based materials. The synthetic route to the disubstituted [6]CMP included lithiation, Pd-catalyzed borylation, Suzuki coupling, and Yamamoto coupling. The structure of the product was established by NMR spectroscopy and mass spectrometry.

Poly(1-trimethylsilyl-1-propyne) modified with quaternary ammonium salts is synthesized. The introduction of salts into the polymer structure is carried out using a two-step method consisting in the bromination of the starting polymer followed by the addition of tertiary alkylamines—trimethylamine and triethylamine. The presence of ammonium salts is confirmed by the data of organometallic analysis and IR spectroscopy. X-ray diffraction analysis is used to study the supramolecular structure of the materials obtained. The TGA data indicate their high thermal and thermo-oxidative stability. The permeability, solubility, and diffusion coefficients of the poly(1-trimethylsilyl-1-propyne) samples containing trimethylamine and triethylamine salts for individual CO2, N2, and CH4 gases are determined. An increased ideal selectivity for the separation of gas pairs CO2/N2 and CO2/CH4 in modified poly(1-trimethylsilyl-1-propyne) is achieved owing to the increased selectivity of the dissolution of CO2 in quaternary ammonium salts.

Commercially viable synthesis of InP nanocrystals (NCs) involves highly pyrophoric phosphorus (P) precursor, tris(trimethylsilyl) phosphine (TMS3P). Finding a cheap and safe alternative would be the holy grail. We report the synthesis of InP NCs using triphenyl phosphite, an inexpensive and relatively safe phosphorous source. By reacting indium chloride and triphenyl phosphite, we obtained large-sized and black-colored InP NCs, yet without any distinct feature that shows quantum confinement effect. Addition of ZnCl2 resulted in InP NCs with controlled size, which was manifested in the shift of 1S peak in absorption spectra. By coating ZnS shell on InP NCs, we achieved photoluminescence with some extent of trap emission, showing maximum total quantum yield (QY) of 23% (8% of band-edge emission QY). We used 31P nuclear magnetic resonance (NMR), diffusion-ordered spectroscopy (DOSY), and mass spectrometry (MS) to assign intermediates and following mechanisms of the InP synthesis using triphenyl phosphite. The development of this safe and cost-effective P precursor opens broader opportunity space for large-scale production of InP NC.

In this work, the polymerization of 1-trimethylsilyl-1-propyne [TMSP] using catalytic systems based on pentabromide Nb(V) and Ta(V) with organometallic cocatalysts Ph3Bi, Ph4Sn, Bu4Sn, Ph3SiH, and Et3SiH was investigated. The use of NbBr5-based catalytic systems has strongly marked cis-stereospecificity and gives highly cis-enriched poly(1-trimethylsilyl-1-propyne) [PTMSP] (content of cis-units above 70%), whereas the use of TaBr5-based catalytic systems leads to the formation of PTMSP with mixed cis-/trans-composition (content of cis-units from 50 to 65%).With increasing cis-content, solvent resistance of PTMSP increases significantly. PTMSP with a content of cis-units above 70% obtained on NbBr5-containing systems in cyclohexane acquires resistance to aliphatic and aromatic hydrocarbons, and cis-regular PTMSP obtained on NbBr5-based systems in toluene is totally insoluble in any of the organic solvents. The results of wide-angle X-ray diffraction indicate an increase in the packing density of the polymer during the transition from a mixed configuration to a cis-regular one. Durable PTMSP film membranes exhibit ultra-high permeability coefficients for individual gases (e.g., $${{P}_{{{{{\text{O}}}_{{\text{2}}}}}}}$$ = 8500–11000 barrer, $${{\alpha }_{{{{{\text{O}}}_{{\text{2}}}}{\text{/}}{{{\text{N}}}_{{\text{2}}}}}}}$$ = 1.5–1.9). According to the low-temperature Ar sorption, PTMSP synthesized with NbBr5- and TaBr5-based catalytic systems has high BET surface areas in the range of 870–1050 m2/g, high intrinsic microporosity, and higher gas permeability coefficients of PTMSP correlate with BET surface area growth.

Thiocyanation of aromatic compounds has been investigated using the combination of 1-chloro-1,2-benziodoxol-3-(1H)-one (1) and (trimethylsilyl)isothiocyanate (TMSNCS). The reaction with electron rich aromatic compounds proceeded smoothly to provide the thiocyanated products in high yield, while electron deficient heteroaromatic compounds were not suitable for this reaction. In these reactions, the regioselectivity was generally high. Transformations of the products were also investigated to demonstrate the utility of the reaction. Based on NMR experiments, we propose that thiocyanogen chloride is generated in situ as an active species.

The C O bonds are kinetically inert in cross-coupling reactions compared to those of carbon–halogen bonds. Thus, developing methodologies for the activation of C O bonds in cross-coupling reactions remains a major challenge. We disclose an unprecedented nickel mediated cross-coupling of carbamates with silylmagnesium reagents that does not require the expensive silylboranes. Silylmagnesium reagents were prepared from either silyllithium or silyl iodides. This methodology is distinguished by the synthesis of trimethylsilyl coupled product and its synthetic applications. Kinetic studies and radical clock experiments revealed the rate-limiting C O bond cleavage, half order with respect to the catalyst and a non-radical transition state.

Potassium hexafluorophosphate and tris (trimethylsilyl) phosphite are applied as electrolyte additives to enhance electrochemical performance of an anode-free lithium metal battery (AFLMB) based on a Cu‖NMC cell configuration. The synergistic effect of the dual additives has been investigated using a commercial carbonate electrolyte (1 M LiPF6-EC/DEC (1:1 vol%)). Herein, we report that an electrolyte with dual additive of 2 wt% KPF6 - 2 vol% TMSP significantly improves the charge/discharge capacity, average coulombic efficiency and retention capacity of a Cu‖NMC cell configuration. An AFLMB cell with 2 wt% KPF6 - 2 vol% TMSP additives retained 48% of its initial capacity at the 20th cycle, while the reference cell with the commercial electrolyte in the absence of additives reached only 14%. The enhanced performance using the prepared electrolyte is attributed to the self-healing electrostatic shielding (SHES) effect of KPF6 to prevent dendrite growth and the removal of hydrofluoric acid (HF) produced from the commercial LiPF6 carbonate electrolytes by the reaction of phosphorus pentafluoride (PF5) with water using TMSP. This study provides a broader vision in developing functional electrolyte additives for an anode-free lithium metal battery.

The melting point and enthalpy of fusion are refined for p-quaterphenyl (4P) and measured for the first time for its derivative with two terminal trimethylsilyl substituents (TMS-4P-TMS) by DSC method. The optical absorption spectra of 4P and TMS-4P-TMS solutions in toluene are measured at 25°C. Analysis of the absorption spectra shows the range within which aggregated solutions of the investigated substances exist. The shape of the absorption spectra of concentrated TMS-4P-TMS solutions indicates the J-aggregation of molecules occurs. It is found that the solubility of the TMS-4P-TMS derivative in toluene at room temperature is almost six times higher than that of p-quaterphenyl. Large single-crystal films and plates of the investigated compounds (up to 8 mm in size for 4P and up to 25 mm in size for TMS-4P-TMS) are obtained by growing them from solutions. Data on crystal growth of TMS-4P-TMS are reported for the first time.

Chromatographic determination of the thermodynamic parameters of sorption for light hydrocarbons retention on a stationary phase based on poly [trimethylsilyl (propyn-1)] (PTMSP) was performed and the effect of column preheating at temperatures up to 260°C on the retention of analytes was investigated. It was shown that heating the column to 130°C does not affect the retention of the analytes. At temperatures above 130°C, the gradual decrease of the retention of analytes on PTMSP stationary phase is observed. The process is non-selective and proceeds at the same extent for all the studied hydrocarbons, regardless of the size and geometry of the molecule. Values of enthalpy and entropy of sorption of light hydrocarbons are determined for the original column and after its aging at 200°C. The enthalpy of sorption of the analytes at the PTMSP phase is practically independent on the heating temperature of the PTMSP phase, whereas the loss of entropy increases after heating. The increase of the entropy factor after the heating of the PTMSP stationary phase is associated with its aging and is confirmed by the construction of compensation functions for treated and untreated columns.

Tris[N,N-bis(trimethylsilyl)amido]lanthanum (LaNTMS) is an efficient, highly active, and selective homogeneous catalyst for ester reduction with pinacolborane (HBpin). Alkyl and aryl esters are cle...

Benzyne precursors are rapidly becoming well-used building-blocks for organic materials.1 Our synthesis of conjugated oligoacene precursors by benzyne Diels-Alder reactions created a need for a rel...

Oligo(spiroketal)s (OSKs) were synthesized from myo‐inositol, a naturally occurring cyclic compound bearing six hydroxyl groups. The successful synthesis of OSKs was achieved using silyl ethers 2 derived from 1,4‐di‐O‐alkylated myo‐inositol 1 as monomers, which underwent polycondensation with 1,4‐cyclohexanedione (CHD) at 0 °C in the presence of trimethylsilyl triflate as a catalyst. Because of the irreversible nature of the condensation reaction of silyl ethers with ketones, the resulting OSKs 7 had higher molecular weights than previously reported OSKs that were obtained by polycondensation of tetraols 1 with CHD, where backward hydrolysis of the ketal functions occurred. In addition, another series of OSKs, 8, were synthesized using silyl ethers 3 derived from 2,5‐di‐O‐alkylated myo‐inositol 6, which are more symmetric monomers than silyl ethers 2. Silyl ethers 3 underwent efficient polycondensation with CHD, whereas tetraol 6 did not, demonstrating that the derivation of such tetraols into the corresponding silyl ethers is a powerful strategy to access OSKs. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2407–2414

Active species for synthetic and catalytic applications are formed from well defined complexes or mixtures of compounds. For group 4 metallocenes, three pathways for the formation of the reactive complex fragment [Cp′2M] are known: (i) reductive mixtures and well defined complexes which are able to form the metallocene fragments either by (ii) addition or (iii) substitution reactions. In this account for each of theses systems (i)–(iii) a prominent example will be discussed in detail, (i) the Negishi reagent Cp2ZrCl2/n‐BuLi, (ii) bis(η5 : η1‐pentafulvene) complexes and (iii) metallocene bis(trimethylsilyl)acetylene complexes, to show the advantages and the disadvantages for each of these methods for synthetic applications. This account summarizes some main advantages of group 4 metallocene bis(trimethylsilyl)acetylene complexes as metallocene generating agents over other synthetically used systems. For each of the special purposes, all described systems have advantages as well as disadvantages. The aim of this overview is to help synthetic chemists in selecting the most effective system on the basis of [Cp′2M] (M=Ti, Zr) for synthetic or catalytic puposes.

C28H78Si10, monoclinic, Pn (no. 7), a = 21.413(4) Å, b = 9.8568(17) Å, c = 22.074(4) Å, β = 93.426(4)°, V = 4650.6(14) Å3, Z = 4, R gt(F) = 0.0613, wR ref(F 2) = 0.1750, T = 296(2) K.

Chiral cyclopentadienyl (Cpx) group 9 metal complexes have become versatile catalysts for a variety of efficient enantioselective C–H functionalizations. Atropchiral binaphthyl-derived Cpx ligands having tuning options at the 3,3′-positions present a robust choice of catalyst, giving high enantioselectivities and good reactivities. Herein, we report streamlined syntheses of binaphthyl backbone Cpx ligands that feature new substituents at the 3,3′-positions: namely, trimethylsilyl, I, and Br. We introduce as well Cpx ligands with a new atropchiral MeO-biphenyl backbone. All ligands are smoothly complexed with rhodium(I) salts. The CpxRhI complexes obtained were systematically mapped by X-ray crystal analysis in order to collect steric parameters that might guide a rational selection of the chiral Cpx ligand for enantioselective reactions. The catalytic performances of the complexes were evaluated by two RhIII-catalyzed C–H functionalizations as benchmark transformations. In both cases, a simpler to access ...

The mechanisms and regioselectivities of Fe(0)-catalyzed alkylation of aromatic compounds with alkenes were explored by DFT calculations. Our calculations show that these systems tend to undergo anti-Markovnikov addition. The influence of steric effects on the reaction mechanism has been investigated. The results indicate that the reaction is more likely to provide the linear product with dissociation of the 1PMe3 ligand. The reductive elimination is the rate-determining step of the whole process, such that the electrostatic interactions of the reaction site and the steric hindrance of the trimethylsilyl groups are favorable for the anti-Markovnikov rather than the Markovnikov addition pathway. Our calculations provide insights into the regioselective origin of the alkylation of aromatic compounds mediated by Fe(PMe3)4.

Reduction of ansa-titanocene dichlorides [X(η5-C5H4)2TiCl2] (X = SiMe2 (1) and CMe2 (2)) in tetrahydrofuran (THF) by preactivated magnesium in the presence of bis(trimethylsilyl)acetylene (BTMSA) yielded complexes [X(η5-C5H4)2Ti(η2-BTMSA)] (X = SiMe2 (3) and CMe2 (4)). The prolonged action of excess magnesium and BTMSA resulted in the formation of ansa-titanium-magnesium complexes [μ-X{(η5-C5H4)Ti(η2-SiMe3C≡CSiMe3)2}{(η5-C5H4)Mg(THF)}] (X = SiMe2 (5) and CMe2 (6)), which had their metals bounded via the ansa-ligand and ionic bonding between magnesium and the BTMSA ligands. Compounds 5 and 6 easily isomerized to 5a and 6a through rotation of their {(C5H4)Mg(THF)} moiety around the ansa- X–C bond. This rotation canceled the interaction of magnesium with the BTMSA ligands, which resulted in a large high-field shift of acetylenic carbon resonances. The geometry of both structures optimized by Density Functional Theory (DFT) computations together with the good correlation of computed magnetic shieldings and experimental 13C NMR shifts of 5 and its isomer 5a approved the above isomerization. The simultaneous ionic bonding of Mg2+ to the cyclopentadienyl ligand, which is η5-coordinated to the {Ti(η2-BTMSA)2} moiety in 5a got also confirmed by computational results. Reduction by magnesium was used to obtain Ti(III) dimers of ansa-titanocene acetylides [{X(η5-C5H4)2Ti (μ-η1:η2-C≡CSiMe3)}2] (X = SiMe2 (7) and X = CMe2 (8)) via redox splitting of 1,4-bis(trimethylsilyl)buta-1,3-diyne (BSD) by transient Ti(II) titanocene. The thermally stable Ti(II) compounds 3 and 4 were also shown to react with BSD yielding respectively 7 and 8. The reduction of 1 and 2 with magnesium in THF afforded Ti(III) monochloride dimers [{ansa-X(η5-C5H4)2Ti(μ-Cl)}2] (X = SiMe2 (10); CMe2 (11)), which in contrast to the non-ansa dimer [(η5-C5H5)2Ti(μ-Cl)}2] were silent in toluene glass EPR spectra. No evidence of obtaining quadruply bridged dititanium complexes capped with the ansa-ligands was encountered among crystal structures of 7–11, even though the total energy of optimized molecules 7 and 10 and their capped congeners differed by more than 45 kJ/mol, favouring the capped isomers in both cases.

This work is devoted to the chemical modification of the polymers of 1,2-disubstituted acetylenes for the creation of gas-separation membranes possessing enhanced stability to aliphatic hydrocarbons and CO2 selectivity. The feasibility of obtaining polyacetylenes containing chlorine atoms in the side substituents of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) by radical chlorination with N-chlorosuccinimide has been shown. The reaction has been carried out under mild conditions to minimize the possibility of polymer degradation and other side reactions. The obtained polymers exhibit good mechanical and film-forming properties as well as high thermal stability. Chlorinated PTMSP possesses enhanced stability to alicyclic and aliphatic C5–C12 hydrocarbons. It has been shown that in the case of introduction of chlorine into the structure of PTMSP and PMP, the CO2/N2 and CO2/CH4 selectivities increase, with the high level of permeability being retained.

A robust and efficient synthesis of triisopropylsilyl (TIPS)-protected γ-substituted enoldiazoacetates with excellent Z stereocontrol by using lithium bis(trimethylsilyl)azanide (LiHMDS) as a base and TIPSOTf as a silyl transfer reagent is reported. Despite their increased size compared to previously tert-butyldimethylsilyl (TBS)-protected γ-unsubstituted enoldiazoacetates, a high product yield with exceptional stereocontrol has been achieved in copper-catalyzed [3+3] cycloaddition reaction with nitrones by using a chiral indeno bisoxazoline ligand.

Cesium bismuth halides (Cs-Bi-X) have recently been the subject of considerable attention as possible less-toxic alternatives to lead halide perovskites for luminescence and photovoltaics applications, but the full range of synthetically accessible Cs-Bi-X compositions has not been thoroughly explored, and some inconsistent results have appeared in the literature. Here, we have used a combination of hot-injection synthesis and post-synthetic anion exchange to prepare Cs-Bi-X nanocrystals with many structures and compositions, including several that have not previously been characterized. The structural and optical properties of Cs3BiX6 (X = Cl, Br, I) nanocrystals and Cs3Bi2X9 (X = Cl, Br, I) nanoplatelets are reported, and interconversion of these structures between different halide compositions is demonstrated through anion exchange using trimethylsilyl halides. Notably, we find that anion exchange can be used to access structural polymorphs not readily prepared through direct synthesis. In particular, ...

We have studied the effect of N-substitution on the course of the reaction of imidazolium triflate. The reaction of N-heterocyclic carbene with N-tBu-substituted pyrrolinium triflate afforded 2-(pyrrolidin-2-yl)-imidazolium triflate, 3R. Treatment of 3R with potassium bis(trimethylsilyl)amide (KHMDS) leads to either the dealkylation product 4 or the deprotonation product, triazaalkene 5, depending on the N-substitution at the imidazolium moiety. Density functional studies using the B3LYP/TZVP setup have been employed to explore various pathways for the dealkylation reaction and the calculated energies support the dealkylation by a large energy margin compared to the deprotonatation process. Theoretical calculations revealed that dealkylation reaction is thermodynamically more favorable than deprotonation. The triazaalkene 5 could be oxidized by AgOTf to the corresponding radical cation 6 and dication 7 in-situ. While 6 and 7 could not be isolated, the formation of the former is inferred by electron paramagnetic resonance spectroscopy and its abstraction of a H-atom to afford 3Me. Similarly, the formation of the dication 7 is inferred by its ready elimination of isobutylene affording 8.

{(1S,4R,5R)-5-[tert-Butyl(dimethyl)silyloxymethyl]-4-hydroxycyclopent-2-en-1-yl}acetaldehyde, the key building block in a possible approach to 15-deoxy-Δ12,14-prostaglandin J2, has been synthesized starting from (3aR,6R,6aS)-6-(trimethylsilyl)-3,3a,6,6a-tetrahydro-1H-cyclopenta[c]furan-1-one.

1,4-Bis(trimethylsilyl)-1,4-diaza-2,5-cyclohexadiene, 1, was tested as a reagent for the reductive silylation of various unsaturated functionalities, including N-heterocycles, quinones, and other redox-active moieties in addition to deoxygenation of main group oxides. Whereas most reactions tested are thermodynamically favorable, based on DFT calculations, a few do not occur, perhaps giving limited insight on the mechanism of this very attractive reductive process. Of note, reductive silylation reactions show a strong solvent dependence where a polar solvent facilitates conversions.

A new Ni(II)-based metal–organic framework with the chemical formula of (Me2NH2)[Ni3(L)2(μ3-OH)(H2O)]·2DMF (1) have been designed and synthesized by the reaction of 3-phenylpyridine polycarboxylic (H3L) ligands and Ni(NO3)2·6H2O in a mixed solvent of DMF and water under the solvothermal conditions. The resulting solvent-free 1a was found to be catalytically active for the cyanosilylation reaction of aromatic aldehydes with nitro substituent in varying positions in the presence of trimethylsilyl cyanide to afford cyanohydrin trimethylsilyl ethers in a shape and size selective manner. The as-prepared 1 did not exhibit catalytic activities for the same reaction. Based on the experimental results, a possible catalytic mechanism has also been proposed. We next examined the cell viability with CCK-8 assay and the cell proliferation with plate colony formation assay. Both experiments suggested the inhibitory effect of compound 1a on human promyelocytic leukemia cancer HL-60 cells. For the mechanism exploration, the ROS content in HL-60 cancer cells was measured with detection kit, results also indicated the compound 1a increased the level of ROS in HL-60 cells, which may the reason of the compound’s anti-cancer activity.

Attracted by the numerous regulatory functions of double-helical biopolymers such as DNA, many researchers have synthesized various double-helical systems. A recently synthesized double-stranded helical oligomer covalently bridged by rotary boronate esters (BBDD) was shown to undergo helix-inversion that might serve as platform to design rotor systems. However, the detailed helix-inversion mechanism could not be investigated experimentally. Direct molecular dynamics simulations based on density-functional tight-binding energies and gradients computed on-the-fly reveal that disentanglement to the unraveled form and following exchange of the twisted terminal trimethylsilyl (TMS) groups are prerequisites for the observed helix-inversion. The potential of mean force confirms that the originally assumed "concurrent" rotation of the boronate esters and the helix-inversion involves shorter time scale "step-wise" processes, triggered by the disentanglement and exchange of the TMS groups. These results indicate that inversion dynamics of double-helical molecules such as BBDD may be controllable by chemical fine-tuning of the terminal groups. © 2019 Wiley Periodicals, Inc.

The efficient and practical nucleophilic cyanation and trifluoromethylation with appropriate trimethylsilyl nucleophiles were developed. Catalytic amounts of cheap and nontoxic Cs2CO3 were used to ...

The synthesis of two bifunctional compounds bearing a terminal hydroxy-bisphosphonic function (HBP) was achieved following a linear and a convergent strategy. In the linear approach, the free hydroxy-bisphosphonic function was introduced in the last step of the synthesis, under neutral conditions using an Arbuzov reaction with tris(trimethylsilyl) phosphite and a carboxylic acid precursor activated in situ with catecholborane. In the convergent approach, Huisgen type cycloaddition was studied starting from an HBP-functionalized alkyne partner to obtain the targeted bifunctional molecule. These complementary approaches allow for the preparation of complex bone-targeting molecules as potential prodrug candidates.

The reactions of t-Boc-protected secondary and primary amines with difluorocarbene generated from trimethylsilyl (fluorosulfonyl)difluoroacetate [Me3SiOC(O)CF2SO2F] (TFDA) in toluene at 110 °C results in the replacement of t-Bu by difluoromethyl in the t-Boc group. This reaction can be carried out in the presence of CH2Br and COOMe moieties in the structure of the protected amine. In the example of a t-Boc-protected amine containing a C=C double bond, replacement of the t-Bu group and/or cyclodifluoropropanation takes place. Difluoromethyl esters are shown to react with primary and secondary amines yielding the corresponding ureas.

An acyclic flexible bis(α-iminopyridine) ligand has been employed for the stabilization of chlorostannyliumylidene and a tin(II) dication. The syntheses involve the abstraction of chloride from the tin dichloride precursor using trimethylsilyl trifluoromethane sulfonate. The apically disposed tin(II) dication exhibits electrophilic behaviour and undergoes transmetallation reaction with GeCl2.dioxane resulting in stabilizing the Ge(II) dication. All the compounds have been characterized by NMR techniques and single crystal X-ray crystallography.

2,2,2-Trichloro-N-[(trimethylsilyl)methyl]acetamide and 2,2,2-trimethyl-N-[(trimethylsilyl)-methyl]acetamide were prepared by reaction of N-[(trimethylsilyl)methyl]amine with acid chlorides of the corresponding acids. The crystal structure of 2,2,2-trichloro-N-[(trimethylsilyl)methyl]acetamide was studied by X-ray analysis. Quantum chemical calculations (DFT 6-311++G**) were performed and FTIR-spectrum were obtained for study of self-association of these amides in gas phase and solutions in inert media.

Aromatic methoxymethyl (MOM) ethers behave differently from aliphatic MOM ethers upon treatment with trialkylsilyl triflate (R3SiOTf) and 2,2′-bipyridyl. The aromatic MOM ethers are first converted to silyl ethers and subsequently deprotected by hydrolysis to give the mother alcohols when the R3SiOTf used is trimethylsilyl triflate (TMSOTf). Conversely, direct conversion of aromatic MOM ethers to aromatic triethylsilyl (TES) ethers is possible when the R3SiOTf used is triethylsilyl triflate (TESOTf).

Stabilization of an amidinatosilylene with a bulky tris(trimethylsilyl)silyl substituent was realized with the preparation of PhC(NtBu)2Si{Si(SiMe3)3} (1) from PhC(NtBu)2SiHCl2 with K{Si(SiMe3)3} in more than 90% yield. The highly deshielded 29Si NMR resonance (δ = 76.91 ppm) can be attributed to the absence of a π-donating substituent. The molecular structure of 1 shows a trigonal-planar geometry around the SiII center with a SiII–SiIV bond length of 2.4339(13) A. A series of reactions of 1 with Me3NO, S, Se, and Te were performed. While siloxane derivatives (2 and 3) are obtained from reactions with Me3NO, silachalcogenones (4–6) are formed with other chalcogens. The presence of Si═E (E = S, Se, and Te) bonds in 4–6 have been confirmed by single-crystal X-ray studies. Silaoxirane (7) formation was observed when 1 was treated with acetone, demonstrating the importance of the tris(trimethylsilyl)silyl group to kinetically and thermodynamically protect the silaoxirane derivative with less bulky substituent...

As an extension of the study on the Hudrlik–Peterson reaction of trans-TMS-epoxy alcohols with lithium acetylides, four cis-TMS-epoxy alcohols possessing different alkyl substituents were subjected to the reaction with TMS-acetylide. The reaction completed in 1 h at 0 °C to afford cis-enynyl alcohols in good yields. The results indicated that cis-TMS-epoxy alcohols had higher reactivity than the trans-isomers. Anions derived from 1-heptyne and phenylacetylene participated in the reaction as well. The reaction was applied to optically active cis-TMS-epoxy alcohols, and the resulting enynyl alcohols were transformed to the synthetic intermediates of protectin D1, maresin 1, resolvin E1, and leukotriene B4.