Reaction Of Trimethyl Research Articles

Thermodynamics of transamination reactions with aminotrimethylsilanes and diaminodimethylsilanes

Abstract Transamination reactions of two different aminosilanes (trimethyl(tert-butylamino)silane and dimethyl(diamino)silane) with amines (diethylamine, pyrrolidine, tert-butylamine, iso-propylamine, and n-propylamine) are studied. For trimethyl(organoamino)silanes, the reaction of trimethyl(iso-propylamino)- or trimethyl(diethylamino)silane as aminosilanes and aniline or pyrrolidine are good starting materials to produce trimethyl(anilino)- and trimethyl(pyrrolidino)silane. The investigated equilibrium constants of the reactions of monoaminosilanes show a good correlation with quantum chemically calculated values. The reaction of two different diaminosilanes Me2Si(NR1R2)2 and Me2Si(NR3R4)2 containing different amino moieties leads to the formation of mixed diaminosilanes Me2Si(NR1R2)(NR3R4) in most cases.

Metal-Free C–H Difluoromethylation of Imidazoles with the Ruppert–Prakash Reagent

The reaction of trimethyl(trifluoromethyl)silane-tetrabutylammonium difluorotriphenylsilicate (CF3SiMe3-TBAT) with a series of imidazoles gives products of the formal difluorocarbene insertion into the C-H bond at the C-2 position (i.e., C-difluoromethylation). According to NMR spectra, the corresponding 2-(trimethylsilyl)difluoromethyl-substituted derivatives are likely formed as the intermediates in the reaction, and then, they slowly convert to 2-difluoromethyl-substituted imidazoles. Quantum chemical calculations of two plausible reaction mechanisms indicate that it proceeds through the intermediate imidazolide anion stabilized through the interaction with solvent molecules and counterions. In the first proposed mechanism, the anion reacts with difluorocarbene without an activation barrier, and then, the CF2 moiety of the adduct attacks the CF3SiMe3 molecule. After the elimination of the CF3 anion, 2-(trimethylsilyl)difluromethyl-substituted imidazole is formed. Another possible reaction pathway includes silylation of imidazolide anion at the N-3 atom, followed by the barrierless addition of difluorocarbene at the C-2 atom and then by 1,3-shift of the SiMe3 group from N-3 to the carbon atom of the CF2 moiety. Both proposed mechanisms do not include steps with high activation barriers.

Adsorption and Reaction of Trimethyl and Triethyl Phosphite on Fe3O4 by Density Functional Theory

First-principle density functional theory (DFT) calculations are used to calculate the most stable structures and heats of adsorption of trimethyl and triethyl phosphites on an Fe3O4 surface in order to understand their behavior as lubricant additives. Previous surface science studies of phosphate and phosphite esters on iron oxide surface have shown that they react by sequentially desorbing the corresponding alcohol and aldehyde in equimolar amounts. This implies that the reactions are limited by the rate of alkoxide removal, followed by a rapid reaction to form the alcohol and aldehyde. It is found that the trialkyl phosphites, dialkyl phosphite, and monoalkyl phosphite all adsorb with the phosphorus atoms bound to surface Fe3+ ions, with the alkoxy groups close to parallel to the surface. The heat of adsorption increases as the alkoxide groups are removed. The postulate that the rate-limiting step in the decomposition of the phosphate esters is the sequential removal of the alkoxide group is tested by plotting the experimental activation energy obtained from temperature-programed desorption experiments versus the corresponding heats of adsorption calculated by DFT. A linear dependence shows that the reaction obeys the so-called Evans–Polanyi relation, thereby confirming the above postulate. The slope of the plot is close to unity and thus implies that the structure of the transition state of the reaction resembles the product.

Heck Synthesis of New Organosilicon Oligo(arylenevinylenes)

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.

Oxidative sulfamidation of vinyl silanes: A route to diverse silylated N-Heterocycles

The reaction of trimethyl(vinyl)silane 1 and dimethyl(divinyl)silane 2 with various sulfonamides in the oxidative system (tert-BuOCl + NaI) has been studied and shown to be an efficient approach for the synthesis of silylated N-heterocycles. Triflamide demonstrated the reactivity principally different from that of arenesulfonamides. With silane 1, it afforded the products of iodochlorination and bis(triflamidation) (major), whereas arenesulfonamides gave N-arenesulfonylaziridines in up to 91% yield. Silane 2 with arenesulfonamides yielded the products of mono and bis(iodochlorination), mono and bis(aziridination), and 3,5-diiodo-4,4-dimethyl-1-(arylsulfonyl)-1,4-azasilinanes. By contrast, triflamide, apart from the products of halogenation and iodotriflamidation, unexpectedly gave 3-(trifluoromethylsulfonyl)-5-(triflamido)oxazolidine as the main product. The structure of most heterocyclic products is proved by X-ray analysis. The effect of the silyl group in the substrate and of the substituent in the reagent on the course of oxidative sulfamidation is discussed by comparing with all-carbon analogues.

Solvent interception, heterocyclization and desilylation upon NBS-induced sulfamidation of trimethyl(vinyl)silane.

The reaction of trimethyl(vinyl)silane with sulfonamides in the presence of N-bromosuccinimide was shown to proceed regioselectively in methylene chloride under mild conditions and led to the products of bromosulfamidation in up to 88% yield. The obtained adducts undergo base-promoted dehydrobromination to give 2-trimethylsilyl-N-sulfonyl aziridines in a close to quantitative yield. In the reaction with trifluoromethanesulfonamide in acetonitrile or tetrahydrofuran, the Ritter-type (solvent-interception) products were obtained and converted to 1-triflyl-2-methyl-5-(trimethylsilyl)-2-imidazoline or 4-triflyl-3-(trimethylsilyl)-1,4-oxazocane in almost quantitative yield.

ChemInform Abstract: One‐Pot in situ Formation and Reaction of Trimethyl(trichloromethyl)silane: Application to the Synthesis of 2,2,2‐Trichloromethylcarbinols.

2,2,2-Trichloromethylcarbinols are 1 are valuable synthetic intermediates with a multitude of uses. A scalable procedure for the synthesis of TMS-protected-2,2,2-trichloromethylcarbinols and 2,2,2-trichloromethylcarbinols 1 was developed that employs the in situ generation and reaction of trimethyl(trichloromethyl)silane (CCl(3)-TMS). The procedure avoids the exposure of the carbonyl compounds to the strongly basic conditions typically used for this transformation and also avoids isolation of the difficult-to-handle CCl(3)-TMS. This procedure was applied to diastereoselective trichloromethyl additions to 2-substituted 4-piperidinones and to reactions with a variety of structurally diverse aldehydes and ketones.

One-Pot in Situ Formation and Reaction of Trimethyl(trichloromethyl)silane: Application to the Synthesis of 2,2,2-Trichloromethylcarbinols

2,2,2-Trichloromethylcarbinols are 1 are valuable synthetic intermediates with a multitude of uses. A scalable procedure for the synthesis of TMS-protected-2,2,2-trichloromethylcarbinols and 2,2,2-trichloromethylcarbinols 1 was developed that employs the in situ generation and reaction of trimethyl(trichloromethyl)silane (CCl(3)-TMS). The procedure avoids the exposure of the carbonyl compounds to the strongly basic conditions typically used for this transformation and also avoids isolation of the difficult-to-handle CCl(3)-TMS. This procedure was applied to diastereoselective trichloromethyl additions to 2-substituted 4-piperidinones and to reactions with a variety of structurally diverse aldehydes and ketones.

ChemInform Abstract: Rhodium-Catalyzed Phenylation of N-Arylsulfonyl Aldimines with Sodium Tetraphenylborate or Trimethyl(phenyl)stannane.

Abstract The rhodium-catalyzed addition reactions of trimethyl(phenyl)stannane and sodium tetraphenylborate to N -phenylsulfonyl aldimines RCHNSO 2 Ph (R=alkyl and aryl) provided R(Ph)CHNHSO 2 Ph in high yields. A cationic and free phosphine complex [Rh(cod)(MeCN) 2 ]BF 4 was found to be an efficient catalyst for the addition of PhSnMe 3 , whereas [Rh(cod)(MeCN) 2 ]BF 4 /dppb catalyzed the addition of Ph 4 BNa to various N -sulfonyl aldimines in dioxane at 90°C. The scope and limitations of the reactions, as well as the effect of varying the reaction conditions, are discussed.

How Trimethyl(trifluoromethyl)silane Reacts with Itself in the Presence of Naked Fluoride—A One‐Pot Synthesis of Bis([15]crown‐5)cesium 1,1,1,3,5,5,5‐Heptafluoro‐2,4‐bis(trifluoromethyl)pentenide

Reactions of trimethyl(trifluoromethyl)silane in the presence of "naked" fluoride proceed up to a temperature of +5 degrees C mainly with formation of [Me3Si(CF3)2]-. A further rise of temperature up to about 20 degrees C gives evidence for the formation of a salt with the 1,1,1,2,3,6,6,6-octafluoro-2,4,4,5,5-pentakis(trifluoromethyl)hexan-3-ide anion. This intermediate decomposes at room temperature into the 1,1,1,3,5,5,5-heptafluoro-2,4-bis(trifluoromethyl)pentenide anion. The bis([15]crown-5)cesium salt, [Cs([15]crown-5)2][(CF3)2CCFC(CF3)2] has been characterized unambiguously as the stable final product of this reaction sequence. Thermal decomposition of this salt opens a convenient nontoxic route to obtain 1,1,3,3-tetrakis(trifluoromethyl)allene, (F3C)2C=C=C(CF3)2.

Evidence of single electron transfer in the diastereoselective synthesis of β-stannylketones

The reaction of trimethyl- and triphenylstannylpotassium with mono and disubstituted enones ( 1– 5) in acetonitrile as solvent was studied. In a few seconds and under mild conditions these reactions lead in nearly quantitative yields either to a mixture of diastereomers or to a pure diastereomer of β-stannylketones 6– 16. The reactions with triphenylstannylpotassium gave higher yields than trimethylstannylpotassium. The partial or total inhibition of the reactions by addition of a free radical scavenger (galvinoxyl) or a radical–anion scavenger ( p-dinitrobenzene) leads us to believe that these reactions could follow a two-stage reaction mechanism involving an initial electron transfer step. Our results indicate that these reactions are stereoselective but certainly not stereospecific. Full 1H- and 13C-NMR data of the new β-stannylketones are given.

A Chemical Scale for Evaluating the Electron Transfer Ability of Alkylcopper Reagents

Abstract In order to evaluate the electron transfer ability of organocopper reagents, the reactions of appropriate Michael acceptors with methyl- and butylcopper reagents were investigated. The reaction of trimethyl ethylene-1,1,2-tricarboxylate (1a) with methylcopper reagents gave a mixture of the conjugate adduct 2a and reduction product 3a in good to high yields. The ratio of 2a and 3a varied with the copper species and decreased in the following order: MeCu(CN)Li > MeCu > Me2Cu(CN)Li2 >> Me2CuLi > Me3CuLi2. It was confirmed by 13C NMR studies and oxidation experiments of the intermediate copper species that the reduction product 3a was produced via an electron transfer process and that the conjugate adduct 2a was afforded through a nucleophilic attack of MeCuILn. Consequently, the electron transfer ability of methylcopper reagents is in the following order: Me3CuLi2 > Me2CuLi >> Me2Cu(CN)Li2 > MeCu > MeCu(CN)Li. By similar experiments using 3-cyclopropyl-2-methoxycarbonyl-3-phenyl-2-propenoate (9) as a Michael acceptor, we concluded that the electron transfer ability of butylcopper reagents is in the order of Bu2CuLi > BuCu(CN)Li ≈ Bu2Cu(CN)Li2 > BuCu, and that its ability of butylcopper reagents is higher than that of the corresponding methylcopper reagents.

Palladium(0)/LiCl promoted cross-coupling reaction of (4-pyridyl)stannanes and aromatic bromides: Easy access to poly(4-pyridyl)-substituted aromatics

Abstract A PdCl 2 (PPh 3 ) 2 /LiCl catalyst effectively promoted the cross-coupling reaction of trimethyl(4-pyridyl)stannane and aromatic polybromides to offer easy access to poly(4-pyridyl)-substituted aromatic compounds.

Syntheses of antimony(v) derivatives from trimethyl and triphenylantimony(III), dihydric phenols, andtert-butyl hydroperoxide

Trimethyl and triphenylantimonyo-phenylene dioxides were obtained by the reaction of trimethyl- and triphenylantimony with pyrocatechol in the presence oftert-butyl hydroperoxide in 68 and 81 % yields, respectively. 7,7,7,15,15,15-Hexamethyl-(and phenyl)-6,8,14,16-tetraoxa-7, 15-distibatricyclo[11.3.1.19,13]octadeca-1,3,5,9,11,13-hexaenes were synthesized analogously by the reaction with resorcinol (in 79 and 93 % yields, respectively). The use of hydroquinone resulted in polymeric trimethyl- and triphenylantimony hydroquinolates.

ChemInform Abstract: Formation of Secondary Alcohols from the Reaction of Trimethyl‐ and Methyldiphenyltelluronium Salts with Aldehydes by Use of Organolithium Reagents.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Perkin communication. Formation of secondary alcohols from the reaction of trimethyl- and methyldiphenyl-telluronium salts with aldehydes by use of organolithium reagents

The telluronium salts (1) and (2), precursors of the non-stabilized telluronium ylide, on treatment with organolithium reagents, reacted with aldehydes to afford secondary alcohols via tetraorganyl tellurium intermediates.

ChemInform Abstract: Metacyclophanes and Related Compounds. Part 24. Preparation and Reaction of Trimethyl(2.2.2)‐ and Tetramethyl(2.2.2.2)metacyclophane.

AbstractThe metacyclophanes (VI) mentioned in the title are prepared by coupling the dichloride (I) with the dithiols (II), followed by Ramberg‐Baecklund ring contraction and de‐tert‐butylation.

Metacyclophanes and related compounds. 24. Preparation and reaction of trimethyl[2.2.2]- and tetramethyl[2.2.2.2]metacyclophane

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMetacyclophanes and related compounds. 24. Preparation and reaction of trimethyl[2.2.2]- and tetramethyl[2.2.2.2]metacyclophaneMasashi Tashiro, Tetsuya Watanabe, Akihiko Tsuge, Tsuyoshi Sawada, and Shuntaro MatakaCite this: J. Org. Chem. 1989, 54, 11, 2632–2638Publication Date (Print):May 1, 1989Publication History Published online1 May 2002Published inissue 1 May 1989https://doi.org/10.1021/jo00272a034RIGHTS & PERMISSIONSArticle Views115Altmetric-Citations14LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (806 KB) Get e-Alerts Get e-Alerts

ChemInform Abstract: Reactions of Halogen‐Containing O‐Silylated Enolates. Part 3. Reactions of Trimethyl(2,2‐dichloro‐1‐phenylvinyloxy)‐ and Trimethyl(4,4‐dichloro‐1‐methyl‐1,3‐butadienyloxy)silanes with α‐Chloro Ethers and Acid Chlorides.

ChemInform Abstract: Reactions of Halogen‐Containing O‐Silylated Enolates. Part 3. Reactions of Trimethyl(2,2‐dichloro‐1‐phenylvinyloxy)‐ and Trimethyl(4,4‐dichloro‐1‐methyl‐1,3‐butadienyloxy)silanes with α‐Chloro Ethers and Acid Chlorides.

ChemInform Abstract: Reactions of Halogen‐Containing O‐Silylated Enolates. Part 2. Reaction of Trimethyl(4,4‐dichloro‐2‐methyl‐1,3‐butadienyloxy)silane with α‐Chloro Ethers and Acid Chlorides.

AbstractThe silyl enol ether (I) reacts with the α‐chloro ethers (II) to give the aldehydes (III).