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Trimethylsilyl
Terms modified by Trimethylsilyl Selected AbstractsSynthesis of Pederic Acid and Related Model StudiesHELVETICA CHIMICA ACTA, Issue 5 2004Steffen Breitfelder {[2-(Trimethylsilyl)ethoxy]methyl} (SEM)-protected pederic acid 16 was prepared by deriving the stereogenic center at C(7) from mannitol and those at C(2) and C(3) (mycalamide numbering) from trans -2,3-dimethyloxirane. Routes to pederamides involving a late oxygenation at C(7) were explored. [source] ChemInform Abstract: Efficient Oxidative Deprotection of Trimethylsilyl, Tetrahydropyranyl and Methoxymethyl Ethers under Solvent-Free Conditions.CHEMINFORM, Issue 46 2008Farhad Shirini Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 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. [source] Silica-Supported bis(Trimethylsilyl) Chromate: Oxidation of Thiols to Their Corresponding Disulfides.CHEMINFORM, Issue 26 2007Majid M. Heravi Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] 4-Aminophenyldiphenylphosphinite (APDPP), a New Heterogeneous and Acid Scavenger Phosphinite , Conversion of Alcohols, Trimethylsilyl, and Tetrahydropyranyl Ethers to Alkyl Halides with Halogens or N-Halosuccinimides.CHEMINFORM, Issue 9 2007Nasser Iranpoor Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Silver(I)-Catalyzed Protiodesilylation of 1-(Trimethylsilyl)-1-alkynes.CHEMINFORM, Issue 35 2005Adriano Carpita No abstract is available for this article. [source] Construction of Terminal Conjugated Enynes: Regio- and Stereoselective Syntheses of 3-Alken-1-ynes and 1-Trimethylsilyl-3-alken-1-ynes from Alkenyldialkylboranes and (Trimethylsilyl)ethynyl Bromide.CHEMINFORM, Issue 44 2002Masayuki Hoshi Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: A Practical and Highly Efficient Synthesis of ,-(Trimethylsilyl)-difluoroacetates.CHEMINFORM, Issue 13 2001Hideki Amii Abstract ChemInform 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. [source] Synthesis, Structures, and Magnetic Properties of N -Trialkylsilyl-8-amidoquinoline Complexes of Chromium, Manganese, Iron, and Cobalt as well as of Wheel-Like Hexanuclear Iron(II) and Manganese(II) Bis(8-amidoquinoline)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2010Astrid Malassa Abstract The transamination of 8-(tert -butyldimethylsilylamino)quinoline with (thf)2Cr[N(SiMe3)2]2 yields monomeric bis[8-(tert -butyldimethylsilylamido)quinoline]chromium(II) (1). Similar reactions of M[N(SiMe3)2]2 (M = Mn, Fe, Co) with 8-(trialkylsilylamino)quinoline lead to the formation of monomeric bis[8-(trialkylsilylamido)quinoline]metal(II) [M = Mn, SiR3 = SiMe2tBu (2a), SiiPr3 (2b); M = Fe, SiR3 = SiMe2tBu (3a),SiiPr3 (3b); M = Co, SiR3 = SiMe2tBu (4a), SiiPr3 (4b)]. The transamination of 8-aminoquinoline with M[N(SiMe3)2]2 (M = Mn, Fe, Co) allows the isolation of the heteroleptic 1:1 and homoleptic 2:1 products. The 1:1 complexes bis[8-amidoquinoline metal(II)bis(trimethylsilyl)amide] [M = Mn (5), Fe (6), Co (7)] are dimeric with bridging 8-amidoquinoline moieties. The 2:1 complexes of Mn and Fe, bis(8-amidoquinoline)manganese(II) (8) and bis(8-amidoquinoline)iron(II) (9), form hexamers with wheel-like molecular structures consisting of metal-centered nitrogen octahedra interconnected by common N···N edges. The cobalt complex, bis(8-amidoquinoline)cobalt(II) (10), precipitates as a microcrystalline powder. Investigations of the magnetic properties by DFT corroborate the experimental data for the Mn derivative 8, where an antiferomagnetic coupling is observed. By contrast, calculations on the Fe6 -wheel 9 yield very close-lying ferromagnetically and antiferromagnetically coupled states. [source] Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Urs Fischbach Abstract The tetradendate phosphane tris(5H -dibenzo[a,d]cyclohepten-5-yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5-chloro-5H -dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X-ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky ,1 -phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (, = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M,C=Ctrop) and ,(31P) decreases with increasing M,C=Ctrop in the order 9 (, = 260 ppm) > 7 (, = 196 ppm) > 6 (, = 135 ppm) > 3 (, = ,30.9 ppm). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis and Structure of Trialkyltantalum Complexes Stabilized by Aminopyridinato LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006Awal Noor Abstract (4-Methylpyridin-2-yl)(trimethylsilyl)amine (1), (6-methylpyridin-2-yl)(trimethylsilyl)amine (2), and (2,6-diisopropylphenyl)(pyridin-2-yl)amine (3) were deprotonated and used as ligands to synthesize trialkyltantalum complexes. The reaction of 2 equiv. of 1 or 2 with pentabenzyltantalum afforded tribenzyltantalum(V) complexes by toluene elimination. Analogous reaction using 3 failed. Lithiation of 3 followed by the reaction with tribenzyltantalum dichloride gave rise to the corresponding tribenzyl complex. Other alkyltantalum complexes stabilized by this ligand environment can be prepared by treating tantalum pentachloride with 2 equiv. oflithiated 3 to form a bis(aminopyridinato)tantalum trichloride. The reaction of this trichloride with 3 equiv. of alkyllithium compounds like methyllithium affords the corresponding trialkyltantalum complexes. X-ray diffraction studies of four of the synthesized complexes were carried out. They adopt two different coordination environments, either slightly distorted capped octahedrons (sterically less demanding aminopyridinato ligands) or pentagonal bipyramids (bulkier aminopyridinato ligands). The alkyl species were surprisingly stable at elevated temperatures and no formation of mixed alkyl/alkylidene complexes was observed. Alkyl cation formation and the behaviour of a selection of these compounds in olefin polymerization were explored. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Generation and Reactions of Overcrowded Diaryldilithiostannane and DiaryldipotassiostannaneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005Tomoyuki Tajima Abstract Exhaustive reduction of an overcrowded dibromostannane bearing two bulky aromatic substituents, Tbt(Dip)SnBr2 {Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Dip = 2,6-diisopropylphenyl}, with an excess amount of lithium naphthalenide in THF at ,78 °C gave the corresponding dilithiostannane, Tbt(Dip)SnLi2, the generation of which was confirmed by trapping experiments with some electrophiles together with 119Sn and 7Li NMR spectroscopy. The diaryldilithiostannane was found to be stable in solution under an inert gas below ,25 °C. The potassium analogue, Tbt(Dip)SnK2, was also generated by the reduction of the dibromostannane in THF at ,78 °C by the use of KC8 as a reductant. The reactions of dilithiostannane and dipotassiostannane obtained with o -dibromobenzene did not give a stannacyclopropabenzene derivative but an unexpected cyclization product, a stannacyclobutabenzene derivative, in contrast to thereactions of the corresponding dilithiosilane and dilithiogermane, Tbt(Dip)ELi2 (E = Si, Ge), with o -dibromobenzene leading to the formation of the corresponding metallacyclopropabenzenes as stable crystalline compounds. A preliminary result of the synthesis of a tin,tellurium double-bond compound from the dilithiostannane is also presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthetic Explorations Towards Sterically Crowded 1,2,3-Substituted Bis(indenyl)zirconium(IV) DichloridesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2005Andreas C. Möller Abstract The systematic synthesis of 1,3-dialkyl-substituted 2-silylindenes and their suitability as zirconocene ligands is discussed. Unexpected reactivities rendered a number of substitution patterns unfeasible, especially for alkyl groups other than methyl in 2-(trimethylsilyl)indene derivatives, and essentially for all derivatives of 2-(dimethylsilyl)indene. The syntheses of rac/meso -bis[1-methyl-2-(trimethylsilyl)indenyl]zirconium(IV) dichloride (12) and bis[1,3-dimethyl-2-(trimethylsilyl)indenyl]zirconium(IV) dichloride (13b) are described. The solid-state structure of the latter displays strong deformations within the ligand framework and an unusually large Cpcentroid -Zr,Cpcentroid angle. Both, 12/MAO and 13b/MAO, displayed ethene and ethene-co-1-hexene polymerization activity. Curiously, 13b/MAO shows an extraordinary monomer selectivity, which can be rationalized by means of DFT calculations on the active site. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis, Structure, and Reactivity of Novel Intramolecularly Coordinated Organolead(II) CompoundsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2003Klaus Jurkschat Abstract The intramolecularly coordinated heteroleptic organolead(II) compounds {4- tBu-2,6-[P(O)(OEt)2]2C6H2}PbX (2, X = Cl; 3, X = SPh) have been synthesized. Single-crystal X-ray analyses reveal that both compounds adopt polymeric chain structures by intermolecular Pb,X···Pb bridges, a structural motif previously unknown for organolead(II) derivatives. Compound 2 reacts with lithium diisopropylamide, iPr2NLi, and lithium bis(trimethylsilyl)methane, (Me3Si)2CHLi, respectively, to provide in situ the corresponding organolead(II) compounds {4- tBu-2,6-[P(O)(OEt)2]2C6H2}PbX (4, X = iPr2N; 5, X = (Me3Si)2CH], which were identified by NMR spectroscopy but could not be obtained as analytically pure substances. Attempts to isolate the intramolecularly coordinated organolead(II) hexafluorophosphate {4- tBu-2,6-[P(O)(OEt)2]2C6H2}Pb+PF6, from the reaction of 2 with TlPF6 also failed. Instead, the unprecedented salt [{5- tBu-1,3-[P(O)(OEt)2]2C6H3}4·(Pb2F)] [PF6]3·4THF (6) was obtained, in which the [(Pb,F,Pb)]3+ cation is stabilized by eight intermolecular P=O,Pb interactions. Compound 6 was characterized by single-crystal X-ray analysis and electrospray mass spectrometry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Development of Ketoside-Type Analogues of Trehalose by Using ,-Stereoselective O-Glycosidation of KetoseEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2007Rie Namme Abstract The stereoselective synthesis of ketoside-type analogues of trehalose is described. O-Glycosidation of hept-2-ulopyranose with trimethylsilyl ,-pyranoside promoted by trimethylsilyl trifluoromethanesulfonate afforded ,-ketopyranosyl ,-aldopyranosides exclusively. ,-Ketopyranosyl ,-aldooyranosides and ,-ketopyranosyl ,-ketopyranosides were also synthesized in a similar manner. The benzyl protecting groups of the hydroxy moieties were removed by hydrogenolysis to afford fully deprotected trehalose analogues.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Enantio- and Diastereomerically Pure Decalins by Deslongchamps-Type Annulation of Dienolates Containing a Chiral Lactone SubstituentEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2007Thomas Tricotet Abstract A conceptionally novel 1,3-asymmetric induction has been established. It controls the relative and absolute configuration of up to 5 stereocenters. They emerge from the anionic Diels,Alder reactions ("Deslongchamps annulations") between oxocyclohexenecarboxylates 25, 29 and dienolates 26, 30. The latter contain a ,-lactone. A Ph3Si,CH2 substituent therein controls the asymmetry of C,C bond formation with ds , 10:1. Strangely, the preferred sense of attack of the dienophile is contrasteric. Cycloadduct 31 was processed by an unprecedented fluoride-induced ambient-temperature tandem fragmentation. It turned the lactone moiety into an allyl group and the ,-oxo (trimethylsilyl)ethyl ester into a ketone. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Microwave-Assisted Heck Reaction in Poly(ethylene glycol) for the Synthesis of BenzazepinesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2007Valérie Declerck Abstract The Heck reaction of alkylated 2-(trimethylsilyl)ethanesulfonyl (SES)-protected ,-amino esters provides benzazepines in good yields. Good selectivity towards cyclisation was obtained when the reaction was performed in PEG 3400 as the solvent under microwave activation. Cleavage of the SES group with HF provides the corresponding free benzazepine. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Sodium Bis(trimethylsilyl)amide in the Oxidative Conversion of Aldehydes to NitrilesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2006Jih Ru Hwu Abstract The feasibility of the Me3Si species acting as a nucleofuge was investigated in compounds containing the NSiMe3 moiety. Treatment of various aromatic aldehydes with 2.2 equiv. of NaN(SiMe3)2 at 185 °C in a sealed tube produced the corresponding nitriles in high yields (81,98,%). In these reactions, NaN(SiMe3)2 acted as an oxidizing agent. Results from control experiments indicate that the Me3Si unit can depart efficiently from the NSiMe3 moiety of N -silylimine intermediates. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] The Formation of Silylated ,-Lactams from Silylketenes through Lewis Acid Promoted [2+2] Cycloaddition: A Combined Theoretical and Experimental StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2005Béatrice Pelotier Abstract The stereoselective formation of silylated cis -,-lactams from (trimethylsilyl)ketene and an ,-imino ester by Lewis acid catalysis is described. Theoretical results suggest that the reaction between (trimethylsilyl)ketene and trans -(methoxycarbonyl)- N -methylformaldimine would proceed most favourably with the BF3 catalyst coordinated to the ketene. Moreover, the calculated energy barriers account for the cis:trans ratio found experimentally. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] The turnover of carbohydrate carbon in a cultivated soil estimated by 13C natural abundancesEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2006D. Derrien Summary Understanding the chemical composition of soil organic matter (SOM) requires the determination of the dynamics of each class of compounds. We measured the dynamics of carbon in neutral carbohydrates by use of natural 13C labelling in an experimental wheat and maize sequence extending over 23 years. The isotopic composition of individual neutral monosaccharides was determined in hydrolysed particle-size fractions by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) of trimethylsilyl (TMS) derivatives. The sensitivity in terms of 13C/12C ratios ranged between 1 and 2, depending on the monosaccharide. The age distribution of neutral sugar carbon was very similar to that of total soil carbon. Particulate organic matter (POM) was characterized by the predominance of glucose and xylose of vegetal origin. In POM >,200 µm, the mean age of sugar-C (5 years) was slightly less than that of total carbon (7 years). Xylose was younger than glucose. The fine fraction 0,50 µm contained mainly glucose, arabinose, galactose, xylose, fucose and mannose, which had predominantly microbial origins. The mean age of carbohydrate carbon in the fraction 0,50 µm was between 60 and 100 years and was similar to that of total organic carbon (OC). No difference in the age of carbon between the individual monosaccharides was found. The POM fraction 50,200 µm had an intermediate signature and turnover. Considering the typical lability of carbohydrates, the relatively great age of carbohydrate carbon may be explained by physical or chemical protection from degradation, as well as by recycling of soil organic matter carbon by soil microbes. [source] The Tris(trimethylsilyl)silane/Thiol Reducing System: A Tool for Measuring Rate Constants for Reactions of Carbon-Centered Radicals with ThiolsHELVETICA CHIMICA ACTA, Issue 10 2006Chryssostomos Chatgilialoglu Abstract An extension of the well-known ,free-radical-clock' methodology is described that allows one to determine the rate constants of carbon-centered radicals with a variety of thiols by using the tris(trimethylsilyl)silane/thiol couple as a reducing system. A total of 20 rate constants for the hydrogen abstraction from a variety of alkyl-, silyl-, and aryl-substituted thiols by the primary-alkyl radical 2 in toluene at 80° were determined with the aid of the 5- exo-trig cyclization as a timing device. Further, seven rate constants for the hydrogen abstraction from a variety of alkyl- and silyl-substituted thiols by the acyl radical 9 in benzene at 80° were measured using the decarbonylation process as a timing device. The rate constants varied over two orders of magnitude from 106 to 108,M,1 s,1. Substituent effects were rationalized. The radical-trapping abilities of these reducing systems and those of other common hydrogen donors were compared. [source] Oligo(triacetylene) Derivatives with Pendant Long Alkyl ChainsHELVETICA CHIMICA ACTA, Issue 6 2004Jean-François Nierengarten Substituted (E)-2-(ethynyl)but-2-ene and (E)-hex-3-ene-1,5-diyne derivatives 6 and 10, respectively, were prepared by dicyclohexylcarbodiimide(DCC)-mediated esterification of tris(dodecyloxy)benzoic acid (4) with (E)-2-[(triisopropylsilyl)ethynyl]but-2-ene-1,4-diol (3) and (E)-2,3-bis[(trimethylsilyl)ethynyl]but-2-ene-1,4-diol (8), respectively, followed by deprotection with Bu4NF in wet THF (Schemes,1 and 2). Oligomerization reactions of diyne derivative 10 were attempted by treatment with the Hay catalyst in the presence of mono-alkyne 6 as an end-capping reagent. Under these conditions, only compound 7 resulting from the homocoupling of 6 (Scheme,1), and polymers of 10 were obtained due to the difference in reactivity of the alkyne groups in 6 and 10. In contrast, when phenylacetylene was used as the stopper, the oligomerization of 10 afforded a mixture of end-capped oligomers, from which 11,13 were isolated by column chromatography (Scheme,3). The poly(triacetylenes) (PTA) 16,18 were prepared in a similar manner starting from diol 8 and stearic acid (Schemes,4 and 5). Whereas the end-capped monomers and dimers 11, 12, 16, and 17 with pendant long alkyl chains do not exhibit any liquid-crystalline behavior, the trimeric derivatives 13 and 18 show mesomorphic properties, thus demonstrating that the poly(triacetylene) backbone can behave as a mesogenic unit. [source] Synthesis of new organophosphorus-substituted mono- and bis(trimethylsilyl)amines with PCH2N fragments and their derivativesHETEROATOM CHEMISTRY, Issue 2 2010Andrey A. Prishchenko Convenient procedures for the synthesis of new organophosphorus-substituted mono- and bis(trimethylsilyl)amines with PCH2N moiety are proposed, starting from trimethylsilyl esters of organophosphorus acids, as well as 1,3,5-trialkylhexahydro-1,3,5-triazines and N -alkoxymethyl bis(trimethylsilyl)amines as aminomethylating reagents. Certain properties of the resulting compounds are presented. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:71,77, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20580 [source] Chalcogenation reactions of a stable ferrocenyldiphosphene: Formation of thia-, selena-, and telluradiphosphiranes,HETEROATOM CHEMISTRY, Issue 5 2008Noriyoshi Nagahora The reactions of TbtPPTbt (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl) with elemental sulfur and selenium in the presence of triethylamine resulted in the formation of the corresponding thia- and selenadiphosphiranes in 71% and 65%, respectively, whereas the tellurization reaction was unsuccessful probably due to the steric reason. On the other hand, treatment of TbtPPFc (Fc = ferrocenyl) with elemental sulfur, selenium, and tributylphosphine telluride afforded the corresponding thia-, selena-, and telluradiphosphiranes in 84%, 88%, and 66% yields, respectively. The molecular structures of these three-membered heterocyclic compounds were confirmed by spectroscopic analysis. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:443,449, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20449 [source] Synthesis of 2-substituted O,O -bis(trimethylsilyl) alkylphosphonites with aryl and heterocyclic fragments and their amino or amido derivativesHETEROATOM CHEMISTRY, Issue 4 2008Andrey A. Prishchenko Free-radical addition of bis(trimethyl-siloxy)phosphine to various functionalized alkenes with aryl and heterocyclic fragments is proposed as a convenient procedure for the synthesis of new 2-substituted alkylphosphonites of corresponding structures. Also the new functionalized derivatives of these phosphonites, including various amino and amido groups as well as certain properties of these compounds, are presented. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:345,351, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20431 [source] Phosphorylation of N -Silylpyrroles with Phosphorus TribromideHETEROATOM CHEMISTRY, Issue 1 2008Aleksandra A. Chaikovskaya Phosphorylation of N -trimethylsilyl- and N -dimethyl-tert-butylsilylpyrroles with phosphorus tribromide in pyridine proceeds selectively at position 3 of the pyrrole ring. Removal of the trialkylsilyl protecting group has furnished the first representatives of N -unsubstituted 3-phosphorylated pyrroles. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:93,96, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20416 [source] The Pummerer-like reaction of 2,5-bis(trimethylsilyl)thiophene S -oxide with trifluoroacetic anhydride: intermediary formation of sulfurane [10- S -4(C2O2)] (,4 -sulfane)HETEROATOM CHEMISTRY, Issue 5 2001Soichi Sato On treatment of a 2,5-bissilylsubstituted thiophene S-oxide or dibenzothiophene S-oxide with trifluoroacetic anhydride, the equillibria between the corresponding substrates and hypervalent sulfur compounds (sulfurane or ,4 -sulfane) have now been first detected by low temperature NMR experiments. By elevating the temperature to room temperature, in the case of the thiophene S-oxide, the sulfurane detected was converted to 3-thiolene-2-one quantitatively via a Pummerer-like reaction. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:444,450, 2001 [source] ,-Ionone reactions with the nitrate radical: Rate constant and gas-phase productsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2009Joel C. Harrison The bimolecular rate constant of k (9.4 ± 2.4 × 10,12 cm3 molecule,1 s,1 was measured using the relative rate technique for the reaction of the nitrate radical (NO3,) with 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-3-buten-2-one (,-ionone) at (297 ± 3) K and 1 atmosphere total pressure. In addition, the products of ,-ionone + NO3, reaction were also investigated. The identified reaction products were glyoxal (HC(O)C(O)H), and methylglyoxal (CH3C(O)C(O)H). Derivatizing agents O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and N,O-bis(trimethylsilyl)trifluoroacetamide were used to propose the other major reaction products: 3-oxobutane-1,2-diyl nitrate, 2,6,6-trimethylcyclohex-1-ene-carbaldehyde, 2-oxo-1-(2,6,6-trimethylcyclohex-1-en-1-yl)ethyl nitrate, pentane-2,4-dione, 3-oxo-1-(2,6,6-trimethylcyclohex-1-en-1-yl)butane-1,2-diyl dinitrate, 3,3-dimethylcyclohexane-1,2-dione, and 4-oxopent-2-enal. The elucidation of these products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible ,-ionone + NO3, reaction mechanisms based on previously published volatile organic compound + NO3, gas-phase mechanisms. The additional gas-phase products 5-acetyl-2-ethylidene-3-methylcyclopentyl nitrate, 1-(1-hydroxy-7,7-dimethyl-2,3,4,5,6,7-hexahydro-1 H-inden-2-yl)ethanone, 1-(1-hydroxy-3a,7-dimethyl-2,3,3a,4,5,6,-hexahydro-1 H-inden-2-yl)ethanone, and 5-acetyl-2-ethylidene-3-methylcyclopentanone are proposed to be the result of cyclization through a reaction intermediate. © 2009 Wiley Periodicals, Inc., Int J Chem Kinet 41: 629,641, 2009 [source] The hydroxyl radical reaction rate constant and products of 3,5-dimethyl-1-hexyn-3-ol,INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2004J. R. Wells A bimolecular rate constant,kDHO, of (29 ± 9) × 10,12 cm3 molecule,1 s,1 was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with 3,5-dimethyl-1-hexyn-3-ol (DHO, HCCC(OH)(CH3)CH2CH(CH3)2) at (297 ± 3) K and 1 atm total pressure. To more clearly define DHO's indoor environment degradation mechanism, the products of the DHO + OH reaction were also investigated. The positively identified DHO/OH reaction products were acetone ((CH3)2CO), 3-butyne-2-one (3B2O, HCCC(O)(CH3)), 2-methyl-propanal (2MP, H(O)CCH(CH3)2), 4-methyl-2-pentanone (MIBK, CH3C(O)CH2CH(CH3)2), ethanedial (GLY, HC(O)C(O)H), 2-oxopropanal (MGLY, CH3C(O)C(O)H), and 2,3-butanedione (23BD, CH3C(O)C(O)CH3). The yields of 3B2O and MIBK from the DHO/OH reaction were (8.4 ± 0.3) and (26 ± 2)%, respectively. The use of derivatizing agents O -(2,3,4,5,6-pentalfluorobenzyl)hydroxylamine (PFBHA) and N,O -bis(trimethylsilyl)trifluoroacetamide (BSTFA) clearly indicated that several other reaction products were formed. The elucidation of these other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible DHO/OH reaction mechanisms based on previously published volatile organic compound/OH gas-phase reaction mechanisms. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 534,544, 2004 [source] N-Heterocyclic Carbene-Mediated Organocatalytic Transfer of Tin onto Aldehydes: New Access to ,-Silyloxyalkylstannanes and ,-SilyloxyallylstannanesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2010Romain Blanc Abstract A new, highly efficient and mild N-heterocyclic carbene (NHC)-mediated organocatalytic procedure for the transfer of tin from tributyl(trimethylsilyl)stannane (Bu3SnSiMe3) onto aldehydes for the preparation of ,-silyloxyalkylstannanes and ,-silyloxyallylstannanes has been developed. [source] Room Temperature Lewis Base-Catalyzed Alumination of Terminal AlkynesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Yuhan Zhou Abstract An efficient and mild access to mixed dimethylalkynylaluminum reagents has been developed via a direct Lewis base-catalyzed alumination of terminal alkynes by trimethylaluminum. The use of bis(trimethylsilyl)methylamine enables the metalation at room temperature with only 1% of catalyst loading. [source] | ||||||||||||||||||||||||||||||||||