- Cyanogen formation during asymmetric cyanohydrin synthesis
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During asymmetric cyanohydrin synthesis catalysed by vanadium Voxo(salen) complexes, the catalysts are reduced to vanadium IVoxo(salen) as determined by EPR spectroscopy; the reducing agent is cyanide which is oxidised to cyanogen via a non-radical mechanism.
- Chechik, Victor,Conte, Marco,Dransfield, Trevor,North, Michael,Omedes-Pujol, Marta
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- Photochemical synthesis of a stable terminal uranium(VI) nitride
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Terminal uranium nitrides have so far proven impossible to isolate by photolysis of azides. Here we report the second ever example of an isolated terminal uranium(VI) nitride. We show that the terminal nitride [NBu4][U(OSi(OtBu)3)4(N)], 3, can be prepared upon photolysis with UV light of the U(IV) azide analogue. This is achieved by careful tailoring of the azide precursor and of the reaction conditions. Complex 3 is stable under ambient conditions but reacts readily with electrophiles (H+ and CO).
- Barluzzi, Luciano,Scopelliti, Rosario,Mazzanti, Marinella
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- Synthesis of N-nitro-N′-(trimethylsilyl)carbodiimide
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Nitration of N,N′-bis(trimethylsilyl)carbodiimide with N2O5 or (NO2)2SiF6 afforded N-nitro-N′-(trimethylsilyl)carbodiimide, the first representative of N-nitro carbodiimides. Its further nitration led
- Churakov,Ioffe,Voronin,Tartakovsky
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- Efficient synthesis of trimethylsilyl pseudohalides catalyzed by PEG400/ZnI2 under ultrasound irradiation
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Trimethylsilyl pseudohalides Me3SiX, where X = NCS, NCO, or CN, were readily prepared conveniently in desirable yields by the reaction of Me3SiCl with NaX or KX catalyzed by PEG400 and zinc iodide under ultrasound irradiation. Copyright Taylor & Francis, Inc.
- Sufang, Wang,Shaobing, Wang,Yongshen, Xu
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- Catalytic production of isocyanates via orthogonal atom and group transfers employing a shared formal group 6 M(II)/M(IV) redox cycle
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Under an atmosphere of CO, the Mo(IV) imido complex CpMo[N( iPr)C(Me)N(iPr)](NSiMe3) (Cp* = η5-C5Me5) (1) serves as a catalyst for production of an isocyanate via metal-mediated nitrene group transfer in benzene solution under mild conditions (55 °C, 10 psi) according to RN3 + CO → N2 + RNCO. Mechanistic and structural studies support a catalytic cycle for nitrene group transfer involving formal Mo(II) monocarbonyl and Mo(IV) (κ2-C,N)-isocyanate intermediates. These results complement an earlier finding that catalytic production of isocyanates can alternatively proceed through oxygen-atom transfer and an isomeric Mo(IV) (κ2-C,O)-isocyanate according to N2O + CNR → N2 + RNCO.
- Yonke, Brendan L.,Reeds, Jonathan P.,Fontaine, Philip P.,Zavalij, Peter Y.,Sita, Lawrence R.
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- THE MOLECULAR STRUCTURE OF TRIMETHYLSILYLISOCYANATE IN THE GAS PHASE REDETERMINED BY ELECTRON DIFRACTION
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We have redetermined the molecular structure of trimethylsilylisocyanate in the gas phase by electron diffraction.An ra structure is defined with bond distances (pm) SiN 174.0(4), SiC 186.4(2), N=C 120.2(16), C=O 117.6(10) and CH 109.9(5), bond angles (degrees) HCSi 109.0(9), CSiC 108.8(25), SiNC 156.9(30) and NCO 165.8(36), with the N=C bond eclipsing one Si-C bond and the Me3Si group tilted sligthly.The methyl groups are twisted 26.9(35) deg from the position giving the Me3Si group C3v symmetry in an (assumed) concerted fashion.The apparent deviations from linearity of the SiNCO skeleton are shown to be compatible with a pseudolinear structure similar to that of SiH3NCO.
- Cradock, Stephen,Huntley, Christopher M.,Durig, J. R.
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- New aspects of isocyanate synthesis with the use of O-silylurethanes
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Silyl group at the nitrogen atom in the O-silylurethanes drastically affects the thermolysis processes and allows one to simplify the synthesis of methyl- and trimethylsilyl isocyanates.
- Kirilin, Aleksei D.,Belova, Liya O.,Pletneva, Maria V.,Golub, Nataliya A.,Storozhenko, Pavel A.,Kirilina, Nadezhda I.
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- Syntheses and characterizations of iron complexes of bulky: O -phenylenediamide ligand
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We report the syntheses of a family of tetrahedral iron complexes bearing a bulky redox active o-phenylenediamide ligand. The electronic structures of these complexes have been investigated by M?ssbauer spectroscopy, magnetic susceptibility measurements, and X-ray crystallography.
- Demuth, Joshua C.,Liang, Qiuming,Lin, Jack H.,Neidig, Michael L.,Song, Datong
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- Trimethylsilyl Pseudohalide Adducts of GaCl3 and B(C6F5)3
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Me3Si?X (X=CN, N3, OCN, and SCN) was treated with the Lewis acids GaCl3 and B(C6F5)3 in toluene yielding the desired adducts Me3Si?X→GaCl3 and Me3Si?X→B(C6F5)3. All synthesized adducts were isolated and completely characterized including single crystal structure elucidations. The different structures, thermodynamics of formation and charge transfer effects are discussed on the basis of experimental and theoretical data.
- Bl?sing, Kevin,Bresien, Jonas,Maurer, Steffen,Schulz, Axel,Villinger, Alexander
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supporting information
p. 1913 - 1920
(2021/05/10)
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- Stoichiometric Reactions of CO2 and Indium-Silylamides and Catalytic Synthesis of Ureas
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The indium compounds In(N(SiMe3)2)2Cl?THF (2) and In(N(SiMe3)2)Cl2?(THF)n (3) were shown to react with CO2 to give [(Me3Si)2N)InX(μ-OSiMe3)]2 (X=N(SiMe3)2 4, Cl 5). 0.05–2.0 mol % of the species 3 acts as a pre-catalyst for the conversion of aryl and alkyl silylamines under CO2 (2–3 atm) to give the corresponding ureas in 70–99 % yields. A proposed mechanism is supported by experimental and computational data.
- Xu, Maotong,Jupp, Andrew R.,Stephan, Douglas W.
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supporting information
p. 14277 - 14281
(2017/10/31)
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- Metal-Mediated Production of Isocyanates, R3EN=C=O from Dinitrogen, Carbon Dioxide, and R3ECl
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A highly efficient and versatile chemical cycle has been developed for the production of isocyanates through the molecular fixation of N2, CO2 and R3ECl (E=C, Si, and Ge). Key steps include a 'one-pot' photolytic N-N bond cleavage of a Group6 dinuclear dinitrogen complex with insitu trapping by R3ECl to provide a metal terminal imido complex that can engage in simultaneous nitrene-group transfer and oxygen-atom transfer to generate an intermediate metal terminal oxo complex with release of the isocyanate product. Reaction of the oxo complex with additional equivalents of R3ECl regenerates a metal dichloride that is the precursor for dinuclear dinitrogen starting material.
- Keane, Andrew J.,Farrell, Wesley S.,Yonke, Brendan L.,Zavalij, Peter Y.,Sita, Lawrence R.
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supporting information
p. 10220 - 10224
(2015/09/01)
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- A new three-step procedure for the synthesis of cyanuric acid from urea
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A new procedure for preparing high-purity cyanuric acid from urea was suggested and experimentally checked. The procedure is based on urea silylation, followed by pyrolysis of the silyl derivative and fractional distillation of the trimethylsilyl isocyanate formed, for which the temperature limits of mild hydrolysis were determined.
- Lebedev,Sheludyakov,Lebedeva
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p. 793 - 795
(2015/03/04)
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- A study on the haterogeneous reaction of trialkylsilyl chlorides with inorganic salts and monocarboxylates catalysed by PEG400
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The important and useful trialkylsilyl pseudohalides R3SiX, where X=NCS, NCO, N3 or CN and R=methyl or ethyl, and trimethylsilyl monocarboxylates, where X=RCOO, were readily prepared in high yields by nucleophilic substitution of R3SiCl with X ions provided by NaX or KX at room temperature catalysed by PEG400 and zinc iodide. The reactions of trimethylsilyl chloride with some metal oxysalts were also studied for the first time.
- Du, Yun-Fei,Cao, Yu-Qing,Dai, Zhi,Chen, Bao-Hua
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p. 223 - 225
(2007/10/03)
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- Pacidamycins produced by Streptomyces coeruleorubidus
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The invention provides novel antibiotics of the pacidamycin group of uridyl peptide antibiotics and methods of preparing and using those compounds.
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- Organosilicon and organotin derivatives of urea in transmetallation reactions
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Reaction of N-trimethylsilyl-N′-phenylurea with bis(tributylstannyl) oxide in refluxing THF yields tributylstannyl isocyanate and aniline as the main products, while in the case of triphenylstannyl chloride N-triphenylstannyl-N′-phenylurea can be prepared. Its thermal decomposition yields triphenylstannyl isocyanate and aniline. Reaction of N,N′-bis(trimethylstannyl)urea with (Bu3Sn)2O gives Bu3Sn-N=C=O, HMDS, and ammonia.
- Gordetsov,Kulagina,Zimina
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p. 409 - 412
(2007/10/03)
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- New anti-inflammatory steroids : [16α,17α-d] isoxazoline derivatives of prednisolone and 9α-fluoroprednisolone
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Novel anti-inflammatory steroids; 11β,21-dihydroxy-3,20-dioxo-1,4-pregnadiene-[16α, 17α-d]isoxazoline, 4a, and 9α-fluoro-11β,21-dihydroxy-3,20-dioxo-1,4-pregnadiene-[16α, 17α-d]isoxazoline, 4b, and their 21-acetate derivatives, 5a and 5b, were synthesized via 1,3-dipolar cycloaddition of fulminic acid to the corresponding 1,4,16-pregnatriene-3,20-diones 2a,b and 3a,b. The topical anti-inflammatory activities of these [16α,17α-d]isoxazoline steroids were assessed in the croton oil-induced ear edema bioassay. In this study, all the test compounds displayed higher anti-inflammatory activity than hydrocortisone (relative potency of 1.0) as shown by their relative potencies of 6.8, 4.3, 3.3, 1.9 and 2.2 for 5b, 4b, 5a, 4a and 1a, respectively. In the semichronic multiple dose study, prednisolone, 1a, displayed significant suppressive effects on normal body weight gain, corticosterone levels, adrenal and thymus weights. No significant suppressive effects on these parameters were noted with any of the new compounds. They displayed higher local to systemic activity ratios than prednisolone. Results gathered from these studies confirm that fusion of isoxazoline ring to C-16/C-17 positions, fluorination at 9α-position and acetylation of the 21-hydroxyl group of corticosteroid molecule are useful manipulations for the enhancement of local anti-inflammatory activity and reduction of systemic side effects.
- Khalil, Mounir A.,Maponya, Mamakiri F.,Ko, Dong-Hoon,You, Zhengqing,Oriaku, Ebenezer T.,Lee, Henry Joung
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- Reactions of Iso(thio)cyanato Derivatives of Three- and Four-Coordinate Phosphorus with Trimethylsilyldiethylamine
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Iso(thio)cyanato(thio)phosphates (-phosphonates, -phosphinates) take up trimethylsilyldiethylamine to form phosphorus- and silicon-containing (thio)ureas. Simultaneous introduction to the phosphorus atom of an urea (thiourea) moiety and a chloromethyl group, followed by intramolecular cyclization under the action of a base, yields 1,3,4-oxaza(thiaza)phospholines. Linear and cyclic P(III) isothiocyanato derivatives react with trimethylsilyldiethylamine with substitution of the isocyanato group by a diethylamino group and formation of the corresponding phosphoramidites.
- Pudovik,Krepysheva,Al'myanova,Kamalov,Pudovik
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p. 349 - 352
(2007/10/03)
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- Gas- Phase Ion Chemistry of Siloxide and Silamide Ions by Using the Flowing Afterglow. Unusual Rearrangements Involving SiO and SiS Bond Formation
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Siloxide ions undergo O/S exchange reactions with suitable sulfur-containing neutrals, e.g.H3SiO- + CS2 -> H3SiS- + COS.Silamide ions similarly undergo NR/O and NR/S exchange reactions together with nucleophilic displacement reactions, e.g.: .No simple correlation between rate and mechanism is observed for all the studied reactions.
- O'Hair, Richard A.J.,Sheldon, John C.,Bowie, John H.,Damrauer, Robert,DePuy, Charles H.
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p. 489 - 496
(2007/10/02)
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- ULTRAVIOLET SPECTROSCOPIC INVESTIGATION OF ISOCYANATO- AND ISOTHIOCYANATO SILANES CONTAINING PHENYL- AND METHYL GROUPS
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The members of the series R(n)Si(NCO)(4-n) and R(n)Si(NCS)(4-n), where R = -CH3 and -C6H5, were prepared, their ultraviolet spectra recorded and the observed bands assigned.The spectra were compared to those of halogeno derivatives.The similarity of halogen- and pseudohalogeno-groups and difference between the effect of methyl- and phenyl-groups were studied.
- Veszpremi, Tamas,Barta, Istvan,Nagy, Jozsef
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p. 243 - 250
(2007/10/02)
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- Carbene Reactions, XX. Structural Aspects Responsible for the Thermal Extrusion of Carbenes from Norbornadienes
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The notion is put forward that norbornadienes having weak donor substituents at C-7 should suffer homolysis of the C-1/C-7 bond on heating, leading via the diradical 6 to either cycloheptatrienes or benzylic compounds.In contrast, norbornadienes having strong donor systems at C-7 should suffer heterolysis of the C-1/C-7 bond, whereupon the resulting zwitterion 7 collapses directly to carbenes in a singlet ground state.
- Hoffmann, Reinhard W.,Barth, Wolfgang,Schuettler, Reinhard,Mayer, Bernhard
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p. 3297 - 3315
(2007/10/02)
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- SYNTHESIS AND REARRANGEMENT OF CYCLOADDUCTS FROM TRIMETHYLSILANECARBONITRILE OXIDE
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The cycloadducts from trimethylsilanecarbonitrile oxide and ethylenic or acetylenic compounds easily rearrange to open-chain intermediates, which, in turn, are hydrolysed respectively to β-hydroxynitriles and β-oxonitriles.The cycloadducts of the same nitrile oxide with sulfur dioxide and sulfinylamines are unstable, too, leading respectively to trimethylsilylisocyanate and trimethylsilylcarbodiimides.All these reactions are of preparative interest, in comparison with previous methods.
- Sarlo, Francesco De,Brandi, Alberto,Goti, Andrea,Guarna, Antonio,Rovero, Paolo
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p. 511 - 518
(2007/10/02)
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- PSEUDOHALOGEN CHARACTER OF THE HETEROCUMULENE GROUP IN GEM-DI(HETEROCUMULENO)ALKANES
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In the reactions of gem-di(heterocumuleno)alkanes with triphenylphosphoranediylaminotrimethylsilane or N-(trimethylsilyl)diphenylketimine one heterocumulene group (isocyanate or carbodiimide) exhibits pseudohalogen characteristics.A new rearrangement with migration of the N=C(C6H5)2 group was discovered in the azaallyl triad C=N-C.
- Gorbatenko, V. I.,Mel'nichenko, N. V.,Samarai, L. I.
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p. 2020 - 2023
(2007/10/02)
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- N-ALKYLIDENECARBAMOYL ISOCYANATES. REACTION OF TERTIARY α-FLUOROAMINE WITH TRIMETHYLSILYL ISOCYANATE
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The reaction of (1,1,2-trifluoro-2-chloroethyl)diethylamine with trimethylsilyl isocyanate gives an adduct (1:2), which in reactions with nucleophilic reagents containing an active hydrogen atom gives derivatives of 2-chloro-2-fluoro-1-(diethylamino)ethylidenecarbamic acid.
- Gertsyuk, M. N.,Dronkina, M. I.,Samarai, L. I.
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p. 1228 - 1231
(2007/10/02)
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- Chemical process
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Optionally substituted silicon isocyanates are prepared by reacting a corresponding silicon halide with an alkali metal cyanate or an alkaline earth metal cyanate in an inert solvent having a dielectric constant below about 10, in the presence of a crown ether as a catalyst.
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