- Formation of Aromatic O-Silylcarbamates from Aminosilanes and Their Subsequent Thermal Decomposition with Formation of Isocyanates
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A novel phosgene-free route to different isocyanates starts from CO2 and aminosilanes (cf. silylamines) to form so-called carbamoyloxysilanes (O-silylcarbamates), i. e., compounds with the general motif R1R2N?CO?O?SiR3R4R5 as potential precursors. We focused on the insertion reaction of CO2 into Si?N bonds of substrates with cyclic (mostly aromatic) amine substituents, i. e., PhNHSiMe3, (PhNH)2SiMe2, PhCH2NHSiMe3, p-(MeO)C6H4NHSiMe3, o-C6H4(NHSiMe3)2, 1,2-C6H10(NHSiMe3)2, o-C6H4(NHSiMe3)(CH2NHSiMe3) and 1,8-C10H6(NHSiMe3)2. Compared to previously investigated aminosilanes these reactions are hindered due to the reduced nucleophilicity/basicity of the N-atoms. Whereas slightly increased CO2 pressure (8 bar) and prolonged reaction times (24 h) were sufficient to overcome hindrance of the insertion into, e. g., PhNHSiMe3, intermolecular effects in some two-fold NHSiMe3 functionalized substrates led to partial mono-insertion (e. g., into o-C6H4(NHSiMe3)(CH2NHSiMe3)) or intra-molecular condensation of the intermediate insertion product in case of 1,8-C10H6(NHSiMe3)2 to form 1H-perimidin-2(3H)-one and other side products. Thermal treatment of mono-silylated O-silylcarbamates RHN?CO?O?SiR’3 resulted mainly in the formation of substituted ureas (RHN)2CO, whereas desired isocyanates could not be detected in these cases. Therefore, we continued our studies focussing on N,O-bissilylated precursors, which were obtained by an additional N-silylation of the O-silylated carbamates. This allowed the successful formation of isocyanates. As a sole byproduct hexamethyldisiloxane is formed. In all cases, known as well as yet unknown substances were characterised by 1H, 13C and 29Si NMR spectroscopy, along with X-ray diffraction analysis for crystallized solids.
- Gründler, Franziska,Herbig, Marcus,Kroke, Edwin,Scholz, Henrik,Schwarzer, Sandra,Wagler, J?rg
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p. 2211 - 2224
(2021/06/11)
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- A simple and efficient room temperature silylation of diverse functional groups with hexamethyldisilazane using CeO2 nanoparticles as solid catalysts
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In this study, a mild and efficient method is developed for the silylation of diverse functional groups using CeO2 nanoparticles (n-CeO2) as solid catalysts with hexamethyldisilazane (HMDS) as silylating agent at room temperature. Alcohols, phenols and acids are silylated to their respective silyl derivatives with faster reaction rate while amines and thiols required relatively longer reaction time. Moreover, the solid catalyst is easily be separated from the reaction mixture and recycled more than five times without any obvious decay in its activity. Powder X-ray diffraction (XRD), transmission electron microscope (TEM), UV–vis diffuse reflectance spectra (UV-DRS) and Raman analyses revealed identical structural integrity, particle size, absorption edge and valence state for the reused solid compared to the fresh solid catalyst.
- Anbu, Nagaraj,Vijayan, Chellappa,Dhakshinamoorthy, Amarajothi
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- Trimethylsilyl-Induced N-O Bond Cleavage in Nitrous Oxide-Derived Aminodiazotates
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The chemical activation of nitrous oxide (N2O) typically results in O-atom transfer and the extrusion of N2 gas. In contrast, reactions of N-trimethylsilyl (TMS)-substituted amides with N2O give inorganic or organic azides
- Liu, Yizhu,Eymann, Léonard Y. M.,Solari, Euro,Fadaei Tirani, Farzaneh,Scopelliti, Rosario,Severin, Kay
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p. 11859 - 11863
(2018/09/25)
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- Insertion of phenyl isocyanate into monoand diaminosilanes
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The aminosilanes MenSi(NRR')4-n (n = 2,3) with NRR' = ethylamino (NHEt), n-propylamino (NHnPr), sec-butylamino (NHsBu), n-octylamino (NHnOct), n-dodecylamino (NHnDodec), allylamino (NHAll), tert-butylamino (NHtBu), diethylamino (NEt2), and anilino (NHPh) were synthesized and their reactions with phenyl isocyanate were studied. In all cases of these silanes Me3SiNRR' and Me2Si(NRR')2 formal insertion of the -NCO group into their Si-N bonds was observed, i.e. formation of products with Si-N (rather than Si-O) bonds was found. In some cases, the products could be crystallized and their molecular structures have been elucidated with single-crystal X-ray diffraction analyses.
- Kraushaar, Konstantin,Herbig, Marcus,Schmidt, Dana,Wagler, J?rg,B?hme, Uwe,Kroke, Edwin
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p. 909 - 921
(2018/01/19)
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- Ruthenium-catalyzed dealkenative N-silylation of amines by substituted vinylsilanes
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The ruthenium hydride complex-catalyzed N-silylation of primary and secondary amines with substituted vinylsilanes, with the general formula R1CHCHSiR′3 (where R1 = H, Ph, n-Bu, Si(OEt)3), leading to the formation of a Si-
- Marciniec, Bogdan,Kostera, Sylwia,Wyrzykiewicz, Bozena,Pawlu, Piotr
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supporting information
p. 782 - 786
(2015/02/19)
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- Synthesis of 1,3-dichloro- cyclo -1,3-diphosphadiazanes from silylated amino(dichloro)phosphanes
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The synthesis of 1,3-dichloro-cyclo-1,3-diphosphadiazanes [ClP(μ-NR)]2 via elimination of Me3SiCl from silylated amino(dichloro)phosphanes, R-N(SiMe3)PCl2, was studied by different synthetic protocols starting from R-N(H)SiMe3 (R = Si(SiMe3)3 = Hyp, N(SiMe3)2, Mes* = 2,4,6-tri-tert-butylphenyl, Ter = 2,4-bis(2,4,6-trimethylphenyl) phenyl, Dipp = 2,6-diisopropylphenyl, Dmp =2,6-dimethylphenyl, Ad = Adamantyl, Trityl = Ph3C, Tos = tosyl = CH3C6H 4SO2, n-Oct = n-octyl, and Me3Si). A new synthetic route using trimethylsilyl-substituted amino(dichloro)phosphanes, R-N(SiMe3)PCl2, was developed to form cyclo-diphosph(III)- azanes simply by adding a mixture of RfOH/base (RfOH = hexafluoroisopropanole). By this method electron-rich/-poor aryl-, silyl-, and bissilylamino-substituted cyclo-diphosph(III)-azanes are accessible such as the unprecedented (Me3Si)2N-substituted species [ClP(μ-NN(SiMe3)2)]2 starting from tris(trimethylsilyl)hydrazine and PCl3. Additionally, the difficulties with the preparation of cyclo-diphosphadiazanes depending on the starting materials, solvents, and bases due to the competition of different reaction channels are studied.
- Schulz, Axel,Villinger, Alexander,Westenkirchner, Andrea
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supporting information
p. 11457 - 11468
(2013/10/22)
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- A highly facile approach to the synthesis of novel 2-(3-benzyl-2,4-dioxo-1, 2,3,4-tetrahydropyrimidin-1-yl)-N-phenylacetamides
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A series of heterocyclic compounds were designed as potential nonnucleoside HIV reverse transcriptase inhibitors. Although the compounds ultimately proved inactive against HIV, during the course of the synthesis, a new and highly facile method to realize N-phenylacetamides was developed. Notably, the new route avoids the intractable workups and byproducts previously reported procedures have been associated with, thereby making this approach highly attractive to adaptation with other heterocyclics.
- Novikov, Mikhail S.,Babkov, Denis A.,Paramonova, Maria P.,Chizhov, Alexander O.,Khandazhinskaya, Anastasia L.,Seley-Radtke, Katherine L.
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supporting information
p. 576 - 578
(2013/02/23)
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- Iron-catalyzed aromatic amination for nonsymmetrical triarylamine synthesis
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Novel iron-catalyzed amination reactions of various aryl bromides have been developed for the synthesis of diaryl- and triarylamines. The key to the success of this protocol is the use of in situ generated magnesium amides in the presence of a lithium halide, which dramatically increases the product yield. The present method is simple and free of precious and expensive metals and ligands, thus providing a facile route to triarylamines, a recurrent core unit in organic electronic materials as well as pharmaceuticals.
- Hatakeyama, Takuji,Imayoshi, Ryuji,Yoshimoto, Yuya,Ghorai, Sujit K.,Jin, Masayoshi,Takaya, Hikaru,Norisuye, Kazuhiro,Sohrin, Yoshiki,Nakamura, Masaharu
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supporting information
p. 20262 - 20265
(2013/02/23)
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- Cu(NO3)2 · 3 H2O as an efficient reagent for the chemoselective trimethylsilylation of primary alcohols and oxidation of trimethylsilyl ethers
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Cu(NO3)2 · 3 H2O can be used as an efficient reagent for the chemoselective trimethylsilylation of primary benzylic and aliphatic alcohols with hexamethyldisilazane (HMDS). This reagent is also able to oxidize the obtained trimethylsilyl ethers to the corresponding carbonyl compounds in the presence of wet SiO2 and KBr. In this study, all reactions are performed in the absence of a solvent and good-to-high yields are obtained.
- Shirini,Mashhadi-Nejad
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experimental part
p. 376 - 381
(2012/04/04)
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- N-bonded monosilanols: Synthesis and characterization of ArN(SiMe 3) SiMe2Cl and ArN(SiMe3)SiMe2OH (Ar = C6H5, 2,6-Me2C6H3, 2,6-iPr2C6H3)
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By the use of aniline and the sterically hindered aromatic primary amines, 2,6-Me2C6H3NH2 and 2,6-iPr 2C6H3NH2, N-bonded monochlorosilanes, ArN(SiMe3)SiMe2Cl [Ar = C 6H5 (1a), Ar = 2,6-Me2C6H 3 (1b) and Ar = 2,6-iPr2C6H3 (1c)] have been prepared by a sequential deprotonation at the nitrogen followed by reaction with silyl chlorides. Hydrolysis of the N-bonded monochlorosilanes afforded the N-bonded monosilanols ArN(SiMe3)SiMe2OH [Ar = C6H5 (2a), Ar = 2,6-Me2C6H 3 (2b) and Ar = 2,6-iPr2C6H3 (2c)]. The X-ray crystal structure of le reveals a positional disorder of the Cl and CH3 substituents on silicon. The X-ray crystal structure of 2c shows that it is involved in an intermolecular O-H...O hydrogen bonding in the solid state to afford a dimeric structure containing the O2H 2 ring. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Chandrasekhar, Vadapalli,Boomishankar, Ramamoorthy,Azhakar, Ramachandran,Gopal, Kandasamy,Steiner, Alexander,Zacchini, Stefano
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p. 1880 - 1885
(2007/10/03)
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- Methods for preparation of 1,2-dihydroquinolines
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Methods for conversion of anilines to 1,2-dihydroquinolines. 1,2-dihydroquinoliiies are generated from combining an aniline, a silylating agent, and further condensing with a ketone in the presence of a catalyst. In one aspect, the silylation of the aniline may be performed in a one-step synthesis by adding the silylating, agent to the same reaction vessel as the ketone, aniline, and catalyst. In a second aspect, the 1,2-dihydroquinoline is generated in a two-step synthesis where an N-silyl aniline is formed prior to the addition of the ketone and catalyst.
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- Novel method for preparing bis(trimethylsilyl) amines via treatment with trimethylsilylamines and methyl iodide
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A convenient method for the synthesis of N,N-bis(trimethylsilyl)alkylamines has been reported. N-(Trimethylsilyl)diethylamine incorporated with a stoichiometric amount of methyl iodide was effective to convert primary amines, especially aromatic amines, and their monotrimethylsilyl derivatives into the corresponding N,N-bis(trimethylsilyl)amine derivatives in high yields. In the case of N-trimethylsilyl derivatives of aliphatic primary amines, a half-amount of silylamines served as a silylation agent against another half-amount of silylamines in the presence of 0.5 equivalent of methyl iodide to give N,N-bis(trimethylsilyl)alkylamines in good yield. Allyl iodide, allyl bromide and benzyl bromide were also effective to promote the silylation activity of silylamines.
- Hamada, Yoshitaka,Yamamoto, Yasushi,Shimizu, Hideaki
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- Trimethylsilyl Nitronates Derived from 2-Substituted Nitroethanes in δ-Elimination Reactions
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Silylation of β-substituted nitroethanes XCH2CH2NO2 (X=Cl or OCOCH3) with conventional silylating agents yields corresponding trimethylsilyl nitronates which undergo δ-elimination of nitroethylene under the reaction conditions.Stable silyl nitronates containing one or two trimethylsilyl groups were isolated in the silylation of C6H5NHCH2CH2NO2. 1,3-Dipolar cycloaddition of the nitronates to methoxide ion results in formation of 5-methoxycarbonyl-3-phenylaminomethyl(or 3-N-trimethylsilylphenylaminomethyl)-3-trimethylsiloxyisoxazolidines.Thermolysis of the latter affords 5-methoxycarbonyl-2-isoxazoline.
- Ioffe, S. L.,Makarenkova, L. M.,Strelenko, Yu. A.,Tartakovskii, V. A.
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p. 1099 - 1103
(2007/10/03)
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- Electrophilic Amination of Higher Order Cuprates with N,O-Bis(trimethylsilyl)hydroxylamine
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In the reaction of higher order cyanocuprates with N,O-bis(trimethylsilyl)hydroxylamine delivery of the NHSiMe3 moiety to one of the anionic ligands in the cuprate takes place even in the absence of external bases according to an "electrophilic amination" protocol.Details of the methodology are given, and the reaction mechanism is analyzed in terms of interception by a mixed bis-metal cluster of a lithium N-silyl-N-siloxyamide, followed by intramolecular C-N coupling.This method is applicable to cyanocuprates bearing aromatic, heteroaromatic, and saturated aliphatic ligands.A number of 2-amino-substituted heterocycles, not easily accesible by normal routes, can be obtained with the aid of a stabilizing silylation at the nitrogen atom.
- Casarini, Antonella,Dembech, Pasquale,Lazzari, Dario,Marini, Elisabetta,Reginato, Gianna,et al.
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p. 5620 - 5623
(2007/10/02)
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- Generation of Thionitrosoarenes (ArN=S) from N-(Arylaminothio)phthalimides and in situ Trapping with Alkenes and Conjugated Dienes
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A series of N-(arylaminothio)phthalimide derivatives (7a-h) has been prepared by reaction of phthalimidesulphenyl chloride with the trimethylsilyl derivative of the appropriate arylamine.On treatment with triethylamine at room temperature, compounds (7) fragment to yield transient thionitroso species (8).Derivatives (8a-h) have been trapped in good yield as their Diels-Alder adducts with the following conjugated dienes: butadiene, 2.3-dimethylbutadiene, 1.4-diphenylbutadiene, (E,E)- and (E,Z)-hexa-2,4-diene, 1,1'-bicyclopentenyl (25) and 1,1'-bicyclohexenyl (26).The stereochemistry of the diene is retained in the adducts (19)-(24).Thionitrosoarene derivatives (8) also afford sulphenamide derivatives, e.g. (11) and (12)-(16), by ene addition to dimethylbutadiene, isobutene, and α-methylstyrene.N-Aryliminosulphur dichlorides (34) react with 2,3-dimethylbutadiene to yield 1,2-thiazine and sulphenamide products, probably by way of thionitrosoarene intermediates.
- Bryce, Martin R.,Taylor, Paul C.
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p. 3225 - 3235
(2007/10/02)
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- Reactivity of the Labile Silaethene Me2Si=C(SiMe3)2, Stored as Ph2C=NSiMe3 Adducts
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Silaethene Me2Si=C(SiMe3)2 (1), stored as Ph2C=NSiMe3 adducts and regenerated from the adducts at about 100 deg C as a reaction intermediate, combines with reactants a-b (e.g.HO-H, RO-H, RCOO-H, RS-H, RHN-H, Ph2CN-H, RO-SiR3, R2N-SiR3, Ph2CN-SiR3, Cl-GeR3, Cl-SnR3) with insertion into the a-b bond, with a=b (e.g.O=CPh2, Me3SiN=CPh2, CH2=CHOMe, cis-piperylene), a=b=c (e.g.RN=N=N, O=N=N), a=b-c=d (e.g. butadiene, isoprene, trans-piperylene, 2,3-dimethylbutadiene, cyclopentadiene, anthracene, benzophenone, N-trimethylsilylbenzophenoneimine) under -, - as well as -c ycloaddition and with a=b-c-H (e.g. propene, butenes, isoprene, 2,3-dimethylbutadiene, acetone) under ene reaction.According to relative reaction rates, insertion and -cycloadditions seem to proceed in two reaction steps, whereas -cycloadditions and ene reactions with organic dienes and enes obviously are one step reactions.For reactivities cf.Table I. - Key words: Silaethene Me2Si=C(SiMe3)2, Insertions, Cycloadditions, Relative Reactivities
- Wiberg, N.,Preiner, G.,Wagner, G.,Koepf, H.
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p. 1062 - 1074
(2007/10/02)
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- Insertion of Sulfur Trioxide into the N-Si bond of Anilinotrimethylsilane. An Improved Method for the Preparation of Free Phenylamidosulfuric Acid
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The reaction between anilinotrimethylsilane (1) and a variety of sulfonating agents has been studied.With SO3, 5, or a dioxane-sulfur trioxide complex a sulfur trioxide molecule was inserted selectively into the N-Si bond of 1 to yield trimethylsilyl phenylamidosulfate (2), which on treatment with acetic acid, trifluoroacetic acid, or methanol gave free phenylamidosulfuric acid (3).The reaction of 1 with ClSO3H afforded 3 directly, but the product was contaminated with slight amounts of anilinium hydrogensulfate and anilinium chloride.The reaction of 1 with 10 yielded a mixture containing dianilinium (4-sulfonatophenylamido)sulfate, 4-aminobenzenesulfonic acid, and ethyl phenylamidosulfate as major products (after desilylation).The reaction of 1 with 5 has been found to provide an improved method for preparing 3.
- Kanetani, Fujio,Okada, Eiji,Negoro, Kenji
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p. 2517 - 2520
(2007/10/02)
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- Indirect Nuclear Spin-Spin Coupling Constants of Nitrogen-15 to Silicon-29 in Silylamines
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The 15N-29Si spin-spin coupling constants in silylamines have been measured from 29Si satellites in their natural abundance 15N n.m.r. spectra in an INEPT sequence for accumulation of signals and interpreted in terms of Fermi-contact interaction; the sensitivity of 1J(15N-29Si) to d?-p? bonding was noted.
- Kupce, Eriks,Liepins, Edvards,Pudova, Olga,Lukevics, Edmunds
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p. 581 - 582
(2007/10/02)
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- Method of preparing silicon-nitrogen compounds
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A process for preparing a silicon-nitrogen compound of the formula (R3 Si)n NR'3-n or R2 Si(NR'2)2 or RSi(NR'2)3 or cyclic --R2 SiNR'--x wherein n is 1 or 2 or 3, R' is a hydrogen atom or an alkyl moiety of 1 to 8 carbon atoms or aryl moiety, R represents an alkyl moiety of 1 to 20 carbon atoms or aryl moiety and x is 3 or 4, by contacting a hydrogen silane of the formula R4-y SiHy where y is 1 or 2 or 3 and R has the above-described meaning with an ammonia or an amine of the formula NR'3-n Hn' where R' and n have the above meanings in the presence of a catalyst.
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