- Convergent Synthesis of Pyrrolidines, Piperidines, Perhydroazepines and Tetrahydroisoquinolines via Zirconocene η2-Imine Complexes
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Zirconocene η2-imine complexes formed by a C-H activation route from a variety of amines are trapped by ω-halo-alkenes or -alkynes to afford 2,3-disubstituted pyrrolidines, piperidines and perhydroazepines on work up and cyclisation.In some cas
- Harris, Michael C. J.,Whitby, Richard J.,Blagg, Julian
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- N-trimethylsilyl amines for controlled ring-opening polymerization of amino acid N-carboxyanhydrides and facile end group functionalization of polypeptides
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We report a new strategy that uses N-trimethylsilyl (N-TMS) amine to mediate controlled ring-opening polymerization of amino acid N-carboxyanhydrides (NCAs). This polymerization proceeds via a unique, trimethylsilyl carbamate (TMS-CBM) propagating group t
- Lu, Hua,Cheng, Jianjun
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- Latent Nucleophilic Carbenes
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Using DFT and ab initio calculations, we demonstrate that noncyclic formamidines can undergo thermal rearrangement into their isomeric aminocarbenes under rather mild conditions. We synthesized the silylformamidine, for which the lowest activation energy in this process was predicted. Experimental studies proved it to serve as a very reactive nucleophilic carbene. The reactions with acetylenes, benzenes, and trifluoromethane proceeded via insertion into sp, sp2, and spCH bonds. The carbene also reacted with the functional groups, such as CHO, COR, and CN at double or triple bonds, displaying high mobility of the trimethylsilyl group. The obtained silylformamidine can be considered as a latent nucleophilic carbene. It can be prepared in bulk quantities, stored, and used when the need arises. Calculation results predict similar behavior for some other silylated formamidines and related compounds.
- Marchenko, Anatoliy,Koidan, Georgyi,Hurieva, Anastasiya,Shvydenko, Kostiantyn,Rozhenko, Alexander B.,Rusanov, Eduard B.,Kyrylchuk, Andrii A.,Kostyuk, Aleksandr
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p. 373 - 385
(2021/12/27)
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- Hypervalent Iodine(III) Reagents with Transferable Primary Amines: Structure and Reactivity on the Electrophilic α-Amination of Stabilized Enolates
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A new family of hypervalent iodine reagents containing transferable primary amine groups is described. Benziodoxolone-based reagents were synthesized on the gram-scale through operationally simple reactions in up to quantitative yields. These bench-stable solids were characterized by X-ray analysis and successfully employed in the α-amination of indanone-based β-ketoesters in up to 83% yield. Mechanistic studies indicate a substitution mechanism involving an electrophilic amine.
- Poeira, Diogo L.,Negr?o, Ana Cláudia R.,Faustino, Hélio,Coelho, Jaime A. S.,Gomes, Clara S. B.,Gois, Pedro M. P.,Marques, M. Manuel B.
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supporting information
p. 776 - 781
(2022/01/20)
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- 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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- Nickel-Catalyzed Decarbonylative Amination of Carboxylic Acid Esters
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The reaction of carboxylic acid derivatives with amines to form amide bonds has been the most widely used transformation in organic synthesis over the past century. Its utility is driven by the broad availability of the starting materials as well as the kinetic and thermodynamic driving force for amide bond formation. As such, the invention of new reactions between carboxylic acid derivatives and amines that strategically deviate from amide bond formation remains both a challenge and an opportunity for synthetic chemists. This report describes the development of a nickel-catalyzed decarbonylative reaction that couples (hetero)aromatic esters with a broad scope of amines to form (hetero)aryl amine products. The successful realization of this transformation was predicated on strategic design of the cross-coupling partners (phenol esters and silyl amines) to preclude conventional reactivity that forms inert amide byproducts.
- Malapit, Christian A.,Borrell, Margarida,Milbauer, Michael W.,Brigham, Conor E.,Sanford, Melanie S.
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supporting information
p. 5918 - 5923
(2020/04/08)
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- Zirconium Hydroaminoalkylation. An Alternative Disconnection for the Catalytic Synthesis of α-Arylated Primary Amines
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Primary amine products have been prepared using zirconium-catalyzed hydroaminoalkylation of alkenes with N-silylated benzylamine substrates. Catalysis using commercially available Zr(NMe2)4 affords an alternative disconnection to acc
- Koperniku, Ana,Foth, Paul J.,Sammis, Glenn M.,Schafer, Laurel L.
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supporting information
p. 18944 - 18948
(2019/12/04)
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- Sequential Barium-Catalysed N?H/H?Si Dehydrogenative Cross-Couplings: Cyclodisilazanes versus Linear Oligosilazanes
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Starting from Ph3SiH, the barium precatalyst Ba[CH(SiMe3)2]2?(THF)3was used to produce the disilazane Ph3SiN(Bn)SiPh2NHBn (4) by sequential N?H/H?Si dehydrogenative couplings with BnNH2and Ph2SiH2. Substrate scope was extended to other amines and hydrosilanes. This smooth protocol gives quantitative yields and full chemoselectivity. Compound 4 and the intermediates Ph3SiNHBn and Ph3SiN(Bn)SiHPh2were structurally characterised. Further attempts at chain extension by dehydrocoupling of Ph2SiH2with 4 instead resulted in cyclisation of this compound, forming the cyclodisilazane c-(Ph2Si-NBn)2(5) which was crystallographically authenticated. The ring-closure mechanism leading to 5 upon release of C6H6was determined by complementary experimental and theoretical (DFT) investigations. Ba[CH(SiMe3)2]2?(THF)3and 4 react to afford the reactive Ba{N(Bn)SiPh2N(Bn)SiPh3}2, which was characterised in situ by NMR spectroscopy. Next, in a stepwise process, intramolecular nucleophilic attack of the metal-bound amide on the terminal silicon atom generates a five-coordinate silicate. It is followed by turnover-limiting β-C6H5transfer to barium; this releases 5 and forms a transient [Ba]?Ph species, which undergoes aminolysis to regenerate [Ba]?N(Bn)SiPh2N(Bn)SiPh3. DFT computations reveal that the irreversible production of 5 through such a stepwise ring-closure mechanism is much more kinetically facile (ΔG≠=26.2 kcal mol?1) than an alternative σ-metathesis pathway (ΔG≠=48.2 kcal mol?1).
- Bellini, Clément,Roisnel, Thierry,Carpentier, Jean-Fran?ois,Tobisch, Sven,Sarazin, Yann
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supporting information
p. 15733 - 15743
(2016/10/25)
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- Tridentate P,N,N-ligand promoted copper-catalyzed [3 + 2] cycloaddition of propargylic esters with β-enamino esters: Synthesis of highly functionalized pyrroles
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A copper-catalyzed [3 + 2] cycloaddition of propargylic esters with β-enamino esters under mild reaction conditions for the construction of highly functionalized pyrroles has been developed. By employment of a newly developed tridentate P,N,N-ligand, a va
- Li, Qing,Hou, Chuan-Jin,Hui, Yun-Ze,Liu, Yan-Jun,Yang, Rui-Feng,Hu, Xiang-Ping
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p. 85879 - 85883
(2015/11/03)
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- Consecutive oxygen-based oxidations convert amines to α-cyanoepoxides
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Tri- or tetrasubstituted α-cyanoepoxides can be rapidly prepared from unactivated amines and malononitrile or methyl cyanoacetate when singlet oxygen, produced in a continuous-flow photoreactor, serves as an oxidant and in situ peroxide source. The hydrogen peroxide generated in amine oxidation epoxidizes an electron deficient olefin intermediate, formed by deaminative Mannich coupling. The corresponding α,α-dicyano- or α-cyano-α-esterepoxides were obtained in good yields (43-82%). This journal is
- Ushakov, Dmitry B.,Gilmore, Kerry,Seeberger, Peter H.
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supporting information
p. 12649 - 12651
(2015/05/20)
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- Imine hydrogenation by alkylaluminum catalysts
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Di-isobutylaluminum hydride and tri-iso-butylaluminum (DIBAL 1, TIBAL 2) are shown to be efficient hydrogenation catalysts for a variety of imines at 100 °C and 100 atm of H2, operating via a hydroalumination/ hydrogenolysis mechanism.
- Hatnean, Jillian A.,Thomson, Jordan W.,Chase, Preston A.,Stephan, Douglas W.
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supporting information
p. 301 - 303
(2014/01/06)
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- H2 cleavage, hydride formation, and catalytic hydrogenation of imines with zinc complexes of C5Me5 and N-heterocyclic carbenes
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Decamethylzincocene, [ZnCp2], reacts with H2 to give the reduced ZnI compound [Zn2Cp2]. In the presence of coordinating and (more efficiently) of non-coordinating N-heterocyclic carbenes (NHCs), the catalytic hydrogenation of imines with H2 is achieved. The monomeric hydride [Zn(Cp)(H)(SIMes)] is presented and its mechanistic implications are considered. Copyright
- Jochmann, Phillip,Stephan, Douglas W.
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supporting information
p. 9831 - 9835
(2013/09/23)
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- Organosilicon synthesis of isocyanates: II. Synthesis of aliphatic, carbocyclic, and fatty-aromatic isocyanates
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Silylation of a series of aliphatic, carbocyclic, and fatty-aromatic amines gave the corresponding silyl derivatives whose yield depended on the electronic and steric structure of the substrate and the nature of the silylating agent. The yield of isocyanates obtained by phosgenation of the silyl derivatives under mild conditions decreased in going from aliphatic amines to benzylamines and rose as the length of the alkyl chain in fatty-aromatic amines extended. The most convenient procedure for the synthesis of low-boiling alkyl isocyanates was found to be based on the transformation of amines or ammonium salts into silyl or silyl silyl-carabamates, followed by pyrolysis of the latter in the presence of trichloro(phenyl)silane. Pleiades Publishing, Inc., 2006.
- Lebedev,Lebedeva,Sheludyakov,Ovcharuk,Kovaleva,Ustinova
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p. 469 - 477
(2008/02/07)
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- Organolanthanide-catalyzed imine hydrogenation. Scope, selectivity, mechanistic observations, and unusual byproducts
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In this paper we report the Cp'2LnMe2SiCp''2Ln-catalyzed (Cp' = η5-Me5C5; Cp'' = η5-Me4C5) hydrogenation of acyclic imines to yield the corresponding amines. At 190 psi of H2, the observed turnover frequencies (h-1) (100:1 substrate:catalyst ratio, Cp'2Ln, temperature (°C)) are (1) (N-benzylidene(methyl)amine, Ln = La, 50) 0.03; (Ln = Sm, 90) 1.0; (Ln = Sm + PhSiH3, 90) 2.2; (Ln = Lu, 90) 0.60; (2) (N-benzylideneaniline, Ln = Sm, 90) 0.10; (3) (N-benzylidene(trimethylsilyl)amine, Ln = Sm, 90) 0.40; (4) (N-(α-methylbenzylidene)(methyl)amine, Ln = Sm, 90) 0.20; (5) (N-(α-methylbenzylidene)(benzyl)amine, Ln = Sm, 90) 0.70. The stoichiometric reaction of N-benzylidene(methyl)amine with Cp'2SmCH(SiMe3)2 or (Cp'2SmH)2 yields an orthometalated Cp'2Sm-substrate complex which undergoes either hydrogenolysis/hydrogenation or competing C=N insertion of a second substrate molecule to yield a Cp'2Sm-imine-amido complex with a seven-membered chelate ring. The stoichiometric reaction of 2-methyl-1-pyrroline with Cp'2SmCH(SiMe3)2 or (Cp'2SmH)2 yields a Cp'2Sm-imine-amido complex in which two substrate molecules have been coupled to form a six-membered chelate ring (characterized by X-ray diffraction). The stoichiometric reaction of N-benzylidene(trimethylsilyl)amine with (Cp'2SmH)2 yields a desilylated Cp'2Sm-imine-amido complex with a four-membered Sm(NSiMe3)(CPh)N=CHPh chelate ring (characterized by X-ray diffraction). Additional heating of this product under H2 yields S6-symmetric (Cp'2SmCN)6, which contains an unusual chairlike 18-membered (SmCN)6 ring (characterized by X-ray diffraction).
- Obora, Yasushi,Ohta, Tetsuo,Stern, Charlotte L.,Marks, Tobin J.
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p. 3745 - 3755
(2007/10/03)
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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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- Co2(CO)8-Catalyzed Ring-Opening Carbonylation of Cyclic Ethers Using N-Silylamines
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Co2(CO)8-catalyzed ring-opening carbonylation of oxiranes and oxetane smoothly proceeds with high regioselectivity under 1 atm of carbon monoxide at room temperature to give the corresponding β- and γ-siloxy amides in high yields, respectively. 1R2>+- is thought to be an active catalyst species and directs the high regioselectivity of the carbonylation.
- Watanabe, Yoshihisa,Nishiyama, Kazuhiro,Zhang, Kunsan,Okuda, Fumio,Kondo, Teruyuki,Tsuji, Yasushi
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p. 879 - 882
(2007/10/02)
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- REGIO- AND CHEMOSELECTIVE N-C BOND FORMATION VIA CARBON DIOXIDE: A NEW SOURCE OF THE METHYL GROUP, APPLICATIONS TO N-METHYLATED SECONDARY AND TERTIARY AMINES
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Reductive carboxylation of a variety of secondary and primary amines to the corresponding N-methylated amines in the presence of various functional groups such as chlorosubstituents, carbon-carbon double bonds and phenolic hydroxyls is described.
- Ram, Siya,Spicer, Leonard D.
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p. 3561 - 3572
(2007/10/02)
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- ALKYLATION OF N-TRIMETHYLSILYLATED PRIMARY AMINES WITH ARYLETHYLENE OXIDES. AN EFFICIENT SYNTHESIS OF 1-PHENETHANOLAMINES.
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Reaction of unhindered N-trimethylsilylated primary amines with styrene oxide derivatives provides good yields of 1-phenethanolamines after acidic hydrolysis during work-up.This methodology results in much better conversions and higher yields when compare
- Atkins, Randall K.,Frazier, Jeffery,Moore, Larry L.,Weigel, Leland O.
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p. 2451 - 2454
(2007/10/02)
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- Silicon-Nitrogen Bonds. XXXIX. Kinetic Studies on the Spontaneous Hydrolysis, Alcoholysis, and Phenolysis of Silylamines
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It could be shown by polarimetric and DC-metric methods that hydrolysis, alcoholysis, and phenolysis of silylamines are of second order and lead to equilibria.The rate of equilibrium establishment is determined by the position of a preceding protonation equilibrium and by steric effects.The position of the equilibria depends on inductive and steric effects.The enthalpy of activation for the ethanolysis of Me3SiNHPh was determined to 27,2 kJ/mol and the entropy of activation to -231 J/K*mol.The mechanism of the reactions is given.
- Kaufmann, K.-D.,Gisbier, D.,Grosse-Ruyken, H.,Ruehlmann, K.
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p. 721 - 728
(2007/10/02)
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