3378-71-0Relevant articles and documents
An improved reduction procedure in the synthesis of substituted pyrrolidines via an aminomercuration/reduction sequence of primary alkenylamines
Roubaud, Valerie,Le Moigne, Francois,Mercier, Anne,Tordo, Paul
, p. 1507 - 1516 (1996)
Aminomercuration/reduction sequence of δ-alkenylamines is a typical route to substituted pyrrolidines. Backward reaction to the starting material is a major drawback which occurs during sodium borohydride reduction of the intermediate organomercurial. We describe here a new reduction procedure which prevents almost completely this backward reaction and leads to significant increases in the yields of pyrrolidines.
Thermal Behavior Analysis of Two Synthesized Flavor Precursors of N-alkylpyrrole Derivatives
Ai, Lvye,Liu, Mengzhen,Ji, Xiaoming,Lai, Miao,Zhao, Mingqin,Ren, Tianbao
, p. 2389 - 2397 (2019/08/01)
To expand the library of pyrrole-containing flavor precursors, two new flavor precursors—methyl N-benzyl-2-methyl-5-formylpyrrole-3-carboxylate (NBMF) and methyl N-butyl-2-methyl-5-formylpyrrole-3-carboxylate (NUMF)—were synthesized by cyclization, oxidation, and alkylation reactions. Thermogravimetry (TG), differential scanning calorimeter, and pyrolysis–gas chromatography/mass spectrometry were utilized to analyze the thermal degradation behavior and thermal degradation products of NBMF and NUMF. The TG-DTG curve indicated that the maximum mass loss rates of NBMF and NUMF appear at 310 and 268°C, respectively. The largest peaks of NBMF and NUMF showed by the differential scanning calorimeter curve were 315 and 274°C, respectively. Pyrolysis–gas chromatography/mass spectrometry detected small molecule fragrance compounds appeared during thermal degradation, such as 2-methylpyrrole, 1-methylpyrrole-2-carboxylic acid methyl ester, limonene, and methyl formate. Finally, the thermal degradation mechanism of NBMF and NUMF was discussed, which provided a theoretical basis for their application in tobacco flavoring additives.
Reactivity of functionalized indoles with rare-earth metal amides. Synthesis, characterization and catalytic activity of rare-earth metal complexes incorporating indolyl ligands
Feng, Zhijun,Wei, Yun,Zhou, Shuangliu,Zhang, Guangchao,Zhu, Xiancui,Guo, Liping,Wang, Shaowu,Mu, Xiaolong
, p. 20502 - 20513 (2015/12/05)
The reactivity of several functionalized indoles 2-(RNHCH2)C8H5NH (R = C6H5 (1), tBu (2), 2,6-iPr2C6H3 (3)) with rare-earth metal amides is described. Reactions of 1 or 2 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 (RE = Eu, Yb) respectively produced the europium complexes [2-(C6H5NCH)C8H5N]2Eu[N(SiMe3)2] (4) and [2-(tBuNCH)C8H5N]Eu[N(SiMe3)2]2 (5), and the ytterbium complex [2-(tBuNCH)C8H5N]2Yb[N(SiMe3)2] (6), containing bidentate anionic indolyl ligands via dehydrogenation of the amine to the imine. In contrast, reactions of the more sterically bulky indole 3 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 afforded complexes [2-(2,6-iPr2C6H3NCH2)C8H5N]RE[N(SiMe3)2](THF)2 (RE = Yb (7), Y (8), Er (9), Dy (10)) with the deprotonated indolyl ligand. While reactions of 3 with yttrium and ytterbium amides in refluxing toluene respectively gave the complexes [2-(2,6-iPr2C6H3NCH)C8H5N]3Y (11) and [2-(2,6-iPr2C6H3NCH)C8H5N]2YbII(THF)2 (12), along with transformation of the amino group to the imino group, and also with a reduction of Yb3+ to Yb2+ in the formation of 12. Reactions of 3 with samarium and neodymium amides provided novel dinuclear complexes {[μ-η5:η1:η1-2-(2,6-iPr2C6H3NCH2)C8H5N]RE[N(SiMe3)2]}2 (RE = Sm (13), Nd (14)) having indolyl ligands in μ-η5:η1:η1 hapticities. The pathway for the transformation of the amino group to the imino group is proposed on the basis of the experimental results. The new complexes displayed excellent activity in the intramolecular hydroamination of aminoalkenes.
Bis(imidazolin-2-iminato) rare earth metal complexes: Synthesis, structural characterization, and catalytic application
Trambitas, Alexandra G.,Melcher, Daniel,Hartenstein, Larissa,Roesky, Peter W.,Daniliuc, Constantin,Jones, Peter G.,Tamm, Matthias
experimental part, p. 6753 - 6761 (2012/08/07)
Reaction of anhydrous rare earth metal halides MCl3 with 2 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (ImDippNH) and 2 equiv of trimethylsilylmethyl lithium (Me3SiCH2Li) in THF furnished the complexes [(ImDippN)2MCl(THF)n] (M = Sc, Y, Lu). The molecular structures of all three compounds were established by single-crystal X-ray diffraction analyses. The coordination spheres around the pentacoordinate metal atoms are best described as trigonal bipyramids. Reaction of YbI2 with 2 equiv of LiCH 2SiMe3 and 2 equiv of the imino ligand ImDippNH in tetrahydrofuran did not result in a divalent complex, but instead the Yb(III) complex [(ImDippN)2YbI(THF)2] was obtained and structurally characterized. Treatment of [(ImDippN) 2MCl(THF)n] with 1 equiv of LiCH2SiMe 3 resulted in the formation of [(ImDippN) 2M(CH2SiMe3)(THF)n]. The coordination arrangement of these compounds in the solid state at the metal atoms is similar to that found for the starting materials, although the introduction of the neosilyl ligand induces a significantly greater distortion from the ideal trigonal-bipyramidal geometry. [(ImDippN) 2Y(CH2SiMe3)(THF)2] was used as precatalyst in the intramolecular hydroamination/cyclization reaction of various terminal aminoalkenes and of one aminoalkyne. The complex showed high catalytic activity and selectivity. A comparison with the previously reported dialkyl yttrium complex [(ImDippN)Y(CH2SiMe3) 2(THF)3] showed no clear tendency in terms of activity.
2,5-Bis{ N -(2,6-diisopropylphenyl)iminomethyl}pyrrolyl complexes of the heavy alkaline earth metals: Synthesis, structures, and hydroamination catalysis
Jenter, Jelena,Koeppe, Ralf,Roesky, Peter W.
experimental part, p. 1404 - 1413 (2011/04/25)
The heteroleptic iodo complexes [(DIP2pyr)MI(THF)n] (M = Ca, Sr (n = 3); Ba (n = 4); (DIP2pyr)- = 2,5-bis{N-(2,6-diisopropylphenyl)iminomethyl}pyrrolyl) were synthesized by reaction of [(DIP2pyr)K] with anhydrous alkaline earth metal diiodides. All complexes are monomeric in the solid state. A κ3-coordination mode of the (DIP2pyr)- ligand was observed for the strontium and the barium compounds, while the analogous calcium derivative is κ2-coordinated in the solid state. However, VT-1H NMR studies of [(DIP2pyr)CaI(THF) 3] indicate a symmetrically coordinated (DIP2pyr) - ligand in solution. Computational studies confirm the different coordination modes in solution and in the solid state. The preferred κ2-coordination mode observed in the solid state might be a result of temperature or/and crystal-packing effects. Furthermore, the calcium and strontium amido complexes [(DIP2pyr)M{N(SiMe3) 2}(THF)2] (M = Ca, Sr) were prepared by reaction of [(DIP2pyr)MI(THF)n] (M = Ca, Sr (n = 3)) with [K{N(SiMe3)2}]. Both compounds were investigated for the intramolecular hydroamination of aminoalkenes. Both catalysts showed a good activity, and the best results were obtained for the calcium complex [(DIP 2pyr)Ca{N(SiMe3)2}(THF)2].
Highly active and diastereoselective N,O- and N,N-yttrium complexes for intramolecular hydroamination
Lauterwasser, Frank,Hayes, Paul G.,Piers, Warren E.,Schafer, Laurel L.,Braese, Stefan
experimental part, p. 1384 - 1390 (2011/06/26)
The intramolecular hydroamination of aminoalkynes and unactivated aminoalkenes catalyzed by yttrium N,O- and N,N-complexes has been investigated. The N,N-yttrium complexes are highly active, catalyzing the conversion of a wide range of terminal aminoalkenes at room temperature, and internal aminoalkenes at elevated temperature, to yield pyrrolidine and piperidine products in high yields. A high diastereoselectivity of up to 23:1 is observed at 0°C with 1-methyl-4-pentenylamine as substrate.
Zirconium bis(pyridonate): A modified amidate complex for enhanced substrate scope in aminoalkene cyclohydroamination
Bexrud, Jason A.,Schafer, Laurel L.
supporting information; experimental part, p. 361 - 363 (2010/04/03)
A new bis(amidate)zirconium bis(amido) hydroamination pre-catalyst using 6-tert-butyl-3-phenyl-2-pyridone as a proligand has been prepared and characterized. This rare example of an early transition metal complex incorporating a 2-pyridonate derivative as an ancillary ligand was found to be effective for the cyclohydroamination of aminoalkenes, including more challenging substrates bearing unactivated internal CC bonds. The Royal Society of Chemistry.
Rare-earth metal alkyl, amido, and cyclopentadienyl complexes supported by Lmidazolin-2-iminato ligands: Synthesis, structural characterization, and catalytic application
Trambitas, Alexandra G.,Panda, Tarun K.,Jenter, Jelena,Roesky, Peter W.,Daniliuc, Constantin,Hrib, Cristian G.,Jones, Peter G.,Tamm, Matthias
experimental part, p. 2435 - 2446 (2010/05/15)
The rare earth metal dichlorides [(1)MCl2(THF)3] (2a, M = Sc; 2b, M = Y; 2c, M = Lu) and the gadolinium complex [(1)GdCl 2(THF)2]·[LiCl(THF)2] (2d), containing the 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-iminato ligand 1, proved to be versatile starting materials for the preparation of trimethylsilylmethyl ("neosilyl") and bis(thmethylsilyl)amido complexes [(1)M(CH 2SiMe3)2(THF)2] (3a-3d) and [(1)M(HMDS)2(THF)] [4a-4d, HMDS = hexamethyldisilazide, N(SiMe 3)2] and for the preparation of the benzyl complex [(1)Lu(CH2Ph)2(THF)2] (5c) by the reaction with LiCH2SiMe3, Na[N(SiMe3)2], and KCH2Ph, respectively. Treatment of 2a-2c with KCp* afforded the mono(pentamethylcyclopentadienyl) complexes [(1)Sc(Cp*)Cl(THF)] (6a), [(1)Y(Cp*)Cl(THF)2] (6b), and [(1)Lu(Cp*)Cl(THF)] (6c). In contrast, the gadolinocene complex [(1)Gd(Cp*)2(THF)] (7) was isolated from the reaction of 2d with 2 equiv of KCp*. The molecular structures of 3a-3d, 4b-THF, 4d, 5c, 6a, 6c, and 7-THF were determined by X-ray diffraction analyses, revealing the presence of exceptionally short metal-nitrogen bonds. The neosilyl complexes 3b and 3c showed high catalytic activity in the intramolecular hydroamination of aminoalkenes and aminoalkynes and in the hydrosilylation of 1-hexene and 1-octene with PhSiH3.
C2-symmetric zirconium Bis(Amidate) complexes with enhanced reactivity in aminoalkene hydroamination
Reznichenko, Alexander L.,Hultzsch, Kai C.
scheme or table, p. 24 - 27 (2010/03/04)
Binaphthalenedicarboxamide zirconium complexes exhibit significantly enhanced catalytic activity in aminoalkene hydroamination reactions with respect to substrate scope (substrates without gem-dialkyl activation; cyclization of aminoheptenes), catalyst loading (as low as 0.5 mol %) and reaction temperatures (as low as 70 °C) compared to previous group 4 metal-based hydroamination catalyst systems.
Kinetic resolution of aminoalkenes by asymmetric hydroamination: A mechanistic study
Reznichenko, Alexander L.,Hampel, Frank,Hultzsch, Kai C.
scheme or table, p. 12819 - 12827 (2010/06/17)
The kinetic resolution of chiral aminoalkenes by hydroamination-cyclization was studied by using 3,3'-bis(triarylsilyl)-substituted binaphtholate rare-earth-metal complexes. The resolution of 1-arylaminopentenes proceeds with high efficiency and high irans-diastereoselectivity, whereas the resolution process of 1-alkylaminopentenes suffers from decreasing resolution efficiency with increasing steric demand of the aliphatic substituent. Kinetic studies of the matching and mismatching substrate-catalyst pair by using enantiopure substrates and either the (R)- or (S)-binaphtholate catalysts revealed that the difference in resolution efficiency stems from a shift of the Curtin-Hammett pre-equilibrium. Al-though 1-arylaminopentenes favor the matching substrate-catalyst complex, preference for the mismatching substrate-catalyst complex for 1-alkylaminopentenes diminishes resolution efficiency. Nevertheless, the relative cyclization rate for the two diastereomeric substrate-catalyst complexes remains in a typical range of 7-10:1. Plausible attractive π interactions between the aryl substituent and either the metal center or the aromatic system of the bis(triarylsilyl)-substituted binaphtholate ligand may explain increased sta-bility of the matching substrate-catalyst complex. Incidentally, the methoxymethyl (MOM)-substituted aminopentene 3g also exhibited a strong preference for the matching substrate-catalyst complex, possibly due to the chelating nature of the MOM substituent. The proximity of the stereocenter to the amino group in the aminoalkene substrate was crucial to achieve good kinetic resolution efficiency. The more remote β-phenyl substituent in 2-phenylpent-4-en-l-amine (5) resulted in diminished discrimination of the substrate enantiomers with respect to the relative rate of cyclization of the two substrate-catalyst complexes and a Curtin-Hammett preequilibrium close to unity.
