- Synthesis and Reactivity of NNNNN-Pincer Multidentate Pyrrolyl Rare-Earth-Metal Amido-Chloride or Dialkyl Complexes
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The NNNNN-pincer multidentate pyrrolyl rare-earth-metal amido-chloride complexes {η1:κ3-2,5-[CH3N(CH2CH2)2NCH2]2C4H2N}RECl[N(SiMe3)2] (RE = Y (2a), Sm (2b), Dy (2c), Er (2d), Yb (2e)) were synthesized by one step from reactions of [(Me3Si)2N]3RE(μ-Cl)Li(T
- Cui, Peng,Du, Jun,Huang, Zeming,Sheng, Weiming,Wang, Shaowu,Wei, Yun,Xu, Xiaolong,Zhang, Lijun,Zhang, Xiuli,Zhou, Shuangliu,Zhu, Xiancui
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supporting information
p. 4525 - 4534
(2020/12/22)
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- Synthesis of substituted guanidines using Zn-Al hydrotalcite catalyst
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Substituted guanidines were synthesized by the guanylation of amines with carbodiimides using Zn-Al hydrotalcite (Zn-Al HT) catalyst. Zn-Al HT was prepared by co-precipitation method and characterized by X-ray powder diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman and Thermogravimetric-Differential Thermal Analysis (TG-DTA). The heterogeneous catalyst afforded moderate to good yields (~50-60 %) of substituted guanidines in toluene at 110?C in 12 h. The catalyst was recovered quantitatively by simple filtration and reused for three cycles with consistent activity. The XRD and FTIR studies of the used catalyst shows no variation in the structure of the catalyst even after three recycles. Indian Academy of Sciences.
- Mannepalli, Lakshmi Kantam,Dupati, Venkanna,Vallabha, Swarna Jaya,Sunkara, V Manorama
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p. 1339 - 1345
(2014/04/03)
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- Catalytic guanylation of aliphatic, aromatic, heterocyclic primary and secondary amines using nanocrystalline zinc(II) oxide
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Nanocrystalline ZnO was found to be a highly efficient heterogeneous catalyst for the guanylation of amines with various carbodiimides to afford N,N′,N″-trisubstituted guanidines in excellent yields. Structurally divergent aliphatic, aromatic, heterocyclic primary and secondary amines were converted to the corresponding N,N′,N″-trisubstituted guanidines using optimal conditions. The catalyst was easy to handle even under atmospheric conditions and can be easily recovered by centrifugation and reused for five cycles with consistent activity.
- Kantam, M. Lakshmi,Priyadarshini,Amal Joseph,Srinivas,Vinu,Klabunde,Nishina, Yuta
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experimental part
p. 5730 - 5737
(2012/09/08)
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- Synthesis, reactivity, and computational analysis of halophosphines supported by dianionic guanidinate ligands
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The reported chemistry and reactivity of guanidinate supported group 15 elements in the +3 oxidation state, particularly phosphorus, is limited when compared to their ubiquity in supporting metallic elements across the periodic table. We have synthesized a series of chlorophosphines utilizing homo- and heteroleptic (dianionic)guanidinates and have completed a comprehensive study of their reactivity. Most notable is the reluctancy of these four-membered rings to form the corresponding N-heterocyclic phosphenium cations, the tendency to chemically and thermally eliminate carbodiimide, and the scarcely observed ring expansion by insertion of a chloro(imino)phosphine into a P-N bond of the P-N-C-N framework. Computational analysis has provided corroborating evidence for the unwillingness of the halide abstraction reaction by demonstrating the exceptional electron acceptor properties of the target phosphenium cations and the underscoring strength of the P-X bond.
- Brazeau, Allison L.,Haenninen, Mikko M.,Tuononen, Heikki M.,Jones, Nathan D.,Ragogna, Paul J.
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body text
p. 5398 - 5414
(2012/05/20)
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- An efficient one-pot synthesis of 3-aryl-1,2,4-oxadiazol-5-amines under solvent-free conditions
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The in situ prepared amidoximes from the reaction between nitriles and hydroxylamine are condensed with carbodiimides in the presence of molecular sieves under solvent-free conditions to produce the title compounds in excellent yields.
- Adib, Mehdi,Bagherzadeh, Sharareh,Mahdavi, Mohammad,Bijanzadeh, Hamid R.
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body text
p. 50 - 51
(2010/04/25)
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- Syntheses and15N NMR Spectra of Iminodiaziridines - Ring-Expansions of 1-Aryl-3-iminodiaziridines to 1H- and 3aH-Benzimidazoles, 2H-Indazoles, and 5H-Dibenzo[d,f] [1,3]diazepines
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Iminodiaziridines are synthesized, by (i) 1,3-dehydrochlorination with potassium, teri-butoxide of N-chloroguanidines, generated in situ from. N,N′,N″-substituted guanidines with tert-butyl hypochlorite, and (ii) base-mediated 1,3-elimination of sulfuric acid from N,N',N″- substituted hydroxyguanidine O-sulfonic acids. At elevated temperatures, (alkylimino)diaziridines undergo valence isomerization by 1,3shift, [2+1] cycloelimination to afford isocyanides and diazenes, and ring-opening elimination to yield alkylideneguanidines. N′-Aryl-N-hydroxyguanidine O-sulfonic acids furnish (N-arylimino)diaziridines, but no 1-aryl-3- iminodiaziridines, instead giving rearranged isomere. Precursors containing perdeuterated feri-butyl groups give rearranged products that show complete scrambling. This indicates that l-aryl-3iminodiaziridines are intermediates that undergo very rapid I degenerate valence isomerization. Provided that the ortho aryl positions are substituted, high yields of (arylimino)diaziridines are obtained, along with 2-imino-2,3-dihydro-3aHbenzimidazoles, Otherwise, 2-amino-lH-benzimidazoles and strongly fluorescent 3-amino-2H-indazoles, originating from rearrangements of the elusive l-aryl-3-iminodiaziridines, predominate. N',N″-Diaryl-N-hydroxyguanidine O-sulfonic acids give only rearranged products: a 2-amino-1H-benzimidazole and a 6-amino-5H-dibenzo[d,f][1. 3]diazepine if aryl = phenyl, or a 2-imino-2,3-dihydro-3aH-benzimidazole if aryl = mesityl. 3aH-Benzimidazoles slowly dimerize through Diels-Alder reactions. 15N NMR signals were assigned, to the syn and anti ring nitrogen atoms of iminodiaziridines with the help of a combination of homonuclear NOE and HNHMBC or HN-gHMBC experiments.
- Quast, Helmut,Ross, Karl-Heinz,Philipp, Gottfried,Hagedorn, Manfred,Hahn, Harald,Banert, Klaus
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experimental part
p. 3940 - 3952
(2010/03/01)
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- Titanacarborane mediated C-N bond forming/breaking reactions
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Constrained-geometry titanacarboranes [σ:η1:η5-(OCH2)(R2NCH2)C2B9H9]Ti(NR2) (R = Me, Et) are synthesized via an unexpected reaction of [Me3NH][μ-7,8-CH2OCH2-7,8-C2B9H10] with Ti(NR2)4 (R = Me, Et), involving a C-O bond cleavage and C-N bond formation. These complexes can be readily converted to new amide species or alkoxide by reacting with amines or esters, respectively. Insertion of a series of unsaturated molecules into the Ti-N bond of the aforementioned complexes results in the formation of various half-sandwich titanacarboranes. [σ:η1:η5-(OCH2)(Me2NCH2)C2B9H9]Ti(NMe2) is also able to efficiently catalyze the hydroamination of carbodiimides and the transamination of guanidines. These results are summarized in this brief account.
- Shen, Hao,Xie, Zuowei
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scheme or table
p. 1652 - 1657
(2009/10/11)
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- Superbase catalysis of oxazolidin-2-one ring formation from carbon dioxide and prop-2-yn-1-amines under homogeneous or heterogenous conditions
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N-alkyl-substituted prop-2-yn-1-amines and N-tri-, tetra- and penta-alkyl-substituted guanidines or other strong organic bases assemble under the action of carbon dioxide to afford carbamates, from which methyleneoxazolidinones 2 are formed by ring closure. If alkyl or cycloalkyl chains of appropriate length are present in the guanidines the reaction readily occurs under heterogenous conditions without solvent.
- Costa, Mirco,Chiusoli, Gian Paolo,Taffurelli, Davide,Dalmonego, Giulio
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p. 1541 - 1546
(2007/10/03)
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- Katalytische C-C- und C-N-Kupplungsreaktionen von Carbodiimiden durch Uebergangsmetallcluster
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N,N'-Dialkyl carbodiimides react with hydrogen in the presence of ruthenium clusters to give new N,N',N''-trialkyl guanidines.The reaction with terminal acetylenes, catalyzed by a bimetallic cluster system, leads to new N,N'-dialkyl propiolamidines.
- Schmidt, Gerhard F.,Suess-Fink, Georg
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p. 207 - 212
(2007/10/02)
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- The Dehydration of Ureas by Two-Phase Dichlorocarbene Reaction, a Synthetic Access to Substituted Cyanamides
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A wide variety of N,N-disubstituted ureas are dehydrated in the CHCl3/NaOH catalytic two-phase system under mild conditions.The sequence of urea-transamidation and dehydration thus offers a profitable approach to aprotic cyanamides.Among various tested PT-catalysts tertiary amines prove to be the most efficient and favourable ones.Tertiary amines may also be used advantageously in the transformation of carboxylic amides and thioamides to the corresponding nitriles.The application of the same technique is less suitable in the case of N-mono-substituted ureas, N,N'-disubstituted ureas as well as N(dialkylaminomethylidene)ureas, because consequent reactions of the primarily formed cyanamides predominate.Problems concerning the dehydration mechanism are elucidated in terms of HMO-perturbation theory.
- Schroth, W.,Kluge, H.,Frach, R.,Hodek, W.,Schaedler, H. D.
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p. 787 - 802
(2007/10/02)
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