- The catalytic effects of in situ prepared N-heterocyclic carbenes from benzimidazole salts in Suzuki–Miyaura cross-coupling reaction and uses in catalytic preparation of 1,3,5-triphenyl-1,3,5-triazinane-2,4,6-trione from phenyl isocyanate
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Many benzimidazole salts bearing a 3-phenylpropyl substituent (1a–1h) were synthesized and their structures were identified by1 H NMR,13 C NMR, and IR spectroscopic methods and elemental analysis. These N-heterocyclic carbene (NHC) precursors were used as a part of a catalytic system including Pd(OAc) 2 and the base in the Suzuki–Miyaura cross-coupling reaction under microwave irradiation. They were also used as catalysts in the cyclotrimerization of phenyl isocyanate to yield 1,3,5-triphenyl-1,3,5-triazinane-2,4,6-trione. It has been observed that benzimidazole salts made a positive contribution to both catalytic reactions as a NHC precursor.
- Yilmaz, ülkü,Kü?ükbay, Hasan
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Read Online
- Phosphorylation of isocyanates and aldehydes mediated by multifunctional n-phosphine oxide-substituted imidazolylidenes
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The direct syntheses of imidic-phosphinic mixed anhydrides and phosphinates were accomplished via phosphorylation of isocyanates or aldehydes with N-phosphine oxide-substituted imidazolylidenes (PoxIms) that are equipped with both nucle-ophilic carbene an
- Hoshimoto, Yoichi,Asada, Takahiro,Hazra, Sunit,Ohashi, Masato,Ogoshi, Sensuke
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Read Online
- Guanidinate stabilized germanium(II) and tin(II) amide complexes and their catalytic activity for aryl isocyanate cyclization
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Two different synthetic routes for the preparation of guanidinate stabilized germanium(II) and tin(II) amide complexes have been established. First, the reaction of one equiv of bulky guanidine ligand either L1H or L2H [L1
- Barman, Milan Kr,Baishya, Ashim,Peddarao, Thota,Nembenna, Sharanappa
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Read Online
- Development of high-performance networked polymers consisting of isocyanurate structures based on selective cyclotrimerization of isocyanates
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Selective and quantitative cyclotrimerization of p-tolylisocyanate proceeded by using sodium p-toluenesulfinate as a catalyst and 1,3-dimethylimidazolidinone as a solvent. Exploitation of this system to the cyclotrimerization of methylene diphenyl 4,4′-di
- Moritsugu, Masaki,Sudo, Atsushi,Endo, Takeshi
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- Orthorhombic and monoclinic polymorphs of 1,3,5-triphenylperhydro-1,3,5-triazine-2,4,6-trione at 120 K: Chains and sheets formed by c - h...π(arene) hydrogen bonds
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The orthorhombic and monoclinic polymorphs of 1,3,5-triphenylperhydro-1,3,5-triazine-2,4,6-trione, were analyzed at 120 K with chains and sheets formed by C-H...π(arene) hydrogen bonds. The orthorhombic polymorph crystallized in space group Fdd2, molecule
- Mariyatra, M. Baby,Panchanatheswaran, Krishnaswamy,Low, John N.,Glidewell, Christopher
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- New Insights in Frustrated Lewis Pair Chemistry with Azides
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The geminal frustrated Lewis pair (FLP) tBu2PCH2BPh2 (1) reacts with phenyl-, mesityl-, and tert-butyl azide affording, respectively, six, five, and four-membered rings as isolable products. DFT calculations revealed that
- Boom, Devin H. A.,Jupp, Andrew R.,Nieger, Martin,Ehlers, Andreas W.,Slootweg, J. Chris
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Read Online
- Transition-metal-mediated activation of arylisocyanates in supercritical carbon dioxide
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The reactivity of arylisocyanates in supercritical carbon dioxide (scCO2) was studied using the easily available complexes CpCo(CO)2, CpCoPPh3Me2 and Ni(cod)2 as catalysts. A study of the solubility o
- Montilla, Francisco,Clara, Elisabete,Avilés, Teresa,Casimiro, Teresa,Aguiar Ricardo, Ana,Nunes Da Ponte, Manuel
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Read Online
- 'Push-Pull' and spirobicyclic structures by reacting N-methyl cyclic ketene-N,X (X=S, O)-acetals with isocyanates and isothiocyanates
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Nucleophilic N-methyl cyclic ketene-N,X (X=S, O)-acetals can react with electrophilic aryl isocyanates and aryl isothiocyanates to form 'push-pull' mono-adducts, di-adducts and spirobicyclic 6/5 ring compounds.
- Zhou, Aihua,Cao, Liwei,Li, Haiqing,Liu, Zhuqing,Cho, Hosouk,Henry, William P.,Pittman, Jr., Charles U.
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Read Online
- Preparation, Characterization, and X-Ray Structure Studies of Tertiary Phosphine Coordinated Molybdenocene
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Cp2MoH(OTs) (Cp = η-C5H5, Ts = p-CH3C6H4SO2), which was prepared from Cp2MoH2 by its treatment with TsOH in EtOH, reacted with tertiary phosphines and phosphite to give cationic +TsOH- where R = Ph, Et, OEt, Cy, and Bus
- Ito, Takashi,Tokunaga, Tadayuki,Minato, Makoto,Nakamura, Takashi
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- Generation of low-valent alkoxy niobium from Nb(OEt)5 and Grignard reagents and their use as catalysts in the cyclotrimerization of isocyanates
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A new highly active low-valent alkoxyniobium species has been developed following the reaction of Nb(OEt)5 with Grignard reagent such as i-PrMgCl or EtMgCl, with the material behaving as an efficient catalyst for cyclotrimerization reaction of isocyanates. In this reagent system, the existence of a lowvalent niobium species was confirmed by the formation of the niobiumealkyne complex prepared from the Nb(OEt)5/Grignard reagent system and an alkyne. Furthermore, the hydrolysis and diallylation reactions of the niobiumealkyne complex provided further confirmation of its existence, with corresponding (Z)-alkene and diallylated products being isolated in good yields.
- Ozaki, Makoto,Obora, Yasushi,Tada, Yusuke,Ishii, Yasutaka
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Read Online
- Synergistic Catalysis by Br?nsted Acid/Carbodicarbene Mimicking Frustrated Lewis Pair-Like Reactivity
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Carbodicarbene (CDC), unique carbenic entities bearing two lone pairs of electrons are well-known for their strong Lewis basicity. We demonstrate herein, upon introducing a weak Br?nsted acid benzyl alcohol (BnOH) as a co-modulator, CDC is remolded into a Frustrated Lewis Pair (FLP)-like reactivity. DFT calculation and experimental evidence show BnOH loosely interacting with the binding pocket of CDC via H-bonding and π-π stacking. Four distinct reactions in nature were deployed to demonstrate the viability of proof-of-concept as synergistic FLP/Modulator (CDC/BnOH), demonstrating enhanced catalytic reactivity in cyclotrimerization of isocyanate, polymerization process for L-lactide (LA), methyl methacrylate (MMA) and dehydrosilylation of alcohols. Importantly, the catalytic reactivity of carbodicarbene is uniquely distinct from conventional NHC which relies on only single chemical feature of nucleophilicity. This finding also provides a new spin in diversifying FLP reactivity with co-modulator or co-catalyst.
- Bai, Yuna,Chan, Yi-Chen,Chen, Hsing-Yin,Chen, Hsuan-Ying,Chen, Wen-Ching,Li, Chen-Yu,Ong, Tiow-Gan,Tseng, Mei-Chun,Wu, Ying-Yann,Yap, Glenn P. A.,Zhao, Lili
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supporting information
p. 19949 - 19956
(2021/08/03)
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- Method for preparing aromatic isocyanate terpolymer
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The invention discloses a method for preparing an aromatic isocyanate terpolymer in the field of high polymer material synthesis, which comprises the following steps of S1, respectively taking dimethylacetamide, ethanol and sodium hydride, taking dimethylacetamide as a solvent, taking ethanol and sodium hydride as catalysts, adding into a flask, and reacting at room temperature, S2, dropwise adding aromatic isocyanate as a reaction substrate, and carrying out a heating reaction under magnetic stirring, S3, after the mixture is cooled to the room temperature, pouring the mixture into ultrapure water to separate out a product, filtering the product, washing the precipitate with water and ethanol in sequence, and drying the precipitate in a drying oven to obtain a crude product. According to the method, dimethylacetamide is used as a solvent, under the condition that ethanol is not changed, a small amount of sodium hydride is used for base catalysis of polymerization of aromatic isocyanate such as 3, 5-dimethyl phenyl isocyanate to synthesize the compound aromatic isocyanate tripolymer, the yield of the aromatic isocyanate tripolymer can be increased, the cost can be reduced, and use by people is facilitated.
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Paragraph 0020; 0022; 0030-0031; 0033-0039
(2021/06/22)
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- Aluminium-catalysed isocyanate trimerization, enhanced by exploiting a dynamic coordination sphere
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Main-group metals are inherently labile, hindering their use in catalysis. We exploit this lability in the synthesis of isocyanurates. For the first time we report a highly active catalyst that trimerizes alkyl, allyl and aryl isocyanates, and di-isocyanates, with low catalyst loadings under mild conditions, using a hemi-labile aluminium-pyridyl-bis(iminophenolate) complex.
- Bahili, Mohammed A.,Stokes, Emily C.,Amesbury, Robert C.,Ould, Darren M. C.,Christo, Bashar,Horne, Rhian J.,Kariuki, Benson M.,Stewart, Jack A.,Taylor, Rebekah L.,Williams, P. Andrew,Jones, Matthew D.,Harris, Kenneth D. M.,Ward, Benjamin D.
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supporting information
p. 7679 - 7682
(2019/07/08)
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- Potassium complexes containing bidentate pyrrole ligands: Synthesis, structures, and catalytic activity for the cyclotrimerization of isocyanates
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Bidentate pyrrolyl ligands, 2-(t-butyliminomethyl)pyrrole and 2-(t-butylaminomethyl)pyrrole, reacted with KH to give complexes [C4H3N(2-CHNtBu)K(THF)]n (1) and [C4H3N(2-CH2NHsup
- Guo, Zhiqiang,Xu, Yuan,Wu, Xiaoqin,Wei, Xuehong,Xi, Chanjuan
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supporting information
p. 8116 - 8121
(2019/06/19)
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- Highly efficient cyclotrimerization of isocyanates using N-heterocyclic olefins under bulk conditions
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With a catalyst loading as low as 0.005%, high to excellent yields of isocyanurates could be achieved from N-heterocyclic olefin mediated organocatalytic cyclotrimerization of a wide range of isocyanates under bulk conditions. Experimental details coupled with structural characterization of the key intermediates led to comprehensive mechanistic studies of cyclotrimerization.
- Li, Chengkai,Zhao, Wuchao,He, Jianghua,Zhang, Yuetao
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supporting information
p. 12563 - 12566
(2019/10/28)
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- Reactivities of zero-valent group 10 complexes toward organic isocyanates: Synthesis of metallacycles containing dimeric isocyanate units, isocyanate cyclotrimerization, and computational chemistry
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The reactions of [Pd(olefin)(PR3)2] (PR3 = PMe3, PMe2Ph) with two equivalents of an aryl or alkyl isocyanate afford cis-[Pd{-N(R)C(O)N(R)C(O)-}(PR3)2] (R = 1-naphthyl, 4-phenoxyphenyl), which are five-membered palladacycles bearing dimeric isocyanate units, or cyclic tetramers as assemblies of four five-membered palladacycles, [Pd{C(O)N(R′)C(O)N(R′)}(PMe3)]4, (R′ = 3-methylbenzyl, 4-methylbenzyl or 4-methoxybenzyl), depending on the alkyl substituent on R-NCO. Interestingly, these reactions afford cyclic trimers as catalytic products when two equivalents or excess amounts of benzyl isocyanate are used. In contrast, reactions of [Pt(olefin)(PR3)2] with two equivalents of an alkyl or aryl isocyanate afford only the five-membered platinacycle, namely cis-[Pt{-N(R)C(O)N(R)C(O)-}(PMe3)2] (R = 3-methylbenzyl, 4-methylbenzyl, 4-fluorobenzyl, 4-methoxybenzyl, (S)-(+)-(1-naphthyl)ethyl, (R)-(-)-(1-naphthyl)ethyl, 4-phenoxyphenyl and 2,6-difluorophenyl). Aided by theoretical calculations, we propose mechanisms for the formation of the five-membered palladacycle or platinacycle, the cyclic tetramer, and the cyclotrimerization of the organic isocyanate. In addition, the ligand-exchange reactions between a five-membered platinacycle bearing a chiral substituent such as (S)-(+)-(1-naphthyl)ethyl or (R)-(-)-(1-naphthyl)ethyl) moieties and 1,2-bis(diethylphosphino)ethane (DEPE), a chelating phosphine, clearly afford the corresponding platinacycle bearing a DEPE ligand with retention of chirality. On the other hand, reactions of [Ni(COD)2] with various organic isocyanates in the presence of tertiary phosphines only afford the corresponding cyclic trimers. In contrast, similar reactions in the presence of N-heterocyclic carbenes (NHC) such as 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) or 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidine (SIPr) afford unexpected adducts between R-NCO and the NHC ligand.
- Han, Young-Sung,Jung, Kang-Yeoun,Kim, Yong-Joo,Baeck, Kyoung Koo,Lee, Gang Min,Lee, Soon W.
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p. 15614 - 15625
(2019/10/19)
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- Lithium complex of 2-amino-functionalized benzoylpyrrole: Synthesis, structure, and catalytic activity for the cyclotrimerization of isocyanates
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Lithium complex stabilised by 2-amino-functionalized benzoylpyrrole was synthesized, and its structural features were provided. The molecular structure shows a novel tetrameric cage structure, which includes a eight-membered (LiN)4 ring and a e
- Guo, Zhiqiang,Wang, Yakong,Yang, Jihong,Wei, Xuehong
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- Imidazolin-2-iminato Ligand-Supported Titanium Complexes as Catalysts for the Synthesis of Urea Derivatives
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The reactions of tetrakis(dimethylamido)titanium(IV) [Ti(NMe2)4] with three different imidazolin-2-imines (ImRNH; R = tert-butyl (tBu), mesityl (Mes), and 2,6-diisopropylphenyl (Dipp)) afforded the corresponding titanium i
- Naktode, Kishor,Das, Suman,Bhattacharjee, Jayeeta,Nayek, Hari Pada,Panda, Tarun K.
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p. 1142 - 1153
(2016/02/09)
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- Lithium, magnesium, zinc complexes supported by tridentate pincer type pyrrolyl ligands: Synthesis, crystal structures and catalytic activities for the cyclotrimerization of isocyanates
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Lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands were synthesized conveniently and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated. The reac
- Liu, Qiao,Guo, Zhiqiang,Han, Hongfei,Tong, Hongbo,Wei, Xuehong
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- Lithium, magnesium, zinc complexes supported by tridentate pincer type pyrrolyl ligands: Synthesis, crystal structures and catalytic activities for the cyclotrimerization of isocyanates
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Lithium, magnesium, zinc complexes incorporating substituted symmetrical tridentate pyrrolyl ligands were synthesized conveniently and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated. The reac
- Liu, Qiao,Guo, Zhiqiang,Han, Hongfei,Tong, Hongbo,Wei, Xuehong
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supporting information
p. 15 - 19
(2015/03/05)
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- Synthesis and characterization of chiral poly(alkyl isocyanates) by coordination polymerization using a chiral half-titanocene complex
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A new chiral half-titanocene complex, [CpTiCl2(O-(S)-2-Bu)], is synthesized and characterized by 1H and 13C NMR spectroscopy. This complex is employed for the coordination polymerization of n-butyl and n-hexyl- isocyanate
- Choinopoulos, Ioannis,Koinis, Spyros,Pitsikalis, Marinos
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p. 2141 - 2151
(2015/08/11)
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- Tridentate pyrrolylzinc compounds: Synthesis, structures, reactivities and catalytic cyclotrimerization reaction of isocyanate
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The reactions of ZnEt2 with NNN-tridentate pincer type pyrrolyl ligands, 2,5-bis((dimethylamino)methylene)-1H-pyrrole (HL1), 2,5-bis((pyrrolidin-1-yl)methylene)-1H-pyrrole (HL2) and 2,5-bis((piperidino)methylene)-1H-pyrrol
- Guo, Zhiqiang,Wei, Xuehong,Tong, Hongbo,Liu, Diansheng
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p. 136 - 142
(2015/01/08)
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- Cyclo-oligomerization of isocyanates with Na(PH2) or Na(OCP) as "p-" anion sources
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We show that the 2-phosphaethynolate anion, OCP-, is a simple and efficient catalyst for the cyclotrimerization of isocyanates. This process proceeds step-wise and involves five-membered heterocycles, namely 1,4,2-diazaphospholidine-3,5-dionide anions and spiro-phosphoranides as detectable intermediates, both of which were also found to be involved in the catalytic conversion. These species can be considered as adducts of a phosphide anion with two and four isocyanate molecules, respectively, demonstrating that the OCP- anion acts as a formal "P-" source. The interconversion between these anionic species was found to be reversible, allowing them to serve as reservoirs for unique phosphorus-based living-catalysts for isocyanate trimerization.
- Heift, Dominikus,Benko, Zoltán,Grützmacher, Hansj?rg,Jupp, Andrew R.,Goicoechea, Jose M.
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p. 4017 - 4024
(2015/06/25)
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- An expeditious method for the selective cyclotrimerization of isocyanates initiated by TDAE
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We developed a rapid and green synthesis of various isocyanurates by cyclotrimerization of isocyanates using TDAE (tetrakis(dimethylamino)ethylene). TDAE displays excellent performance in catalytic quantities, affording the corresponding trimer of isocyanates very rapidly, under air and at room temperature in good to excellent yields.
- Giuglio-Tonolo, Alain G.,Spitz, Cédric,Terme, Thierry,Vanelle, Patrice
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p. 2700 - 2702
(2014/05/06)
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- Bidentate pyrrolyl lithium complexes: Synthesis, crystal structure and catalytic activity for the cyclotrimerization of isocyanates
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Three bidentate pyrrolyl lithium complexes were synthesized and their application for the cyclotrimerization of isocyanate to corresponding isocyanurate has been investigated and show high catalytic activities. All lithium complexes were characterized by
- Guo, Zhiqiang,Wang, Song,Tong, Hongbo,Chao, Jianbin,Wei, Xuehong
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- Phenyl isocyanate anion radicals and their cyclotrimerization to triphenyl isocyanurate anion radicals
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Room-temperature sodium metal reduction of phenyl isocyanate (PhNCO) in hexamethylphosphoramide yields the anion radical (PhNCO?-) where the unpaired electron exhibits coupling to one nitrogen and five unique protons. The extent of coupling to
- Servos, Mark A.,Smart, Nathaniel C.,Kassabaum, Mark E.,Scholtens, Cody A.,Peters, Steven J.
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p. 3908 - 3917
(2013/06/05)
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- Reactive N-protonated isocyanate species stabilized by bis(μ-hydroxo) divanadium(IV)-substituted polyoxometalate
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O- or N-protonated? The bis(μ-hydroxo)divanadium(IV)-substituted γ-Keggin-type polyoxometalate (see picture, left) (TBA) 4[γ-SiVIV2W10O 36(μ-OH)4] (TBA=tetra(n-butyl)ammonium) was synthesiz
- Uehara, Kazuhiro,Fukaya, Keisuke,Mizuno, Noritaka
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p. 7715 - 7718
(2012/09/05)
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- Orthoamides and iminium salts LXXIV [1]. Reactions of N,N,N',N'- Tetramethyl-chloroformamidiniumChloride with metals
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N,N,N',N'-Tetramethyl-formamidinium chloride (2a) reacts with elemental sodium in various solvents to give N,N,N',N',N'',N''-hexamethyl-guanidinium chloride (4a). The reaction of 2a with potassium affords N,N,N',N',N'',N'',N''', N'''-octamethyl-oxamidinium dichloride (3a). From the reaction of 2a with magnesium in different solvents in general result mixtures of the salts 4a, 3a and N,N,N',N'-tetramethyl-formamidinium chloride (10a). The composition of these mixtures depends on the solvent and the reaction temperature. Similar results are obtained, when a zinc'copper couple is used instead of magnesium. Very likely from 2a and magnesium or zinc, respectively, organometallic intermediates 11, 12 are formed which could be trapped by aromatic aldehydes and phenylisocyanate. The salt 2a can be reductively coupled by a low-valent titanium reagent to give the oxamidinium salt 3a.
- Kantlehner, Willi,Aichholz, Reiner,Karl, Martin
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experimental part
p. 305 - 319
(2012/07/13)
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- Lanthanide(III) 4,6-dimethylpyrimidine-2-thionate complexes as efficient catalysts for isocyanate cyclodimerization
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Protonolysis reactions of [(Me3Si)2N] 3Ln(μ-Cl)Li(THF)3 (Ln = Pr, Nd, Sm, Eu) with 3 equiv of 4,6-dimethylpyrimidine-2-thiol (dmpymtH) gave rise to the four Ln(III) pyrimidine-2-thionate complexes Li[Ln(dmpymt)4] (Ln = Pr (1), Nd (2), Sm (3), Eu (4)). Compounds 1-4 were characterized by elemental analysis, IR and 1H NMR spectroscopy, and single-crystal X-ray diffraction. X-ray diffraction analysis shows that the structures of 1-4 are similar and each eight-coordinate Ln(III) ion is chelated by four dmpymt ligands. Complexes 1-4 display excellent catalytic performance in the cyclodimerization of isocyanates to produce substituted ureas via elimination of CO, which represents the first example of lanthanide thiolates exhibiting a high catalytic activity and a high selectivity in the cyclodimerization of isocyanates. The effects of the solvents, temperatures, catalyst loadings, and rare-earth metals on the catalytic activities of the complexes were examined.
- Li, Hong-Xi,Cheng, Mei-Ling,Wang, He-Ming,Yang, Xiao-Juan,Ren, Zhi-Gang,Lang, Jian-Ping
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experimental part
p. 208 - 214
(2011/03/17)
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- Lithium dibenzylamide, a simple, selective and highly efficient catalyst for isocyanate cyclotrimerization to isocyanurate
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Lithium dibenzylamide catalyzed the rapid and essentially quantitative cyclotrimerization of a variety of isocyanates under mild conditions and could be recycled for six times in high yield. Georg Thieme Verlag Stuttgart New York.
- Shi, Jingchao,Guo, Zhiqiang,Wei, Xuehong,Liu, Diansheng,Lappert, Michael F.
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supporting information; scheme or table
p. 1937 - 1939
(2011/10/01)
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- Cyclodimerization and cyclotrimerization of isocyanates promoted by one praseodymium benzenethiolate complex [Pr(SPh)3(THF)3]
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The cyclotrimerization of aryl isocyanates and the cyclodimerization of alkyl isocyanates initiated by one praseodymium benzenethiolate complex [Pr(SPh)3(THF)3] were investigated. Comparative runs with [Pr(SPh)3(THF)3] and its precursor Pr[(Me 3Si)2N]3 showed that the former has the advantages of a higher selectivity toward isocyanates, easy preparation, low catalyst loading, high conversion as well as mild reaction conditions.
- Wang, He-Ming,Li, Hong-Xi,Yu, Xiang-Yang,Ren, Zhi-Gang,Lang, Jian-Ping
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experimental part
p. 1530 - 1535
(2011/04/15)
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- Insertion of isocyanate and isothiocyanate into the ln-p σ-bond of organolanthanide phosphides
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The synthesis, structure, and reactivity of organoyttrium phosphides toward phenyl isocyanate (PhNCO) and phenyl isothiocyanate (PhNCS) are described. Reaction of (TpMe2)CpYCH2Ph(THF) (TpMe2 = tris(3,5-dimethylpyrazolyl) b
- Yi, Weiyin,Zhang, Jie,Hong, Longcheng,Chen, Zhenxia,Zhou, Xigeng
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experimental part
p. 5809 - 5814
(2012/01/04)
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- Kinetic and thermodynamic evaluation of the reversible N-heterocyclic carbene-isothiocyanate coupling reaction: Applications in latent catalysis
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Using stopped flow and other spectroscopic techniques, the thermodynamic parameters of the coupling reaction between 1,3-dimesitylimidazolylidene and phenyl isothiocyanate were determined (Ho = -96.1 kJ mol-1 and ΔSo = -39.6 J mol-1 K-1). On the basis of these data which indicated that the reaction was reversible (K eq = 5.94 × 1014 M-1 at 25 °C; k f = 252 M-1 s-1; kr = 4.24 × 10-13 s-1), the adduct formed from the two aforementioned coupling partners was used as a latent catalyst to facilitate the [2 + 2 + 2] cyclotrimerization of phenyl isocyanate and the polymerization of dl-lactide.
- Norris, Brent C.,Sheppard, Daniel G.,Henkelman, Graeme,Bielawski, Christopher W.
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scheme or table
p. 301 - 304
(2011/03/19)
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- Amine-linked N-heterocyclic carbenes: The importance of an pendant free-amine auxiliary in assisting the catalytic reaction
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We have successfully expanded the library of amino-NHCs with varying substituents on the amine group, leading to insight about the instability of NHCs arising from the intermolecular interaction of the dangling amine side-arm. However, the pendant amine plays an important role with respect to the catalytic process, resuscitating the catalytic activity of unsaturated NHC's through a synergistic effect invoked by the secondary amine. This proof of concept allows us to expand the spectrum of catalysis to C-C, as well as C-B bond formation. Copyright
- Li, Chia-Yi,Kuo, Yi-Yin,Tsai, Jie-Hong,Yap, Glenn P. A.,Ong, Tiow-Gan
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supporting information
p. 1520 - 1524
(2013/01/11)
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- Reaction of 3-hydroxyquinoline-2,4-diones with isocyanates and thermally induced transformation of the reaction products
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3-Hydroxyquinoline-2,4-diones 1 react with isocyanates to give novel 1,2,3,4-tetrahydro-2,4-dioxoquinolin-3-yl (alkyl/aryl)carbamates 2 and/or 1,9b-dihydro-9b-hydroxyoxazolo[5,4-c]quinoline-2,4(3aH,5H)-diones 3. Both of these compounds are converted, by boiling in cyclohexylbenzene solution in the presence of Ph3P or 4-(dimethylamino)pyridine, to give 3-(acyloxy)-1,3-dihydro-2H-indol-2-ones 8. All compounds were characterized by IR, and 1H- and 13C-NMR spectroscopy, as well as by EI mass spectrometry. Copyright
- Mrkvicka, Vladimir,Lycka, Antonin,Vicha, Robert,Klasek, Antonin
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experimental part
p. 78 - 91
(2011/03/16)
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- An electron-rich proazaphosphatrane for isocyanate trimerization to isocyanurates
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(Figure presented) A facile synthesis of the new electron-rich, sterically hindered proazaphosphatrane shown above is described herein. This proazaphosphatrane catalyzes the cyclotrimerization of a wide variety of isocyanates to isocyanurates under mild c
- Raders, Steven M.,Verkade, John G.
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experimental part
p. 5308 - 5311
(2010/10/19)
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- Organocatalytic, rapid and facile cyclotrimerization of isocyanates using tetrabutylammonium phthalimide-N-oxyl and tetraethylammonium 2-(carbamoyl)benzoate under solvent-free conditions
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Tetrabutylammonium phthalimide-N-oxyl and tetraethylammonium 2-(carbamoyl)benzoate were found to be effective and easily accessible organocatalysts for selective cylotrimerization of aryl and alkyl isocyanates under mild reaction conditions. The reaction proceeds smoothly using very low catalyst loadings of these metal-free organocatalysts (0.025 and 0.25 mol%, respectively) under solvent-free conditions at room temperature within a very short reaction time.
- Dekamin, Mohammad G.,Varmira, Kambiz,Farahmand, Mehdi,Sagheb-Asl, Solmaz,Karimi, Zahra
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experimental part
p. 226 - 230
(2011/09/14)
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- Polymer-supported, carbon dioxide-protected n-heterocyclic carbenes: Synthesis and application in organo- and organometallic catalysis
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The synthesis of a resin-supported, carbon dioxide-protected N-heterocyclic carbene (NHC) and its use in organocatalysis and organometallic catalysis are described. The resin-bound carbon dioxide-protected NHC-based catalyst was prepared via ring-opening
- Pawar, Gajanan Manohar,Buchmeiser, Michael R.
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scheme or table
p. 917 - 928
(2010/06/15)
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- CO2 and SnII adducts of N-heterocyclic carbenes as delayed-action catalysts for polyurethane synthesis
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A series of CO2-protected pyrimidin-2-ylidenes as well as 1,3-dimesitylimidazol-2-ylidene and dimesitylimidazolin-2-ylidene complexes of SnII have been prepared. Selected single-crystal X-ray structures are reported. The new compound
- Bantu, Bhasker,Pawar, Gajanan Manohar,Decker, Ulrich,Wurst, Klaus,Schmidt, Axel M.,Buchmeiser, Michael R.
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experimental part
p. 3103 - 3109
(2009/11/30)
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- Synthesis, structure and reactivity of samarium complexes supported by Schiff-base ligands
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Three tris(salicyladiminato) samarium complexes [3, 5 - Bu2t - 2 - (O) C6 H2 CH {double bond, long} NAr′]3 Sm (THF)n [Ar′ = 4 - ClC6 H4 (1), 4 -
- Li, Bangyu,Wang, Yaorong,Yao, Yingming,Zhang, Yong,Shen, Qi
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experimental part
p. 2409 - 2414
(2009/09/30)
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- 1,4,2-Diazaphospholidine-3,5-diones and related compounds: A lecture on unpredictability in catalysis
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1,4,2-diazaphospholidine-3,5-diones and related compounds and unpredictability in catalysis was studied. The five-membered ring species 4 6, which are all readily accessible by the McCormack reaction, optionally with subsequent hydrogenation, were selected for this study. The use of saturated species of type 4 (1-organyl-phospholanes) as catalysts led to a complete reverse in the selectivity of the reaction, in favor of the formation of the isocyanate trimers. Owing to the high activity of the corresponding P-oxides in carbodiimidization reactions, it can be assumed that the findings can be attributed to partial air oxidation of the trivalent phosphorus species applied. The symmetrical species 6, in total contrast to the other two members of the series, do not exhibit any catalytic activity with respect to isocyanates and instead react cleanly with two equivalents of isocyanate to effect the extrusion of 1,3-diene.
- Richter, Frank U.
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supporting information; experimental part
p. 5200 - 5202
(2009/12/24)
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- Palladium(0)-catalyzed trimerization of arylisocyanates into 1,3,5-triarylisocyanurates in the presence of diimines: A nonintuitive mechanism
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We show here that palladium(0) (dibenzylideneacetone) complexes bearing 1,10-phenanthroline constitute efficient catalysts for the cyclotrimerization of aromatic isocyanates. For the first time, the mechanism of this reaction has been investigated experimentally and theoretically with group 10 catalysts. This investigation provides a very consistent picture of the catalytic cycle. Notably, we establish that the reaction does not proceed by stepwise cycloadditions or ring insertions involving metallacyclic intermediates, as might have been anticipated. Rather, in our proposal, the initial steps of the mechanism resemble the chain-growth process operative during the anionic polymerization of isocyanates and feature charge-separated intermediates. These steps are then followed by ring closure on the metal center of the last intermediate formed to yield a seven-membered metallacycle that reductively eliminates the cyclotrimer and re-forms the active species. In addition, we conclusively show that the (known) palladacycles that could be isolated during the experimental investigations are not catalytic intermediates but result from catalyst deactivation. Thus, with Pd(0) diimine catalysts, the actual trimerization mechanism appears to be a blend between the two types of mechanisms proposed thus far for the oligomerization of heterocumulenes with very different catalysts. In conclusion, this work contributes to a better understanding of the reactivity of arylisocyanates in the vicinity of late group 10 metal centers in low oxidation state and sheds some light on the detrimental self-poisoning processes observed during the reductive carbonylation of nitroaromatic substrates catalyzed by related catalysts in non-nucleophilic media.
- Paul, Frederic,Moulin, Solenne,Piechaczyk, Olivier,Le Floch, Pascal,Osborn, John A.
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p. 7294 - 7304
(2008/02/06)
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- Novel reactions of arylmalonate carbanions. the reaction with phenyl isocyanate resulting in carbamates by 1,3-C→N migration of the ethoxycarbonyl group
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The reactions of carbanions of diethyl phenyl and 4-nitrophenylmalonates with phenyl isocyanate occur with 1,3-C→N migration of the ethoxycarbonyl group to form the corresponding adducts. The introduction of NO2 groups into the benzene ring of
- Linchenko,Krasnova,Petrovskii,Garbuzova,Khrustalev,Gololobov
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p. 1671 - 1674
(2008/09/18)
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- The performance of phthalimide-N-oxyl anion
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Alkali metal salts of phthalimide-N-oxyl, including Li, Na, and K were prepared and applied as novel selective catalysts to promote the cyclotrimerization of aryl and alkyl isocyanates. This paper is addressing these salts as a new class of organic nucleo
- Dekamin, Mohammad G.,Moghaddam, Firouz M.,Saeidian, Hamdollah,Mallakpour, Shadpour
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p. 1591 - 1595
(2007/10/03)
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- Sulfate catalysed multicomponent cyclisation reaction of aryl isocyanates under green conditions
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Sulfate anion, as a novel anionic catalyst, promotes the multicomponent cyclisation of aryl isocyantes to give heterocyclic symmetrical isocyanurates selectively under solvent-free conditions. The use of phase transfer catalysts reduces reaction times by
- Dekamin, Mohammad G.,Mallakpour, Shadpour,Ghassemi, Maryam
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p. 177 - 179
(2007/10/03)
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- Combination of sulfite anion and Phase Transfer Catalysts for green cyclotrimerization of aryl isocyanates
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The catalytic cyclotrimerization of aryl and alkyl isocyanates by the novel combination catalysts of sulfite ion and Phase Transfer Catalysts (PTCs), as selective anionic catalysts, has been investigated. The use of phase transfer catalyst features the ca
- Dekamin, Mohammad G.,Mallakpour, Shadpour,Ghassemi, Maryam
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p. 427 - 434
(2007/10/03)
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- N-heterocyclic carbenes as highly efficient catalysts for the cyclotrimerization of isocyanates
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(Chemical Equation Presented) A series of N-heterocyclic carbenes (NHCs) were evaluated as potential catalysts for the cyclotrimerization of isocyanates to afford isocyanurates. 1,3-Bis-(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2- ylidene (SIPr) was found to be a highly efficient catalyst for the cyclotrimerization of a variety of isocyanates.
- Duong, Hung A.,Cross, Michael J.,Louie, Janis
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p. 4679 - 4681
(2007/10/03)
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- First synthesis of a highly basic dendrimer and its catalytic application in organic methodology
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Sixteen OCH2CH2N3P(i-BuNCH 2CH2)3N substituents (A) containing the highly basic bicyclic azido-phosphine moiety shown, have been incorporated into the dendrimer [CH2CH2/sub
- Sarkar, Arunkanti,Ilankumaran, Palanichamy,Kisanga, Philip,Verkade, John G.
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p. 1093 - 1096
(2007/10/03)
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- Haloamidation of alkynes and related reactions using zirconacycles and isocyanates
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Zirconacyclopentenes reacted with isocyanates to give aza- or oxazirconacycles which were conveniently coverted into the corresponding haloamidation products of alkynes after halogenation. 1,4-Bistrimethylsilyl substituted zirconacyclopentadiene afforded a low yield of iodoamidation product, whereas zirconium-alkyne complexes stabilized with phosphine gave the iodoamidation products in moderate yields. On the other hand, zirconacyclopentanes reacted with isocyanates to give trimerization products of isocyanate, isocyanurates.
- Li, Yanzhong,Matsumura, Hiroshi,Yamanaka, Masamichi,Takahashi, Tamotsu
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p. 1393 - 1400
(2007/10/03)
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- Solvent-free efficient synthesis of symmetrical isocyanurates by a combination catalyst: Sodium saccharin and tetrabutylammonium iodide
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Combination of sodium saccharin and tetrabutylammonium iodide as a novel anionic catalyst system promotes selectively the trimerization of isocyanates to give symmetrical isocyanurates under solvent-free conditions. Springer-Verlag 2004.
- Matloubi Moghaddam, Firouz,Koozehgiri, Gholam R.,Dekamin, Mohammad G.
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p. 849 - 851
(2007/10/03)
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- Efficient and selective trimerization of aryl and alkyl isocyanates catalyzed by sodium p-toluenesulfinate in the presence of TBAI in a solvent-free condition
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Aryl and alkyl isocyanates have been efficiently converted into symmetrical trisubstituted aryl and alkyl isocyanurates, catalyzed by sodium p-toluenesulfinate on its own or in the presence of tetrabutylammonium iodide (TBAI), in a solvent-free condition.
- Moghaddam, Firouz Matloubi,Dekamin, Mohammad G.,Khajavi, Mohammad S.,Jalili, Seifollah
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p. 851 - 852
(2007/10/03)
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- Investigation into the reactivity of oxoniobocene complexes [Cp*2Nb(=O)R] (Cp=η5-C5Me5; R=H, OH, OMe) towards heterocumulenes: Formation of carbamato and thiocarbamato complexes and catalytic cyclization of PhNC
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The reaction of [Cp*2NbCl2] (Cp=η5-C5Me5) with KOH or Ba(OH)2·8H2O in THF was investigated under slightly modified conditions. In addition to the known complex [Cp*2Nb
- Blacque, Olivier,Brunner, Henri,Kubicki, Marek M.,Leblanc, Jean-Claude,Meier, Walter,Moise, Claude,Mugnier, Yves,Sadorge, André,Wachter, Joachim,Zabel, Manfred
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