- Selective Synthesis of β-Ketonitriles via Catalytic Carbopalladation of Dinitriles
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A practical, convenient, and highly selective method of synthesizing β-ketonitriles from the Pd-catalyzed addition of organoboron reagents to dinitriles has been developed. This method provides excellent functional-group tolerance, a broad scope of substrates, and the convenience of using commercially available substrates. The method is expected to show further utility in future synthetic procedures.
- Zeng, Ge,Liu, Jichao,Shao, Yinlin,Zhang, Fangjun,Chen, Zhongyan,Lv, Ningning,Chen, Jiuxi,Li, Renhao
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p. 861 - 867
(2021/01/09)
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- Catalytic Asymmetric Conjugate Protosilylation and Protoborylation of 2-Trifluoromethyl Enynes for Synthesis of Functionalized Allenes
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The Cu-catalyzed 1,4-protosilylation and protoborylation of trifluoromethyl-substituted conjugated enynes were developed to access functionalized homoallenylsilanes and homoallenylboronates. This protocol also provides a general method to synthesize optic
- Dai, Dong-Ting,Li, Qi,Liu, Zheng-Li,Ma, Wei-Wei,Xu, Yun-He,Yang, Chao,Zhao, Meng
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supporting information
(2020/02/22)
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- Solvent-free preparation method of di-substituted malononitrile derivative
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The invention relates to a solvent-free preparation method of a di-substituted malononitrile derivative. The solvent-free preparation method comprises: 1, adding malononitrile, aromatic aldehyde and dihydropyridine ester to a reaction test tube according
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Paragraph 0045; 0048-0053
(2019/05/11)
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- Titanium(III)-Catalyzed Reductive Decyanation of Geminal Dinitriles by a Non-Free-Radical Mechanism
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A titanium-catalyzed mono-decyanation of geminal dinitriles is reported. The reaction proceeds under mild conditions, tolerates numerous functional groups, and can be applied to quaternary malononitriles. A corresponding desulfonylation is demonstrated as well. Mechanistic experiments support a catalyst-controlled cleavage without the formation of free radicals, which is in sharp contrast to traditional stoichiometric radical decyanations. The involvement of two TiIII species in the C?C cleavage is proposed, and the beneficial role of added ZnCl2 and 2,4,6-collidine hydrochloride is investigated.
- Weweler, Jens,Younas, Sara L.,Streuff, Jan
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supporting information
p. 17700 - 17703
(2019/11/13)
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- A one-pot electrophilic cyanation–functionalization strategy for the synthesis of disubstituted malononitriles
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Malononitriles are valuable synthetic intermediates for many applications, including the synthesis of herbicides and other biologically active molecules, and the synthesis of chiral ligands for asymmetric catalysis. This article describes the development of a procedure for the conversion of primary nitriles to malononitriles using dimethylmalononitrile, a commercial, non-toxic, carbon-bound source of electrophilic cyanide. This procedure avoids the use of toxic cyanide or malononitrile as a starting material. This protocol is further applied to the dicyanation of benzyl Grignard reagents, generated from benzyl bromides, yielding fully functionalized malononitriles from a nitrile-free precursor.
- Mills, L. Reginald,Rousseaux, Sophie A.L.
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p. 4298 - 4306
(2019/05/22)
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- Cobalt-Catalyzed Enantioselective Negishi Cross-Coupling of Racemic α-Bromo Esters with Arylzincs
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The first cobalt-catalyzed enantioselective Negishi cross-coupling reaction, and the first arylation of α-halo esters with arylzinc halides, are disclosed. Employing a cobalt-bisoxazoline catalyst, various α-arylalkanoic esters were synthesized in excellent enantioselectivities and yields (up to 97 % ee and 98 % yield). A diverse range of functional groups, including ether, halide, thioether, silyl, amine, ester, acetal, amide, olefin and heteroaromatics is tolerated by this method. This method was suitable for gram-scale reactions, enabling the synthesis of (R)-xanthorrhizol with high enantiopurity. Radical clock experiments support the intermediacy of radicals.
- Liu, Feipeng,Zhong, Jiangchun,Zhou, Yun,Gao, Zidong,Walsh, Patrick J.,Wang, Xueyang,Ma, Sijie,Hou, Shicong,Liu, Shangzhong,Wang, Minan,Wang, Min,Bian, Qinghua
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supporting information
p. 2059 - 2064
(2018/02/14)
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- Ionic liquid as catalyst and solvent: the remarkable effect of a basic ionic liquid, [bmIm]OH on Michael addition and alkylation of active methylene compounds
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A basic ionic liquid, 1-methyl-3-butylimidazolium hydroxide, [bmIm]OH, catalyzes the Michael addition of active methylene compounds to conjugated ketones, carboxylic esters and nitriles. It further catalyzes the addition of thiols to α,β-acetylenic ketones and alkylation of 1,3-dicarbonyl and -dicyano compounds. The Michael addition to α,β-unsaturated ketones proceeds in the usual way, giving the monoaddition products, whereas addition to α,β-unsaturated esters and nitriles leads exclusively to the bis-addition products. The α,β-acetylenic ketones undergo double conjugate addition with thiols producing β-keto 1,3-dithio-derivatives. In the alkylation reaction the acyclic 1,3-diketones are monoalkylated, whereas cyclic ketones undergo dialkylation under identical conditions. All these reactions were carried out without any organic solvent. The ionic liquid can also be recycled.
- Ranu, Brindaban C.,Banerjee, Subhash,Jana, Ranjan
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p. 776 - 782
(2007/10/03)
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- Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
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Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
- Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
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p. 4433 - 4451
(2008/02/09)
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- A facile method for the construction of highly substituted acetonitriles and olefins. Malononitriles as acetonitrile carbanion and alkylidene dianion equivalents
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The use of malononitrile to facilitate the preparation of highly substituted nitriles, via reductive alkylation/addition, and olefins, via a combination of reductive addition and reductive elimination, is described.
- Tsai, Ting-Yueh,Shia, Kak-Shan,Liu, Hsing-Jang
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- Catalytic oxidative carbonylation of primary and secondary diamines to cyclic ureas. Optimization and substituent studies
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W(CO)6-catalyzed oxidative carbonylation of 1,3-propanediamine to the corresponding urea has been examined under a variety of conditions. Following optimization, the Thorpe-Ingold effect on ring closure was studied using 2,2-dialkyl-1,3-propanediamines. For the 2,2-dimethyl- and 2,2-dibutyl-1,3-propanediamines, the yields were increased significantly as compared to that of the unsubstituted case. The eight-membered cyclic urea 5-butyl-5-ethyl-1,3-diazepan-2-one (5f) was formed in 38% yield, while only trace amounts of the cyclic urea were produced from the parent 1,5-pentanediamine. In a study of secondary diamines, yields from the carbonylation of N,N′-dialkyl-2,2-dimethyl-1,3-propanediamines were lower than those obtained from the primary diamines. The main byproducts from secondary diamines were tetrahydropyrimidine derivatives formed from a competitive reaction of the substrate with the oxidant and base.
- Qian, Fang,McCusker, Jennifer E.,Zhang, Yue,Main, A. Denise,Chlebowski, Mary,Kokka, Michiyo,McElwee-White, Lisa
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p. 4086 - 4092
(2007/10/03)
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- Mono- vs. dialkylation of carbanions. Effects of absolute and relative acidity of the conjugate carbon acids in selectivity control
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The title problem was investigated in the reaction of the dibromide 1 with carbanions 2a-2g covering a range greater than 15 pK units in DMSO. It was found that the bis(monoalkylated) product 3 arises exclusively or predominantly from the carbanions 2d-2g derived from the less acidic carbon acids 7d-7g whereas the cyclic product of dialkylation 4 prevails in the reaction of the carbanions 2a-2c derived from the more acidic carbon acids 7a-7c. The alkylation selectivity thus depends critically on the absolute acidity of the carbon acid participating in the reaction. Rationale for this novel, and on basis of earlier studies unexpected finding is provided in terms of eqs. (1)-(4).
- Ridvan, Ludek,Zavada, Jiri
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p. 14793 - 14806
(2007/10/03)
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- Phase Transfer Catalysis without Solvent: Selective Mono- or Di-alkylation of Malononitrile
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Monoalkyl and symmetrical or unsymmetrical dialkylmalononitriles have been prepared selectively by phase transfer catalysis in the absence of solvent.Exclusive formation of a particular compound is achieved in all cases except for benzylmalononitrile 2f (79percent) and prop-2-ynylmalononitrile 2g (62percent).
- Diez-Barra, Enrique,Hoz, Antonio de la,Moreno, Andres,Sanchez-Verdu, Prado
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p. 2589 - 2592
(2007/10/02)
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- Solid-Liquid Phase Transfer Catalysis I. Benzylation of Malononitrile
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Benzylation of malononitrile has been carried out under solid-liquid phase-transfer catalysis conditions without solvent.The influence of different variables, such as type of base, addition of alumina, molar ratio of phase-transfer agent, temperature, tim
- Diez-Barra, E.,Hoz, A. de la,Moreno, A.,Sanchez-Verdu, P.
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p. 391 - 393
(2007/10/02)
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- Organic Synthesis using PTC: Part 7 - Reaction of Benzaldehyde with Malononitrile under Phase Transfer Catalysis
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Reaction of benzaldehyde (1) with malononitrile (2) under solid-liquid phase transfer (PT) conditions using K2CO3 as the base and triethylbenzylammonium chloride (TEBA) as catalyst furnishes compounds (3), (6) and (7) depending upon the reaction condition
- Singh, Paramjit,Aggarwal, Pawan
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p. 1029 - 1030
(2007/10/02)
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