- One-Pot Synthesis of Thiocarbamates
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An efficient isocyanide-based synthesis of S-thiocarbamates was discovered and thoroughly investigated. The new reaction protocol is a one-pot procedure and allows the direct conversion of N-formamides into thiocarbamates by initial dehydration with p-toluene sulfonyl chloride to the respective isocyanide and subsequent addition of a sulfoxide component. Contrary to recent literature, which also uses isocyanides as starting material, but with other sulfur reagents than sulfoxides, in this protocol, no isolation and purification of the isocyanide component is necessary, thus significantly decreasing the environmental impact and increasing the efficiency of the synthesis. The new protocol was applied to synthesize a library of sixteen thiocarbamates, applying four N-formamides and four commercially available sulfoxides. Furthermore, experiments were conducted to investigate the reaction mechanism. Finally, four norbornene-based thiocarbamate monomers were prepared and applied in controlled ring-opening metathesis polymerization (ROMP) reactions. The polymers were characterized by size-exclusion chromatography (SEC) and their properties were investigated utilizing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).
- Barther, Dennis,Malliaridou, Triantafillia,Meier, Michael A. R.,Moatsou, Dafni,Waibel, Kevin A.
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supporting information
p. 4508 - 4516
(2021/08/30)
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- A more sustainable and highly practicable synthesis of aliphatic isocyanides
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Synthesis protocols to convert N-formamides into isocyanides using three different dehydration reagents (i.e. p-toluenesulfonyl chloride (p-TsCl), phosphoryl trichloride (POCl3) and the combination of triphenylphosphane (PPh3) and iodine) were investigated and optimized, while considering the principles of green chemistry. Comparison of the yield and the E-factors of the different synthesis procedures revealed that, in contrast to the typically applied POCl3 or phosgene derivatives, p-TsCl was the reagent of choice for non sterically demanding aliphatic mono- or di-N-formamides (yields up to 98% and lowest E-factor 6.45). Apart from a significantly reduced E-factor, p-TsCl is cheap, offers a simplified reaction protocol and work-up, and is less toxic compared to other dehydration reagents. Thus, this procedure offers easier and greener access to aliphatic isocyanide functionalities.
- Waibel,Nickisch,M?hl,Seim,Meier
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supporting information
p. 933 - 941
(2020/02/21)
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- Facile, catalyst-free cascade synthesis of sulfonyl guanidines: Via carbodiimide coupling with amines
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An expeditious catalyst-free cascade coupling of N,N-dibromoarylsulfonamides with isonitriles and amines via carbodiimide intermediates has been developed. The protocol represents an elegant pathway for sulfonyl guanidines at room temperature within a short time with high yields and wide substrate scope. The carbodiimide intermediate could also be isolated in an appreciable yield.
- Hazarika, Debojit,Borah, Arun Jyoti,Phukan, Prodeep
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supporting information
p. 1418 - 1421
(2019/02/05)
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- Tandem reaction strategy of the Passerini/Wittig reaction based on the in situ capture of isocyanides: One-pot synthesis of heterocycles
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This paper reports the tandem reaction strategy of the Passerini/Wittig reaction based on the in situ capture of isocyanides. According to this strategy, plenty of isocyanides have been synthesized, which is immediately used for the tandem reaction of Passerini/Wittig reaction in one pot. Compared to the previous work, this strategy avoids the separation, purification, and storage of isocyanides, which prominently solves the problems of isocyanide-based multicomponent reaction such as: (a) The environmentally unfriendly (strong foul odor), (a) the labile of Isocyanides, (c) high toxicity of isocyanides. In the meantime, in order to expand the application scope of our strategy, 1H-isochromenes and 3H-2-benzoxepin-1-ones have also been synthesized, which undergoes four-step transformations in one-pot. In addition, a relatively credible reaction mechanism has also been proposed, based on a series of control experiments. Furthermore, preliminary testing was performed on biological activity of some obtained compounds; These results showed that the synthesized compounds exhibited certain activity over P. digitatum and P. italicum. 2019 Elsevier Science. All rights reserved.
- Liu, Ming-Guo,Liu, Na,Xu, Wen-Heng,Wang, Long
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p. 2748 - 2754
(2019/04/04)
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- Odorless Isocyanide Chemistry: One-Pot Synthesis of Heterocycles via the Passerini and Postmodification Tandem Reaction Based on the in Situ Capture of Isocyanides
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This paper reports the tandem reaction strategy of the Passerini/Staudinger/aza-Wittig reaction based on the in situ capture of isocyanides. According to this strategy, isocyanides are synthesized in situ and immediately work as the substrate for the Passerini reaction and postmodification tandem reaction in one pot. In addition, two types of new compounds, 5-oxo-3,5-dihydrobenzo[e][1,4]oxazepines and 6-oxo-5,6-dihydro-2H-1,4-oxazines, were synthesized using the tandem reaction strategy that includes five-step transformations in one pot.
- Liu, Na,Chao, Fei,Liu, Ming-Guo,Huang, Nian-Yu,Zou, Kun,Wang, Long
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p. 2366 - 2371
(2019/05/16)
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- Discovery of AG-120 (Ivosidenib): A First-in-Class Mutant IDH1 Inhibitor for the Treatment of IDH1 Mutant Cancers
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Somatic point mutations at a key arginine residue (R132) within the active site of the metabolic enzyme isocitrate dehydrogenase 1 (IDH1) confer a novel gain of function in cancer cells, resulting in the production of d-2-hydroxyglutarate (2-HG), an oncometabolite. Elevated 2-HG levels are implicated in epigenetic alterations and impaired cellular differentiation. IDH1 mutations have been described in an array of hematologic malignancies and solid tumors. Here, we report the discovery of AG-120 (ivosidenib), an inhibitor of the IDH1 mutant enzyme that exhibits profound 2-HG lowering in tumor models and the ability to effect differentiation of primary patient AML samples ex vivo. Preliminary data from phase 1 clinical trials enrolling patients with cancers harboring an IDH1 mutation indicate that AG-120 has an acceptable safety profile and clinical activity.
- Popovici-Muller, Janeta,Lemieux, René M.,Artin, Erin,Saunders, Jeffrey O.,Salituro, Francesco G.,Travins, Jeremy,Cianchetta, Giovanni,Cai, Zhenwei,Zhou, Ding,Cui, Dawei,Chen, Ping,Straley, Kimberly,Tobin, Erica,Wang, Fang,David, Muriel D.,Penard-Lacronique, Virginie,Quivoron, Cyril,Saada, Véronique,De Botton, Stéphane,Gross, Stefan,Dang, Lenny,Yang, Hua,Utley, Luke,Chen, Yue,Kim, Hyeryun,Jin, Shengfang,Gu, Zhiwei,Yao, Gui,Luo, Zhiyong,Lv, Xiaobing,Fang, Cheng,Yan, Liping,Olaharski, Andrew,Silverman, Lee,Biller, Scott,Su, Shin-San M.,Yen, Katharine
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supporting information
p. 300 - 305
(2018/04/20)
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- One-step synthesis of N, N′-substituted 4-imidazolidinones by an isocyanide-based pseudo-five-multicomponent reaction
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A pseudo-five-multicomponent reaction involving an isocyanide, a primary amine, two molecules of formaldehyde and water is reported, which gives N,N′-substituted 4-imidazolidinones when trifluoroethanol is used as the solvent. The reaction proceeds with good yields and with a wide variety of amines and isocyanides, providing an efficient new entry to these heterocycles. A preliminary study of the reaction mechanism suggests that trifluoroethanol, although acting as the solvent, is directly involved as a reagent in the reaction pathway.
- Attorresi, Cecilia I.,Bonifazi, Evelyn L.,Ramírez, Javier A.,Gola, Gabriel F.
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supporting information
p. 8944 - 8949
(2018/12/10)
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- 2-Isocyano glucose used in Ugi four-component reaction: An approach to enhance inhibitory effect against DNA oxidation
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The Ugi four-component-reaction (Ugi 4CR) allowed synthesizing bisamide from carboxylic acid, aldehyde, amine, and isocyanide in one-pot operation. However, introducing 2-isocyano glucose into the Ugi 4CR and investigating the inhibitory effects of Ugi adducts against radical-induced oxidation of DNA remained technical challenges. We herein applied 2-isocyano glucose (acetylation of hydroxy groups) to perform a catalyst-free Ugi 4CR at room temperature. The gallic, ferulic, caffeic, or p-hydroxybenzoic acids, aniline (or benzylamine and p-aminophenol), and formaldehyde acted as reagents. In the case of inhibiting DNA oxidations induced by 2,2’-azobis(2-amidinopropane hydrochloride) (AAPH), hydroxy radical, and Cu2+/glutathione, the Ugi adduct containing glucose moiety exhibited higher antioxidative activities than the structural analog without glucose moiety involved. It was also proved that high antioxidative property was owing to hydroxy groups in glucose moiety. Therefore, sugar-appended Ugi adducts might hold promising inhibitors for DNA oxidation.
- Zhao, Peng-Fei,Liu, Zai-Qun
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p. 458 - 466
(2017/05/05)
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- Synthesis and structure–activity relationship of α-keto amides as enterovirus 71 3C protease inhibitors
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α-Keto amide derivatives as enterovirus 71 (EV71) 3C protease (3Cpro) inhibitors have been synthesized and assayed for their biochemical and antiviral activities. structure–activity relationship (SAR) study indicated that small moieties were primarily tolerated at P1' and the introduction of para-fluoro benzyl at P2 notably improved the potency of inhibitor. Inhibitors 8v, 8w and 8x exhibited satisfactory activity (IC50= 1.32 ± 0.26 μM, 1.88 ± 0.35 μM and 1.52 ± 0.31 μM, respectively) and favorable CC50values (CC50> 100 μM). α-Keto amide may represent a good choice as a warhead for EV71 3Cproinhibitor.
- Zeng, Debin,Ma, Yuying,Zhang, Rui,Nie, Quandeng,Cui, Zhengjie,Wang, Yaxin,Shang, Luqing,Yin, Zheng
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supporting information
p. 1762 - 1766
(2016/12/22)
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- Efficient isocyanide-less isocyanide-based multicomponent reactions
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Isocyanides are the Jekyll and Hyde of organic chemistry allowing for extremely interesting transformations that are not only extremely odorous but also noxious. Therefore, an isocyanide-less isocyanide-based multicomponent reaction (IMCR) has been developed, and this protocol is expected to replace many of the old procedures in the future not only in IMCR but in other areas of organic chemistry as well.
- Neochoritis, Constantinos G.,Stotani, Silvia,Mishra, Bhupendra,D?mling, Alexander
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supporting information
p. 2002 - 2005
(2015/04/27)
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- Multicomponent cascade cycloaddition involving tropone, allenoate, and isocyanide: A rapid access to a 7,6,5-fused tricyclic skeleton
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Multicomponent cascade cycloaddition of tropone, allenoate, and isocyanide has been disclosed. This method allows for the rapid construction of a highly unusual tricyclic skeleton in an efficient manner. The proposed transformation proceeds through [8 + 2 + 1] cycloaddition, [1,5]-H shift, and cyclization followed by an alkoxy group migration process.
- Jia, Shuanglong,Su, Shikuan,Li, Chunju,Jia, Xueshun,Li, Jian
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supporting information
p. 5604 - 5607
(2015/02/19)
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- Odorless isocyanide chemistry: An integrated microfluidic system for a multistep reaction sequence
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Can't smell this: An integrated continuous-flow microfluidic setup enables in situ generation, extraction, separation, and reaction of foul-smelling isocyanides with little exposure to the surroundings. Isocyanides were generated by dehydration of the corresponding N-substituted formamides, and several representative isocyanide-based organic reactions were successfully performed. DIPEA=N,N-diisopropylethylamine. Copyright
- Sharma, Siddharth,Maurya, Ram Awatar,Min, Kyoung-Ik,Jeong, Guan-Young,Kim, Dong-Pyo
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supporting information
p. 7564 - 7568
(2013/07/26)
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- Efficient one-pot synthesis of unsymmetrical gold(I) N-heterocyclic carbene complexes and their use as catalysts
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Eleven different gold(I) complexes of new NHC ligands were prepared in excellent yield, demonstrating the versatility of the new route to NHC complexes. While the influence of electronically different ligands on the synthesis of the catalysts was small, the catalytic activities of the products differed significantly.
- Hashmi, A. Stephen K.,Yu, Yang,Rominger, Frank
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experimental part
p. 895 - 904
(2012/04/04)
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- Synthesis and evaluation of inhibitors of bacterial drug efflux pumps of the major facilitator superfamily
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Inhibitors of drug efflux pumps have great potential as pharmacological agents that restore the drug susceptibility of multidrug resistant bacterial pathogens. Most attention has been focused on the discovery of small molecules that inhibit the resistance nodulation division (RND) family drug efflux pumps in Gram-negative bacteria. The prototypical inhibitor of RND-family efflux pumps in Gram-negative bacteria is MC-207,110 (Phe-Arg-β-naphthylamide), a C-capped dipeptide. Here, we report that C-capped dipeptides inhibit two chloramphenicol-specific efflux pumps in Streptomyces coelicolor, a Gram-positive bacterium that is a relative of the human pathogen Mycobacterium tuberculosis. Diversity-oriented synthesis of a library of structurally related C-capped dipeptides via an Ugi four component reaction and screening of the resulting compounds resulted in the discovery of a compound that is threefold more potent as a suppressor of chloramphenicol resistance in S. coelicolor than MC-207,110. Since chloramphenicol resistance in S. coelicolor is mediated by major facilitator superfamily drug efflux pumps, our findings provide the first evidence that C-capped dipeptides can inhibit drug efflux pumps outside of the RND superfamily.
- Okandeji, Babajide O.,Greenwald, Daniel M.,Wroten, Jessica,Sello, Jason K.
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experimental part
p. 7679 - 7689
(2012/02/05)
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- Facile reaction of carboxylic acids with isonitriles in toluene
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Isonitriles react with low concentrations of carboxylic acids in toluene at 110 °C to give N-formylamides in yields generally above 70%. These concentrations can be obtained either by syringe pump addition of a toluene solution of the acid, or by using a suspension of the acid if it has limited solubility in toluene at room temperature.
- Polisar, Jason G.,Li, Ling,Norton, Jack R.
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supporting information; experimental part
p. 2933 - 2934
(2011/06/23)
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- Syntheses of spirocyclic oxindole-butenolides by using three-component cycloadditions of isocyanides, allenoates, and isatins
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Spiro workflow! Efficient syntheses of spirocyclic oxindole-butenolides from readily available isocyanides, allenoates, and isatins are disclosed (see scheme; R1=alkyl, aryl; R2=halide, nitro, methoxy; PG=protecting group). This protocol also allows the insertion of carbon monoxide into organic molecules without the aid of a transition-metal catalyst after the hydrolysis process. Copyright
- Li, Jian,Liu, Yuejin,Li, Chunju,Jia, Xueshun
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supporting information; experimental part
p. 7409 - 7413
(2011/08/05)
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- Synthesis of 4-Methyl-1,2,3-thiadiazole derivatives via ugi reaction and their biological activities
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The Ugi reaction is a green and rapid one-pot reaction for lead derivation. To develop novel candidate pesticides with diverse biological activities, two series of 4-methyl-1,2,3-thiadiazole derivatives containing active substructures of 3-chloro-4-methylphenyl or 3-fluoro-4-methylphenyl, respectively, were rationally designed and synthesized via Ugi reaction according to the principle of combinations of bioactive substructures. All of the structures of newly synthesized compounds were confirmed by proton nuclear magnetic resonance and high-resolution mass spectrometry. Biological activities of the target compounds including fungicide activity, antivirus activity in vitro and in vivo, and systemic acquired resistance were evaluated systematically. The results indicated that derivatives containing 3-(trifluoromethyl)phenyl and 2-methylphenyl possessed a potential wide spectrum of fungicidal activity. Derivatives containing 3-(trifluoromethyl)phenyl and 4-hydroxyphenyl possessed good potential direct antivirus activities against tobacco mosaic virus (TMV) in vitro, and the replacement of Cl atom by F atom improved their direct inhibition activities against TMV in vitro. Derivatives containing phenyl, 2-(trifluoromethyl)phenyl, 3-(trifluoromethyl)phenyl, 3-nitrophenyl, 4-nitrophenyl, 2-methylphenyl, and 4-hydroxyphenyl possessed good potential bioactivities in vivo including protection, inactivation, curative, and induction activities against TMV. These studies indicate that the newly synthesized 4-methyl-1,2,3-thiadiazole derivatives possessed good potential bioactivities, and a combination of bioactive substructures via Ugi reaction was an effective way to find bioactive compounds for novel pesticide development.
- Zuo, Xiang,Mi,Fan, Zhijin,Zheng, Qingxiang,Zhang, Haike,Wang, Huan,Yang, Zhikun
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experimental part
p. 2755 - 2762
(2011/07/31)
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- Synthesis of sugar-derived isoselenocyanates, selenoureas, and selenazoles
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Aryl, alkyl, and sugar-derived isoselenocyanates were prepared by a one-pot procedure starting from the corresponding formamides, using triphosgene as a dehydrating agent, triethylamine, and black selenium powder. The preparation of sugar selenoureas by coupling of O-protected sugar-derived isoselenocyanates with different amines, and by coupling of unprotected glycopyranosyl amines with phenyl isoselenocyanate was also accomplished. The synthesis of a glucopyranos-2-yl-selenazole starting from O-protected 2-amino-2-deoxy-d-glucose by coupling with benzoyl isoselenocyanate, Se-alkylation with phenacyl bromide, and acid-catalyzed dehydration is also reported. Unprotected N-(β-d-glucopyranosyl)-N′-phenylselenourea was transformed into a 1,2-trans-fused bicyclic isourea upon treatment with aqueous hydrogen peroxide; the same isourea was prepared by a one-pot three-step procedure from β-d-glycopyranosylamine by thiophosgenation, coupling with aniline, and HgO-mediated desulfurization.
- López, óscar,Maza, Susana,Ulgar, Víctor,Maya, Inés,Fernández-Bola?os, José G.
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experimental part
p. 2556 - 2566
(2009/08/08)
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- A polymer-supported [1,3,2]oxazaphospholidine for the conversion of isothiocyanates to isocyanides and their subsequent use in an ugi reaction.
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The design and synthesis of a new polymer supported reagent for the clean conversion of isothiocyanates to isocyanides under microwave conditions was accomplished. The structurally diverse isocyanides generated were used in an Ugi 3CC, allowing the rapid generation of 2-isoindolinone-7-carboxamide analogues.
- Ley, Steven V,Taylor, Stephen J
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p. 1813 - 1816
(2007/10/03)
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- Solid phase-mediated synthesis of isonitriles
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Supported sulfonyl chlorides and microwave irradiation are an efficient combination for isonitrile synthesis.
- Launay, Delphine,Booth, Susan,Clemens, Ian,Merritt, Andrew,Bradley, Mark
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p. 7201 - 7203
(2007/10/03)
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- Kinetics and mechanism of acid-catalyzed hydrolysis of cyclohexyl isocyanide and pKa determination of N-cyclohexylnitrilium ion
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A novel mechanism for acid-catalyzed hydrolysis of cyclohexyl isocyanide is proposed. It is specific acid/general base catalysis, involving a fast, pre-equilibrium C-protonation of the isocyanide, followed by a rate-determining attack of water on the electron-deficient carbon of the protonated isocyanide. The pKa of N-cyclohexylnitrilium ion was determined to be 0.86±0.05.
- Sung, Kuangsen,Chen, Chao-Chih
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p. 4845 - 4848
(2007/10/03)
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- 2-Chloro-1,3-dimethylimidazolinium chloride. 1. A powerful dehydrating equivalent to DCC
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2-Chloro-1,3-dimethylimidazolinium chloride (DMC) (3) can act as a powerful dehydrating agent, replacing DCC (1) under nearly neutral conditions. Its application to acylation and dehydration is described.
- Isobe, Toshio,Ishikawa, Tsutomu
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p. 6984 - 6988
(2007/10/03)
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- Electrochemical generation of alkyl and aryl isocyanides
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An efficient and widely applicable reagent-free method for the synthesis of alkyl and aryl isocyanides has been established. The electrochemical reduction of alkyl and aryl carbonimidoyl dichlorides under constant cathode potential leads to the corresponding isocyanides in almost quantitative yields. The availability of the starting materials, the mildness of the reaction conditions as well as the easy isolation of products are noteworthy, advantageous features of the procedure.
- Guirado, Antonio,Zapata, Andres,Gomez, Jesus L.,Trabalon, Luis,Galvez, Jesus
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p. 9631 - 9640
(2007/10/03)
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- Dehydration of formamides using the Burgess Reagent: A new route to isocyanides
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The Burgess Reagent readily converts formamides into isocyanides in high yields and is particularly effective for substrates containing halide sensitive trimethylsilyl ether groups.
- Creedon, Siobhan M.,Crowley, H. Kevin,McCarthy, Daniel G.
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p. 1015 - 1017
(2007/10/03)
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- A Convenient and High Yielding Procedure for the Preparation of Isoselenocyanates. Synthesis and Reactivity of O-Alkylselenocarbamates.
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A high yielding one pot procedure for the preparation of isoselenocyanate from the corresponding formamide is reported.Various aromatic and aliphatic primary amines were employed in order to prepare the isoselenocyanates to establish the generality of the procedure.O-Alkylselenocarbamates of various primary, secondary and tertiary alcohols were synthesized and their stability and comparative reactivity were studied.Radical deoxygenation of the selenocarbamate of a secondary and a tertiary alcohol was accomplished under various conditions.
- Barton, Derek H. R.,Parekh, Shyamal I.,Tajbakhsh, Mahmoud,Theodorakis, Emmanouil A.,Tse, Chi-Lam
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p. 639 - 654
(2007/10/02)
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- ELECTROCHEMICAL REDUCTION OF CARBONIMIDOYL DICHLORIDES. A NEW METHOD FOR THE PREPARATION OF ISOCYANIDES
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The cathodic reduction of carbonimidoyl dichlorides provides a new, mild and free-reagent method for the preparation of isocyanides in almost quantitative yields.
- Guirado, Antonio,Zapata, Andres,Fenor, Manuel
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p. 4779 - 4782
(2007/10/02)
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- iron(II) Compounds with Isocyanides as Axial Ligands
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Aliphatic and aromatic monodentate isocyanides RNC (R = t-Bu, c-Hx, substituted Ph) react with iron(II) (TPyPFe) to form the corresponding diaxially substituted iron(II) compounds TPyPFe(RNC)2 1a-8a.The spectroscopic data and thermal properties of the complexes are described and compared with the analogous PcFe(CNR)2 compounds 1b-8b.
- Hanack, Michael,Thies, Ruediger
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p. 1225 - 1230
(2007/10/02)
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- Reaction of the Metallacycle n)S>(1+) with Nucleophiles. X-Ray Crystal Structures of the Comlexes n)S>SO3CF3 and SC(FeLn)S>n = Fe(cp)(CO)2, cp = η-C5H5>
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Reactions of the metallacyclic cation n)S>(1+)n = Fe(cp)(CO)2, cp = η-C5H5> with nucleophilic agents have been investigated.The results indicate that the carbene carbon atom bonded to the endocyclic iron is the site of addition of all the nucleophiles examined.Primary amines NH2R (R = Me, C6H11, or n-Bu) form neutral isocyanide derivatives n> with opening of the FeC2S2 ring, whereas secondary amines such as NHR2 (R = Me or Et) or HN(CH2)nCH2 (n = 3 or 4) produce stable cationic cyclic aminothiocarbenes.The structure of one of these, n)S>SO3CF3, has been determined by X-ray diffraction a = 11.570(2), b = 12.242(2), c = 10.552(2) Angstroem, α = 104.60(2), β = 87.51(1), γ = 117.24(2) deg, Z = 2, and space group P1>.The cation contains the five-membered planar ring FeSCSC with the Fe(cp)(CO)2 and NC5H10 groups bonded to the carbon atoms.The C(carbene)-N interaction exhibits strong double-bond character , typical for an iminium cation.Methanethiol, Li(BHEt3), and KCN yield neutral n)S> (X = SMe, H, or CN).In the hydride addition an isomeric mixture has been ascertained by i.r. and n.m.r. spectra, whereas the cyanide ion adds steroselectively at the prochiral carbene centre to form only one diastereoisomer whose steric nature has been determined by X-ray diffraction a = 6.894(2), b = 10.057(1), c = 14.520(2) Angstroem, α = 96.00(2), β = 96.17(1), γ = 106.31(1) deg, Z = 2, and space group P1>.In this derivative the FeSCSC ring undergoes substantial changes because the iron-bonded carbon atom becomes four-co-ordinate with loss of its carbenic character and significant out-of-plane displacement.A comparative analysis of the relevant geometric features of all the members of this family is reported.Propane-1,3-dithiol produces the neutral spirocyclic SC(FeLn)S> which shows equivalence of the two diastereotopic SCH2 carbons in the high-temperature 13C n.m.r. spectrum and splitting of ν(CO) in the i.r. spectrum.These spectroscopic features are discussed and interpreted.
- Busetto, Luigi,Zanotti, Valerio,Albano, Vincenzo G.,Braga, Dario,Monari, Magda
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p. 1067 - 1074
(2007/10/02)
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- Electrochemistry of 2-Bromo-2-methylpropanamides. Reduction Mechanism and Cyclocoupling Reaction with Amide Solvents
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The electrochemical reduction of series of secondary and tertiary α-bromoisobutyramides has been studied in dipolar aprotic solvents.A carbanion is formed at the mercury electrode as a consequence of two-electron C-Br bond cleavage.Voltammetry and macroelectrolysis point to a self-protonation mechanism, the carbanion undergoing protonation by a parent molecule to yield the isobutyramide.Concurrently, tertiary 2-bromoamides undergo 1,2-elimination to yield an αβ-unsaturated amide, while secondary 2-bromoamides are deprotonated at the nitrogen atom, affording a bromo-containing anion.The decay of the latter is strongly dependent on the solvent and the substituent at nitrogen.In acetonitrile, elimination and fragmentation products are identified in the electrolysed solution.On the other hand, in N,N-dimethylformamide or N,N-dimethylacetamide, the bromo-containing anion is eventually cyclocondensed onto the carbonyl group of the amide solvent, to yield an oxazolidin-4-one derivative.Preliminary data suggest that an analogous cyclocoupling reaction takes place when the reduction is carried out in 1-methyl-2-pyrrolidone.
- Maran, Flavio,Vianello, Elio,D'Angeli, Ferruccio,Cavicchioni, Giorgio,Vecchiati, Giorgio
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- DI-2-PYRIDYL SULFITE. A NEW USEFUL REAGENT FOR THE PREPARATION OF N-SULFINYLAMINES, NITRILES, ISOCYANIDES, AND CARBODIIMIDES UNDER MILD CONDITIONS
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Di-2-pyridyl sulfite is a very useful reagent for the preparation of N-sulfinylamines, nitriles, isocyanides, and carbodiimides in high yields under essentially neutral conditions.
- Kim, Sunggak,Yi, Kyu Yang
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p. 1925 - 1928
(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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- DEOXYGENATION OF ISOCYANATES TO ISONITRILES; A MECHANISTIC STUDY BY NUCLEAR MAGNETIC RESONANCE
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Carbon-13 NMR has been used to show that the deoxygenation of isocyanates to isonitriles with t-butyldiphenylsilyl lithium proceeds via the intermediates (7 and 8).The silyl carboxamide (1) can be isolated but is thermally unstable rearranging to a mixture of silyl formamides (2).The spectroscopic properties of the silyl carboxamide (1) were found to be substantially different from those previously claimed for such compounds.
- Baldwin, Jack E.,Derome, Andrew E.,Riordan, Peter D.
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p. 2989 - 2994
(2007/10/02)
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- 1,3-Acyl Migration in Carbonic Acid Derivatives - Synthesis of S-Polyhalogenoalkyl N-Acyl-N-aryl(alkyl)thiocarbamates
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Aryl(alkyl)iminochloromethyl polyhalogenoalkyl sulphides react with carboxylic acids to give S-polyhalogenoalkyl N-acyl-N-aryl(alkyl)thiocarbamates, which have not been synthesized by other routes.By analogy with known 1,3 rearrangements, the reaction appears to involve a nucleophilic substitution followed by a new type of 1,3-acyl migration.Similarly, with sodium azide 1-methyl- and 1-phenyl-5-trichloromethylthiotetrazoles are also obtained.
- Galli, Remo,Palla, Ottorino,Gozzo, Franco
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p. 2813 - 2818
(2007/10/02)
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- A new Method for the Reduction of Isocyanates to Isocyanides
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Both diphenyl-t-butylsilyl-lithium and trichlorosilane-triethylamine reduce isocyanates to isocyanides in high yield under mild conditions.
- Baldwin, Jack E.,Bottaro, Jeffrey C.,Riordan, Peter D.,Derome, Andrew E.
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p. 942 - 943
(2007/10/02)
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- Deoxygenation and Desulfurization of Organic Compounds via Transition Metal Atom Cocondensation
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Reactions resulting from the cocondensation of transition metal atoms with a variety of oxygen- and sulfur-containing organic compounds are surveyed.Alkenes are the major or exclusive volatile products when epoxides are reacted with Ti, V, Cr, Co, and Ni atoms. 2,6-Dimethylpyridine-N-oxide and dimethyl sulfoxide undergo deoxygenation upon cocondensation with chromium, but diisopropyl ether and decyl methyl ether do not.Dibenzyl ether yields bis(η6-dibenzyl ether)chromium(0) with Cr atoms, but dibenzyl sulfide undergoes desulfurization.Cyclohexanone and cycloheptanone afford low yields of reductive coupling and aldol products when cocondensed with Cr, Co, and Ni atoms.Nitro- and nitrosoarenes are deoxygenated to coupled azo and azoxy products with Cr atoms.Carbazole (3) is obtained from 2-nitrosobiphenyl, implicating nitrene or nitrenoid intermediates.Whereas isocyanides are not formed from isocyanates and metal atoms, they are produced when isothiocyanates are cocondensed with Cr and V atoms.
- Togashi, Shigeo,Fulcher, John G.,Cho, Bong Rae,Hasegawa, Minoru,Gladysz, J.A.
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p. 3044 - 3053
(2007/10/02)
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