- Crystal structure and DFT studies of 4-methyl-N-(1-phenylethyl)-N=-(1-phenylethylidene)benzenesulfonohydrazide: Evidence of a carbene insertion in the formation of acetophenone azine from acetophenone p-Toluensulfonylhydrazone
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The crystal structure of 4-Methyl-N-(1-phenylethyl)-N=-(1-phenylethylidene) benzene sulfonohydrazide is disclosed, which is obtained from direct reaction between acetophenone tosylhydrazone and potassium tert-butoxide. Reaction mechanisms and the corresponding energy barriers were assessed through DFT calculations at the B3LYP/6-31G(d,p) level of theory and showed that this compound plays an important role as an intermediate in the formation of acetophenone azine from acetophenone p-Toluensulfonylhydrazone through a carbene insertion on this last compound.
- Valencia, Rocío A.,Apolonio, Victor M.,Caballero-García, Guillermo,Martínez-Otero, Diego,Barroso-Flores, Joaquín,Cuevas-Ya?ez, Erick
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Read Online
- Gold(I) complexes bearing ring-fused benzoxazine-derived triazolylidenes and their use in C–N bond-forming processes
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We report the synthesis and full characterization of a novel series of ring-fused benzoxazine-derived triazolium salts (1a–c) and their corresponding triazolylidene gold(I) complexes (2a–c). All new compounds were fully characterized by means of 1H and 13C NMR spectroscopy, elemental analyses, and mass spectroscopy and in the case of triazoliums 1a and 1b by single-crystal X-ray diffraction. The new triazolylidene gold complexes (2a–c) were tested as precatalysts in the hydroamination and hydrohydrazination of terminal alkynes employing aniline derivatives and hydrazine as nitrogen sources, respectively.
- Campos-Dominguez, Emmanuel,Vasquez-Perez, Jose,Rojas-Lima, Susana,Lopez-Ruiz, Heraclio,Mendoza-Espinosa, Daniel
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- Synthesis of Sterically Hindered Primary Amines by Concurrent Tandem Photoredox Catalysis
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Primary amines are an important structural motif in active pharmaceutical ingredients (APIs) and intermediates thereof, as well as members of ligand libraries for either biological or catalytic applications. Many chemical methodologies exist for amine synthesis, but the direct synthesis of primary amines with a fully substituted α carbon center is an underdeveloped area. We report a method which utilizes photoredox catalysis to couple readily available O-benzoyl oximes with cyanoarenes to synthesize primary amines with fully substituted α-carbons. We also demonstrate that this method enables the synthesis of amines with α-trifluoromethyl functionality. Based on experimental and computational results, we propose a mechanism where the photocatalyst engages in concurrent tandem catalysis by reacting with the oxime as a triplet sensitizer in the first catalytic cycle and a reductant toward the cyanoarene in the second catalytic cycle to achieve the synthesis of hindered primary amines via heterocoupling of radicals from readily available oximes.
- Nicastri, Michael C.,Lehnherr, Dan,Lam, Yu-Hong,Dirocco, Daniel A.,Rovis, Tomislav
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supporting information
p. 987 - 998
(2020/01/31)
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- Palladium-Catalyzed Regioselective Acylation of Diazines with Toluenes: A New Approach to the Synthesis of ortho-Diacylbenzenes
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A highly efficient and practical procedure for chemo- and regioselective synthesis of ortho-diacylbenzenes through Pd-catalyzed oxidative C–H bond activation has been developed. Using this method, a variety of ortho-diacylbenzenes were prepared in moderate to good yields, by direct acylation of diazines with toluene derivatives as acylation source. Ortho-diacylbenzenes may be used as precursors in synthesis of pharmaceuticals and agrochemicals.
- Afaridoun, Hadi,Kianmehr, Ebrahim,Seifinoferest, Behnoush
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supporting information
(2020/08/13)
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- Light-enabled metal-free pinacol coupling by hydrazine
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Efficient carbon-carbon bond formation is of great importance in modern organic synthetic chemistry. The pinacol coupling discovered over a century ago is still one of the most efficient coupling reactions to build the C-C bond in one step. However, traditional pinacol coupling often requires over-stoichiometric amounts of active metals as reductants, causing long-lasting metal waste issues and sustainability concerns. A great scientific challenge is to design a metal-free approach to the pinacol coupling reaction. Herein, we describe a light-driven pinacol coupling protocol without use of any metals, but with N2H4, used as a clean non-metallic hydrogen-atom-transfer (HAT) reductant. In this transformation, only traceless non-toxic N2 and H2 gases were produced as by-products with a relatively broad aromatic ketone scope and good functional group tolerance. A combined experimental and computational investigation of the mechanism suggests that this novel pinacol coupling reaction proceeds via a HAT process between photo-excited ketone and N2H4, instead of the common single-electron-transfer (SET) process for metal reductants.
- Qiu, Zihang,Pham, Hanh D. M.,Li, Jianbin,Li, Chen-Chen,Castillo-Pazos, Durbis J.,Khaliullin, Rustam Z.,Li, Chao-Jun
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p. 10937 - 10943
(2019/12/23)
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- Unprecedented synthesis of symmetrical azines from alcohols and hydrazine hydrate using nickel based NNN-pincer catalyst: An experimental and computational study
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Azines are having widespread applications in both industry as well as synthetic chemistry. Thus new catalytic synthetic protocols are desirable as they are greener alternatives than traditional methods of synthesis. Thus, herein a novel earth abundant nickel based NNN-pincer catalyst Ni(BPEA)(Cl2) is synthesized for the first time for the direct transformation of alcohols and hydrazine hydrate into symmetrical azines. This catalytic reaction is accompanied by dehydrogenative coupling of alcohols and hydrazine hydrate and is carried out in presence of a base. Theoretical calculations supported by experimental evidence have been performed for understanding the mechanistic insights of the reaction.
- Shiekh, Bilal Ahmad,Kaur, Damanjit,Godara, Sachin Kumar
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- Cp*Co(iii)-catalyzed annulation of azines by C-H/N-N bond activation for the synthesis of isoquinolines
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Herein, an efficient, atom economic and external oxidant free approach has been disclosed for the synthesis of isoquinolines. Azines were employed for annulation reactions with alkynes via sequential C-H/N-N bond activation using an air-stable cobalt catalyst. The method takes advantage of the incorporation of both the nitrogen atoms of azines into the desired isoquinoline products, offering the highest atom economy. In addition, the developed protocol works under external oxidant as well as silver salt free conditions. Furthermore, the established methodology features a relatively broad substrate scope with high product yields and scalability up to the gram level.
- Deshmukh, Dewal S.,Yadav, Prashant A.,Bhanage, Bhalchandra M.
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supporting information
p. 3489 - 3496
(2019/04/14)
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- Rapid and Atom Economic Synthesis of Isoquinolines and Isoquinolinones by C–H/N–N Activation Using a Homogeneous Recyclable Ruthenium Catalyst in PEG Media
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Herein, we report an atom-efficient, rapid, green, and sustainable approach to synthesize isoquinolines and isoquinolinones using a homogeneous recyclable ruthenium catalyst in PEG Media assisted by microwave energy. Dibenzoylhydrazine was used for C–H/N–N activation reactions for the first time in combination with ketazine as oxidizing directing groups for annulation reactions with internal alkynes. The developed protocol is environmentally benign due to significantly shortened times with an easy extraction method, higher atom economy, external oxidant and silver or antimony salt free conditions, applicability to a gram scale synthesis, use of biodegradable solvent and wide substrate scope with higher product yields. Moreover, it is worth noting that the established methodology allowed reuse of the catalytic system for up to five successive runs with minimal loss in activity.
- Deshmukh, Dewal S.,Gangwar, Neha,Bhanage, Bhalchandra M.
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supporting information
p. 2919 - 2927
(2019/05/10)
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- A process for preparing 1, 2 - double-(1 - aryl alkyl methylene) method of the hydrazine compound
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The present invention discloses method for preparing a 1,2-bis(1-aralkyl methylene) hydrazine compound. The method comprises the following steps of: dissolving benzene sulfonyl hydrazone into a CH3CN solvent; then adding ammonium persulfate and cesium carbonate to react for 6hours under a condition of 100 DEG C; after the reaction is ended, performing extraction and column chromatographic separation, thereby obtaining the 1,2-bis(1-aralkyl methylene) hydrazine compound. According to the method, ammonium persulfate with a low price is used as a catalyst to catalyze benzene sulfonyl hydrazone to generate degradation reaction; the reaction conditions are mild; the reaction time is short; a post-treatment process is simple; the reaction product is low; and the product yield is high. The 1,2-bis(1-aralkyl methylene) hydrazine compound can be used as a useful synthesis intermediate, and has potential pharmaceutical activity and a wide application.
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Paragraph 0023; 0024; 0025; 0026; 0027; 0028; 0029-0032
(2017/07/21)
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- Cs2CO3-mediated decomposition of N-tosylhydrazones for the synthesis of azines under mild conditions
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Abstract: A facile, environmentally and efficient Cs2CO3-mediated decomposition of N-tosylhydrazones reaction has been developed for the synthesis of functionalized azines under mild conditions. This method offers broad substrate scope, occurs as additive-free, without strong base conditions, utilizes readily available reactants, and forms products in good to high yields. Graphical Abstract: [Figure not available: see fulltext.]
- Luo, Zai-Gang,Liu, Peng,Fang, Yu-Yu,Xu, Xue-Mei,Feng, Cheng-Tao,Li, Zhong,Zhang, Xiao-Mei,He, Jie
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p. 1139 - 1148
(2017/02/10)
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- Metal-Free [2 + 1 + 2]-Cycloaddition of Tosylhydrazones with Hexahydro-1,3,5-triazines to Form Imidazolidines
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A novel protocol toward imidazolidines has been accomplished using tosylhydrazones and hexahydro-1,3,5-triazines as the substrates under metal-free reaction conditions. Importantly, the role of LiOtBu has been confirmed not only to release the diazo but also to promote the cycloaddition. Further mechanistic investigations reveal that the reaction proceeds through a stepwise [2 + 1 + 2] process.
- Liu, Pei,Xu, Guangyang,Sun, Jiangtao
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supporting information
p. 1858 - 1861
(2017/04/11)
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- Visible-Light-Promoted AuI to AuIII Oxidation in Triazol-5-ylidene Complexes
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Reaction of triazolium precursors [MIC(CH2)n- H+]I? (n=1–3) with potassium hexamethyldisilazane (KHMDS) and AuCl(SMe2) generates the gold(I) complexes of the type MIC(CH2)n?AuI. Visible light exposure of the latter complexes promotes a spontaneous disproportionation process rendering gold(III) complexes of the type [{MIC(CH2)n}2?AuI2]+I?. Both the AuI and AuIII complex series were tested in the catalytic hydrohydrazination of terminal alkynes using hydrazine as nitrogen source.
- Mendoza-Espinosa, Daniel,Rendón-Nava, David,Alvarez-Hernández, Alejandro,Angeles-Beltrán, Deyanira,Negrón-Silva, Guillermo E.,Suárez-Castillo, Oscar R.
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supporting information
p. 203 - 207
(2017/02/05)
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- Ancillary ligand-free copper catalysed hydrohydrazination of terminal alkynes with NH2NH2
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An efficient and selective Cu-catalysed hydrohydrazination of terminal alkynes with parent hydrazine is reported. The methodology tolerates a broad range of functional groups, allows for the synthesis of symmetrical and unsymmetrical azines, and can be extended to hydrazine derivatives and amines.
- Peltier, Jesse L.,Jazzar, Rodolphe,Melaimi, Mohand,Bertrand, Guy
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supporting information
p. 2733 - 2735
(2016/02/19)
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- Acid Is Key to the Radical-Trapping Antioxidant Activity of Nitroxides
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Persistent dialkylnitroxides (e.g., 2,2,6,6-tetramethylpiperidin-1-oxyl, TEMPO) play a central role in the activity of hindered amine light stabilizers (HALS)-additives that inhibit the (photo)oxidative degradation of consumer and industrial products. The accepted mechanism of HALS comprises a catalytic cycle involving the rapid combination of a nitroxide with an alkyl radical to yield an alkoxyamine that subsequently reacts with a peroxyl radical to eventually re-form the nitroxide. Herein, we offer evidence in favor of an alternative reaction mechanism involving the acid-catalyzed reaction of a nitroxide with a peroxyl radical to yield an oxoammonium ion followed by electron transfer from an alkyl radical to the oxoammonium ion to re-form the nitroxide. In preliminary work, we showed that TEMPO reacts with peroxyl radicals at diffusion-controlled rates in the presence of acids. Now, we show that TEMPO can be regenerated from its oxoammonium ion by reaction with alkyl radicals. We have determined that this reaction, which has been proposed to be a key step in TEMPO-catalyzed synthetic transformations, occurs with k ～ 1-3 × 1010 M-1 s-1, thereby enabling it to compete with O2 for alkyl radicals. The addition of weak acids facilitates this reaction, whereas the addition of strong acids slows it by enabling back electron transfer. The chemistry is shown to occur in hydrocarbon autoxidations at elevated temperatures without added acid due to the in situ formation of carboxylic acids, accounting for the long-known catalytic radical-trapping antioxidant activity of TEMPO that prompted the development of HALS.
- Haidasz, Evan A.,Meng, Derek,Amorati, Riccardo,Baschieri, Andrea,Ingold, Keith U.,Valgimigli, Luca,Pratt, Derek A.
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supporting information
p. 5290 - 5298
(2016/05/19)
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- Nitrogen activation and conversion method promoted by divalent rare earth iodine compound
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The invention belongs to the technical field of organic chemical synthesis, and particularly relates to a method for activating and converting nitrogen through a divalent rare earth compound. A divalent rare earth diodide is used as a reducing agent, a solvent is added in, the mixture reacts with nitrogen, then a hydrogen source is added in, and then the mixture reacts with an aldehyde or ketone compound to obtain an azine or pyridazine compound. According to the method, the nitrogen is activated and converted into the organic compound containing nitrogen on the mild condition. Compared with a classical ammonia synthesis path, strict reaction conditions such as high temperature, high pressure and ammonia oxidation are avoided, and the method is of great significance in developing the new technology of nitrogen molecule activation and broadening the application range of rare earth metal in organic synthesis.
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Paragraph 0021; 0022
(2016/12/01)
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- Mesoionic Carbene-Gold(I) Catalyzed Bis-Hydrohydrazination of Alkynes with Parent Hydrazine
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A novel synthetic route gives access to mesoionic carbene and cyclopropenylidene supported gold chloride complexes. The corresponding cationic MIC-gold complex obtained by chloride abstraction allows for the first transition metal-catalyzed functionalization of both nitrogens of parent hydrazine.
- Tolentino, Daniel R.,Jin, Liqun,Melaimi, Mohand,Bertrand, Guy
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p. 2139 - 2142
(2015/10/05)
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- Facile one-pot synthesis of 1,3,5-trisubstituted pyrazoles from α,β-enones
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A practical and efficient one-pot synthesis of 1,3,5-trisubstituted pyrazoles from α,β-enones and arylhydrazine hydrochlorides has been developed. The pyrazoles were formed via a tandem formation of the corresponding pyrazolines and an acid-catalyzed aerobic oxidation process.
- Yu, Jin,Kim, Ko Hoon,Moon, Hye Ran,Kim, Jae Nyoung
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p. 1692 - 1696
(2014/07/07)
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- Rhodium-catalyzed synthesis of isoquinolines and indenes from benzylidenehydrazones and internal alkynes
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A new route is presented for the selective assembly of isoquinolines and indenes by rhodium-catalyzed tandem cyclization of benzylidenehydrazones with internal alkynes. This method involves the selective cleavage of the N-N bond and the C=N bonds and is dependent on the substituents of the benzylidenehydrazone.
- Huang, Xiao-Cheng,Yang, Xu-Heng,Song, Ren-Jie,Li, Jin-Heng
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p. 1025 - 1031
(2014/03/21)
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- Monohydrocyanation of symmetrical azines using potassium hexacyanoferrate(II) as an environmentally friendly cyanide source
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The monohydrocyanation of symmetrical azines to synthesize α-hydrazinonitriles using potassium hexacyanoferrate(II) as cyanide source and benzoyl chloride as a promoter under catalyst-free conditions is described. The advantages of this protocol are the environmentally friendly cyanide source, high yield, and simple work-up procedure. Georg Thieme Verlag Stuttgart New York.
- Hu, Xiaochun,Li, Hongbo,Yang, Jingya,Li, Zheng
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supporting information
p. 1786 - 1790
(2014/08/05)
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- Base and solvent mediated decomposition of tosylhydrazones: Highly selective synthesis of N-alkyl substituted hydrazones, dialkylidenehydrazines, and oximes
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Base and solvent mediated decomposition of tosylhydrazones was studied. It was found that reaction of tosylhydrazones in CH3NO2 in the presence of 1 equiv of K2CO3 in 90 °C gave N-alkylated products in 52-96% yield. However, when the same reaction was carried out in mixed solvent of CH3NO2 and dioxane in the presence of 3 equiv of NaOH at 110 °C, dialkylidenehydrazines were obtained in moderate to high yield. If the reaction was carried out in mixed solvent of CH3NO2 and DMSO in the presence of 10 equiv of NaOH at 110 °C, CH3NO2 can act as the precursor of hydroxylamine and corresponding oximes were formed in up to 92% yield.
- Sha, Qiang,Wei, Yunyang
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supporting information
p. 3829 - 3835
(2013/07/05)
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- Dissociation or cyclization: Options for a triad of radicals released from oxime carbamates
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A set of oxime carbamates having N-alkyl and N,N-dialkyl substituents were prepared via carbonyldiimidazole intermediates. It was shown by EPR spectroscopy that they underwent clean homolysis of their N-O bonds upon UV photolysis. During photolysis of acetophenone O-allylcarbamoyl oxime, the corresponding oxazolidin-2-onylmethyl radical was detected by EPR spectroscopy, providing the first evidence that N-monosubstituted carbamoyloxyl radicals can hold their structural integrity. N,N-Disubstituted carbamoyloxyl radicals dissociated rapidly at the lowest accessible temperatures. Above room temperature, both types of oxime carbamate acted as selective new precursors for aminyl and iminyl radicals. Rate parameters were measured for 5-exo cyclization of N-benzyl-N-pent-4-enylaminyl radicals; the rate constant was smaller than for C-centered and O-centered analogues. Oxime carbamates derived from the volatile diethylamine afforded aryliminyl radicals that proved convenient for phenanthridine preparations.
- McBurney, Roy T.,Walton, John C.
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supporting information
p. 7349 - 7354
(2013/06/27)
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- Synthesis of diarylmethanes via metal-free reductive cross-coupling of diarylborinic acids with tosyl hydrazones
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This paper describes a practical and efficient procedure that takes advantage of diarylborinic acids as a cost-effective alternative to arylboronic acids for synthesis of diarylmethanes through metal-free reductive cross-coupling with N-tosylhydrazones of aromatic aldehydes and ketones. The procedure tolerates hydroxyl, halide, amine, and allyl functionality, complementary to the transition-metal catalyzed cross-coupling techniques.
- Li, Xijing,Feng, Yuanyuan,Lin, Lin,Zou, Gang
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p. 10991 - 10995
(2013/02/22)
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- Copper-catalyzed N-N bond formation by homocoupling of ketoximes via n-o bond cleavage: Facile, mild, and efficient synthesis of azines
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A facile, mild, and efficient copper-catalyzed homocoupling of ketoximes involving N-O bond cleavage in the presence of sodium bisulfite (NaHSO has been developed. This reaction shows good functional group tolerance and affords a broad scope of azines in high yields.
- Zhao, Mi-Na,Liang, Hao,Ren, Zhi-Hui,Guan, Zheng-Hui
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scheme or table
p. 1501 - 1506
(2012/06/18)
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- Thermolysis and photolysis of N-benzoylhydrazone derivatives
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Two selected N-benzoylhydrazones were subjected to thermolysis by refluxing at 200 °C. Benzil, benzoic acid, biphenyl, benzanilide together with the corresponding ketones, nitriles, substituted methanes, and imines were isolated. Similar treatment of a third hydrazone at 250 °C afforded, in addition to the previous products, toluene, bibenzyl, stilbene, and 2-phenylindole. Photolysis of the same hydrazones in acetonitrile gave the previously reported products but in different ratios along with azine derivatives and substituted methanes. A free radical mechanism involving homolysis of the N-N and C-N bonds is suggested, substantiated by trapping of the phenyl radical with isoquinoline, to account for the formation of the identified products.
- Gaber, Abd El-Aal M.,Khairou, Khalid S.
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experimental part
p. 1021 - 1027
(2012/07/27)
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- Isolation and structural characterization of the elusive 1:1 adduct of hydrazine and carbon dioxide
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A solid hydrazine was isolated as a crystalline powder by reacting aqueous hydrazine with supercritical CO2. Its structure determined by single crystal X-ray diffraction shows a zwitterionic form of NH3 +NHCO2-. The solid hydrazine is remarkably stable but is as reactive as liquid hydrazine even in the absence of solvents.
- Lee, Byeongno,Kang, Seung Hee,Kang, Donghyeon,Lee, Kyu Hyung,Cho, Jaeheung,Nam, Wonwoo,Han, Oc Hee,Hur, Nam Hwi
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supporting information; experimental part
p. 11219 - 11221
(2011/12/05)
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- The electrochemical reduction of 1,4-dichloroazoethanes: Reductive elimination of chloride to form aryl azines
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A series of 1,4-dichloroazoethanes (1-X/Y, X and Y = 4-NO2, 4-CN, 4-CH3 or 4-H) were studied in N,N-dimethylformamide using cyclic voltammetry, constant potential sweep voltammetry (CPSW) and constant potential electrolysis. The voltammograms of 1-X/Y exhibit an irreversible two-electron wave corresponding to dissociative electron transfer (DET) reduction of the carbon-chlorine bond resulting in formation of the azines 2-X/Y in quantitative yield. Additional redox waves correspond to the reversible reduction of the azines to the 2-X/Y?- radical anion and 2-X/Y2-dianion consecutively, with the exception of 1-NO 2/NO2 where both NO2 groups are reduced simultaneously in a two-electron reversible wave. Thermodynamic and kinetic parameters were determined from CPSW: the standard reduction potentials (E o) vary between-0.7 and-1.3V versus SCE as a function of electron-withdrawing substituent; the heterogeneous rate constants (khet) are consistent with a slow heterogeneous electron transfer with values ranging from 10-3 to 10-5 cms-1; the transfer coefficients (α) for 1-NO2/NO2 and 1-NO2/H are greater than 0.5, indicative of a stepwise DET mechanism for the C-Cl bond cleavage while the remaining 1-X/Y compounds have α values between 0.35 and 0.5, and the intrinsic barriers are all significantly lower than predicted for a concerted DET, thereby also suggesting a stepwise DET mechanism.
- Sauro, Vittorio A.,Magri, David C.,Pitters, Jason L.,Workentin, Mark S.
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scheme or table
p. 5584 - 5591
(2010/09/06)
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- Synthesis of functionalized diaryl alkancs from azines
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Substituted diaryl alkanes arc synthesized from bcnzalazines and acctophenone/propiophenone azines via Friedel Craft's reaction with substituted mono- and poly-nuclear aromatic hydrocarbons. Diaryl methanes/ethanes and propanes are obtained by reaction with benzalazine, N,N'-bis (I-phenyl) azine and N, N'-bis (I-propyl) azine, respectively.
- Manih, Rudolf M.,Myrboh, Bekington
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experimental part
p. 146 - 151
(2009/12/01)
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- Oxadiazoline ligands for modulating the expression of exogenous genes via an ecdysone receptor complex
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The present invention relates to non-steroidal ligands for use in nuclear receptor-based inducible gene expression system, and a method to modulate exogenous gene expression in which an ecdysone receptor complex comprising: a DNA binding domain; a ligand binding domain; a transactivation domain; and a ligand is contacted with a DNA construct comprising: the exogenous gene and a response element; wherein the exogenous gene is under the control of the response element and binding of the DNA binding domain to the response element in the presence of the ligand results in activation or suppression of the gene.
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Page/Page column 29
(2008/06/13)
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- A convenient synthesis of azines under solvent-free conditions using microwave irradiation
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In an extremely fast method the reaction of hydrazine sulfate with a number of aldehydes and ketones, is accelerated by microwave irradiation under solvent free conditions in the presence of CH2CO2Na/CaCl2 to afford high yields of relevant azines.
- Khouzani-Loghmani, Hossein,Sadeghi, Majid M. M.,Safari, Javad,Abdorrezaie, Mohammad S.,Jafarpisheh, Masood
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- Oxidative Transformations of Aldazines and Ketazines with Organic Peroxyacids
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Oxidation of aromatic aldazines and ketazines with various peroxycarboxylic acids was investigated.It was found that one part of azine molecule 2 was converted into carbonyl compound 1 or related acid 3 while the second part was transformed into carboxylic ester 4 related to peroxyacid used as an oxidant.It was revealed that aromatic azines could be used as a source of diazaarylmethanes and mechanisms of reactions studied were postulated. aldazines, carboxylic esters, ketazines, oxidation, peroxycarboxylic acids
- Mlochowski, J.,Giurg, M.
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p. 2333 - 2342
(2007/10/02)
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- Azine synthesis via nitrogen-nitrogen bond formation
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Imine anions, generated by reaction of nitriles with organometallic reagents, are dimerized to form symmetrical azines through the use of CuI and t-butyl peroxybenzoate.
- Love,Tsai
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p. 3101 - 3108
(2007/10/02)
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- Formation and Reactivity of ?-Radical Cation Intermediates in the C-C Coupling Reaction of Phenyldiazomethanes by One-Electron Oxidation
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One-electron oxidation of phenyldiazomethanes afforded cis-stilbene predominantly.The reaction was independent of the oxidation methods, e.g., electrolysis, copper(II), triarylaminium salts, or photosensitized one-electron oxidtions.The C-C coupling reaction was retarded by introducing α-substituents on phenyldiazomethanes.The ESR spectra of diazoalkane radical cations could be obtained during the electrolysis at low temperature and the resulting spectra revealed their unique electronic structure as ?-radicals for most cases.When a bulky tert-butyl group was substituted, the corresponding ?-radical cation was observed, but the C-C coupling reaction did not occur.The novel HOMO-LUMO switching by one-electron removal from the HOMO ?-orbital of diazomethane is explained by the interaction of phenyl group with the C-N-N ?-radical moiety.The C-C coupling reaction proceeds via facile cycloaddition between the diazomethane and ?-radical cation, and the preferential formation of cis-olefins is based on the secondary orbital interaction between the two phenyl groups.The structure and the stability of radical cation intermediates are rationalized on the basis of ab initio calculations.
- Ishiguro, Katsuya,Ikeda, Masatoshi,Sawaki, Yasuhiko
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p. 3057 - 3066
(2007/10/02)
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- Copper-ammonia mediated oxidation of carbonyl compounds
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Copper(II) in aqueous NH4OH, in most cases in conjunction with O2 or K2S2O8 as auxiliary oxidant, induces oxidative cleavage of ketones to nitriles when there is a good carbon electrofuge; for unactivated ketones, the main reaction observed is oxidative coupling of ketimines to give azines. If R′ = poor electrofuge, oxidative coupling to RR′ C=N-N=CRR′ can occur.
- Arora, Pramod K.,Sayre, Lawrence M.
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p. 1007 - 1010
(2007/10/02)
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- DIAZIRINES IN CARBENOID REACTIONS CATALYZED BY RHODIUM(II) CARBOXYLATES
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Diazo compounds formed by thermal or photolytic rearrangement of 3-alkyl-3-phenyl-diazirines in the presence of catalytic amounts of rhodium(II) perfluorobutyrate are effectively directed to metal carbenoid products with minimal competition from processes which are dominant when the diazo compound is used directly or when the diazirine is decomposed in the absence of the catalyst.
- Doyle, Michael P.,High, Kenneth G.,Oon, Su-Min,Osborn, Antonio K.
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p. 3049 - 3052
(2007/10/02)
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- Stereoselective Azine Formation in the Decomposition of Phenyldiazomethanes
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The bimolecular dimerization of phenyldiazomethane (1) and 1-diazo-1-phenylethane (2) to form the corresponding azines (3 and 4) is stereoselective for the E,Z isomer (>95:5 E,Z:E,E).The E,Z isomer can be isolated from the reaction of 2, and it can be observed but not isolated from the reaction of 1.Both (E,Z)-3 and -4 revert thermally to the more stable E,E isomer.The kinetic parameters of this process were determined for (E,Z)-4: Ea = 22.3 kcal/mol, log A = 11.2.The stereoselectivity is accounted for within the context of the accepted mechanism for azine formation via diazo compound dimerization.
- Abelt, Christopher J.,Pleier, Jennifer M.
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p. 1795 - 1799
(2007/10/02)
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- COMPLEXES OF CYCLOMALTOHEPTAOSE WITH AROMATIC DIAZO COMPOUNDS: FORMATION AND REACTIONS
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Pyrolysis of the relatively stable, solid complexes of cyclomaltoheptaose (β-cyclodextrin) with phenyldiazomethane, 1-diazo-1-phenylethane, and diazo(diphenyl)methane results in degradation of the labile guests.The host matrix exerts "reaction-vessel" and "shape-selectivity" effects upon the reaction pathways of the guests and derivatives.The carbene insertion reaction with the β-cyclodextrin hydroxyl groups is regioselective.
- Abelt, Christopher J.,Lokey, Jonathan S.,Smith, Shelley H.
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p. 119 - 130
(2007/10/02)
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- Products from Reactions of Methyl (E)-2-Cyano-3-(p-substituted-phenyl)acrylates with 1-Phenyldiazoethane and Cycloreversion of Secondary Pyrazolines
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In dichloromethane, the reaction of methyl (E)-2-cyano-3-(p-substituted-phenyl)acrylates (2) with 1-phenyldiazoethane (1), prepared from 2 molar equiv of acetophenone hydrazone, produced methyl 2-cyano-4-phenyl-4-(p-substituted-phenyl)-2-pentenoates (3), 1-cyano-1-(methoxycarbonyl)-2-methyl-2-phenyl-3-(p-substituted-phenyl)cyclopropanes (4), and 4-cyano-4-(methoxycarbonyl)-3-methyl-3-phenyl-5-(1-phenyl-1-(p-substituted-phenyl)ethyl)-1-pyrazolines (5).Compounds 5 were found to be derived from compounds 3 and 1.Compounds 5 were different from the primary pyrazolines derived from compounds 1 and 2, both in mode of formation and properties.Compounds 5, when decomposed thermally or photochemically, produced the initial olefins 3.This decomposition is an example of "true" cycloreversion.
- Nagai, Wakatu,Hirata, Yumiko
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p. 635 - 640
(2007/10/02)
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- β-Cyclodextrin as a Molecular Reaction Vessel: Reactions of Included Phenylmethyldiazirine
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Phenylmethyldiazirine forms a stable, solid complex with β-cyclodextrin.The diazirine was decomposed by pyrolysis or irradiation of the complex, and the reaction products were analyzed.The major volatile products consist of the isomeric 1,2-diphenyl-1-methylcyclopropanes.Under photolytic conditions a significant amount of styrene also is formed.The selectivity for trans isomer formation is 10 times greater from the CD complex than from the neat state.Carbene insertion products with β-cyclodextrin are formed under both reaction conditions.The product distributions are explained by cage and shape-selective effects exerted by β-cyclodextrin.
- Abelt, Christopher J.,Pleier, Jennifer M.
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p. 2159 - 2162
(2007/10/02)
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- Structure and reactivity in highly halogenated ketazines
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The azines of acetophenone and its mono- and di-chlorinated derivatives show a bathochronic shift in the yellow region, but the azine of trichloroacetophenone is colorless.Similar trends are observed in the brominated analogs and in the chlorinated propiophenone azines.The colorless tetrachloropropiophenone azine (13) is shown by X-ray analysis to be nonplanar at the azine atoms (N-N torsion angle, 126.7 deg).Hexachloroacetophenone azine (9) undergoes displacement of all its chlorines with NaOMe to give the hexamethoxy compound 16, also colorless.With acid, 16 gives the yellow planar (X-ray) ketazine diester 20.These reactions appear to be general for the trichloromethyl group in azines, but not for the α,α-dichloroalkyl group, attempts at the sequence 13 to 28 proving unsuccessful.
- Lai, Ellen C. K.,MacKay, Donald,Taylor, Nicholas J.,Watson, Kenneth N.
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p. 2839 - 2848
(2007/10/02)
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- Diazomethane Radical Cations as a Dipolarophile in the Dimeric Olefin Formation from Diazo-compounds
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A novel cycloaddition mechanism involving diazomethane radical cations is proposed for the dimeric olefin formation by the one-electron oxidation of the diazo-compounds.The preference of cis-stilbene formation from phenyldiazomethane is understood by a secondary orbital interaction of phenyl groups on the cycloaddition step.
- Ishiguro, Katsuya,Sawaki, Yasuhiko,Iwamura, Hiizu
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p. 1853 - 1856
(2007/10/02)
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- RHODIUM ION CATALYZED DECOMPOSITION OF ARYLDIAZOALKANES
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Aryldiazomethanes are converted by rhodium(II)acetate and iodorhodium(III) tetraphenylporphyrin to cis- rather than trans-1,2-diarylethylenes.Secondary aryldiazoalkanes react with rhodium(II) acetate to give azines.
- Shankar, B.K. Ravi,Shechter, Harold
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p. 2277 - 2280
(2007/10/02)
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- Unsaturated Compounds containing Nitrogen. Part 4. Further Reactions of 1-Chloro-2,3-diazabutadienes with S-Nucleophiles
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1-Chloro-1,4-diaryl-2,3-diazabutadienes (Ar1CCl=NN=CHAr2), prepared by the reaction of thionyl chloride with aroylhydrazones (Ar1CONHN=CHAr2), react with thiosemicarbazide or thiocarbohydrazide to give 2-arylidenehydrazino-5-aryl-1,3,4-thiadiazoles, and with potassium thiocyanate to give 1-thiocyanato-1,4-diaryl-2,3-diazabutadienes which isomerize thermally to arylideneamino-5-aryl-1,3,4-thiadiazoles. 1-Chloro-1,4-diphenyl-2,3-diazabutadiene reacts with potassium ethylxanthate to give a 1-ethylxanthyl-2,3-diazabutadiene which on pyrolysis yields 2,5-diphenyl-1,3,4-thiadiazole.
- Flowers, William T.,Robinson, John F.,Taylor, David R.,Tipping, Anthony E.
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p. 349 - 355
(2007/10/02)
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- The Photolysis of p-Tosylhydrazones of Aryl and α,β-Unsaturated Carbonyl Compounds
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The ultraviolet irradiation of p-tosylhydrazones of aryl and α,β-unsaturated carbonyl compounds yields azines and sulphones and exhibits a strong solvent effect.Styryl substrates afford α,β-unsaturated sulphones, the shift of the olefinic double bond probably arising through an intermediate azoderivative.The p-tosylhydrazone of benzylideneacetone is to a great extent transformed to the cis isomer.
- Bellesia, Franco,Grandi, Romano,Pagnoni, Ugo M.,Trave, Roberto
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p. 1301 - 1309
(2007/10/02)
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