- Deconjugative α-Alkylation of Cyclohexenecarboxaldehydes: An Access to Diverse Terpenoids
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A general and efficient method for the deconjugative α-alkylation of α,β-unsaturated aldehydes promoted by a synergistic effect between tBuOK and NaH, which considerably increases the reaction rate under mild conditions, is reported. The β,γ-unsaturated aldehyde, resulting from the α-alkylation, is transformed in high yield into the corresponding allyl acetate via a lead(IV) acetate-mediated oxidative fragmentation. This strategy could be used for the construction of the carbon skeleton of a wide variety of alkyl or arylterpenoids.
- Chahboun, Rachid,Botubol-Ares, José Manuel,Durán-Pe?a, María Jesús,Jiménez, Fermín,Alvarez-Manzaneda, Ramón,Alvarez-Manzaneda, Enrique
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p. 8742 - 8754
(2021/07/19)
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- [1,3]-Claisen rearrangement via removable functional group mediated radical stabilization
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A thermal O-to-C [1,3]-rearrangement of α-hydroxy acid derived enol ethers was achieved under mild conditions. The 2-aminothiophenol protection of carboxylic acids facilitates formation of the [1,3] precursor and its thermal rearrangement via stabilization of a radical intermediate. Experimental and theoretical evidence for dissociative radical pair formation, its captodative stability via aminothiophenol, and a unique solvent effect are presented. The aminothiophenol was deprotected from rearrangement products as well as after derivatization to useful synthons.
- Alam, Md Nirshad,Dash, Soumya Ranjan,Mukherjee, Anirban,Pandole, Satish,Marelli, Udaya Kiran,Vanka, Kumar,Maity, Pradip
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supporting information
p. 890 - 895
(2021/02/01)
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- Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
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The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
- Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
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supporting information
p. 4197 - 4204
(2018/09/25)
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- Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
- Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
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supporting information
p. 4933 - 4939
(2018/12/14)
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- Substituent Dependent Optical Properties of p-phenyl Substituted ethenyl-E-thiophenes
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Various electron donor and acceptor substituted (NO2, CN, Cl, H, OCH3, NH2) p-phenyl ethenyl-E- thiophenes (1–6) were synthesized and substituent dependent optical properties (dipole moment, transition dipole moment, oscillator strength, optical band gap, hyperpolarizability) were studied using Solvatochromism and Density functional theory. It is shown that thiophene acts as a weak electron donor in presence of an electron withdrawing p-phenyl substituent (NO2, CN, Cl), whereas thiophene acts as a weak electron acceptor in presence of an electron donating p-phenyl substituent (OCH3, NH2). In comparison to ethenyl thiophene 4, the HOMO-LUMO energy band gap is decreased upon increasing the electron donating or electron withdrawing capacity of p-phenyl substituent. From the excited state dipole moment calculation, it is shown that the excited state is highly dipolar for nitro and amino compounds 1 and 6, whereas compounds 2–5 show a non-polar excited state. As compared to the ethenyl thiophene 4, the first hyperpolarizability (β) increases upon substitution either with a strong electron withdrawing or strong electron donating p-phenyl substituent. A large β value is found for p-nitro phenyl ethenyl-E-thiophene and p-amino phenyl ethenyl-E- thiophene. Overall, these studies provide useful information in understanding the optical properties of phenyl and heterocyclic based ethenyl systems.
- Kumar, Naresh,Paramasivam, Mahalingavelar,Kumar, Jagdeep,Gusain, Anamika,Hota, Prasanta Kumar
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p. 1207 - 1216
(2018/09/10)
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- One-pot synthesis of α,β-epoxy ketones through domino reaction between alkenes and aldehydes catalyzed by proline based chiral organocatalysts
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Proline based metal free organocatalysts were developed by using a new approach for the synthesis of epoxide derivatives through a domino reaction. This domino reaction (oxidative coupling) allows a direct access to epoxides from various alkenes and aldehydes through C-H functionalization and C-C/C-O bond formation. The catalytic efficiencies of the newly synthesized organocatalysts were also determined by domino reaction in the presence of various functional groups containing aldehyde and alkene derivatives with very good yields (up to 95%) and ee's (up to 99%).
- Ashokkumar, Veeramanoharan,Siva, Ayyanar
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p. 2551 - 2561
(2017/04/03)
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- Benzylsulfanyl benzo-heterocycle amides and hydrazones as new agents against drug-susceptible and resistant: Mycobacterium tuberculosis
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A series of benzylsulfanyl benzo-heterocycle amides and hydrazones were synthesized and evaluated for anti-tubercular activities. The isonicotinyl hydrazone derivatives 12d, 12e and 12f exhibited good anti-tubercular activity against Mycobacterium tuberculosis H37Rv (ATCC #27294) with MIC values of 0.23, 0.24 and 0.24 μM, respectively, and were also active against SDR-TB, MDR-TB and XDR-TB. More importantly, compound 12e also showed low cytotoxicity and good metabolic stability, and could significantly reduce the mycobacterial burden in a mouse model infected with autoluminescent H37Ra strain, which may serve as a lead compound for further development.
- Lu, Xiaoyun,Hu, Xianglong,Liu, Zhiyong,Zhang, Tianyu,Wang, Ruibing,Wan, Baojie,Franzblau, Scott G.,You, Qidong
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supporting information
p. 1303 - 1306
(2017/07/07)
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- Palladium-catalyzed silylation reaction between benzylic halides and silylboronate
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An efficient Pd-catalyzed silylation reaction of benzylic halides with silylboronate is reported. In this reaction, primary and secondary benzylic halides could react well with silylboronates to afford benzylic silanes. This reaction accommodates a broad substrate scope and proceeds smoothly under very mild reaction conditions. The corresponding products could be obtained in moderate to high yields and with stereospecificity.
- Huang, Zhi-Dao,Ding, Ran,Wang, Peng,Xu, Yun-He,Loh, Teck-Peng
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supporting information
p. 5609 - 5612
(2016/05/09)
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- An efficient and selective method for the iodination and bromination of alcohols under mild conditions
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A straightforward and effective procedure for the conversion of a variety of alcohols into the corresponding alkyl iodides and bromides is described using KX/P2O5 (X = I, Br). The reactions were easily carried out in acetonitrile under mild conditions. Using this method, the selective conversion of benzylic alcohols in the presence of aliphatic alcohols was achieved.
- Khazdooz, Leila,Zarei, Amin,Aghaei, Hamidreza,Azizi, Ghobad,Gheisari, Mohammad Mehdi
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p. 168 - 171
(2015/12/30)
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- One-Step Synthesis of Substituted Benzofurans from ortho- Alkenylphenols via Palladium-Catalyzed C=H Functionalization
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A dehydrogenative oxygenation of C(sp2)=H bonds with intramolecular phenolic hydroxy groups has been developed, which provides a straightforward and concise access to structurally diversely benzofurans from ortho-alkenylphenols. The reaction is catalyzed by palladium on carbon (Pd/C) without any oxidants and sacrificing hydrogen acceptors.
- Yang, Dejun,Zhu, Yifei,Yang, Na,Jiang, Qiangqiang,Liu, Renhua
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supporting information
p. 1731 - 1735
(2016/06/09)
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- P(NMe2)3-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
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A commercial phosphorus-based reagent (P(NMe2)3) mediates umpolung alkylation of methyl aroylformates with benzylic and allylic bromides, leading to either Barbier-type addition or ylide-free olefination products upon workup. The reaction sequence is initiated by a two-electron redox addition of the tricoordinate phosphorus reagent with an α-keto ester compound (Kukhtin-Ramirez addition). A mechanistic rationale is offered for the chemoselectivity upon which the success of this nonmetal mediated C-C bond forming strategy is based.
- Wang, Sunewang Rixin,Radosevich, Alexander T.
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supporting information
p. 3810 - 3813
(2015/08/18)
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- A scalable procedure for light-induced benzylic brominations in continuous flow
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A continuous-flow protocol for the bromination of benzylic compounds with N-bromosuccinimide (NBS) is presented. The radical reactions were activated with a readily available household compact fluorescent lamp (CFL) using a simple flow reactor design based on transparent fluorinated ethylene polymer (FEP) tubing. All of the reactions were carried out using acetonitrile as the solvent, thus avoiding hazardous chlorinated solvents such as CCl4. For each substrate, only 1.05 equiv of NBS was necessary to fully transform the benzylic starting material into the corresponding bromide. The general character of the procedure was demonstrated by brominating a diverse set of 19 substrates containing different functional groups. Good to excellent isolated yields were obtained in all cases. The novel flow protocol can be readily scaled to multigram quantities by operating the reactor for longer time periods (throughput 30 mmol h-1), which is not easily possible in batch photochemical reactors. The bromination protocol can also be performed with equal efficiency in a larger flow reactor utilizing a more powerful lamp. For the bromination of phenylacetone as a model, a productivity of 180 mmol h -1 for the desired bromide was achieved.
- Cantillo, David,De Frutos, Oscar,Rincon, Juan A.,Mateos, Carlos,Oliver Kappe
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supporting information
p. 223 - 229
(2014/01/17)
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- Synthesis and evaluation of the antiparasitic activity of bis-(arylmethylidene) cycloalkanones
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A series of bis-(arylmethylidene)-cycloalkanones was synthesized by cross-aldol condensation. The activity of the compounds was evaluated against amastigotes forms of Trypanosoma cruzi and promastigotes forms of Leishmania amazonensis. The cytotoxicity of the active compounds on uninfected fibroblasts or macrophages was established in vitro to evaluate the selectivity of their antiparasitic effects. Six compounds displayed trypanocidal activity against amastigotes intracellular forms of T. cruzi with IC50 values ranging from 7.0 to 249 μM. Besides these six compounds, eight other molecules exhibited significant leishmanicidal activity (IC50 values ranging from 0.6 to 110.4 μM). Two compounds can be considered as promising antiparasitic lead molecules because they showed IC50 values in the low-micromolar range (≤1.2 μM) with an adequate SI (≥19.9). To understand the mechanism of action of these compounds, two possible molecular targets were investigated: trypanothione reductase (TR) and cruzain.
- Braga, Saulo F.P.,Alves, érika V.P.,Ferreira, Rafaela S.,Fradico, Jordana R.B.,Lage, Paula S.,Duarte, Mariana C.,Ribeiro, Tatiana G.,Júnior, Policarpo A.S.,Romanha, Alvaro J.,Tonini, Maiko L.,Steindel, Mário,Coelho, Eduardo F.,De Oliveira, Renata B.
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p. 282 - 289
(2014/01/06)
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- One-pot transformation of methylarenes into aromatic aldehydes under metal-free conditions
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On the basis of studies of the transformation of benzylic bromides into the corresponding aromatic aldehydes by treatment with N-methylmorpholine N-oxide, various methylarenes were treated either with DBDMH in the presence of AIBN in acetonitrile at reflux (Method A) or with NBS in CCl4 under irradiation with a tungsten lamp at 30 °C (Method B), followed by treatment with N-methylmorpholine N-oxide to provide aromatic aldehydes in good yields. These methods could be adopted in one-pot transformations of methylarenes into aromatic aldehydes under conditions free of less toxic reagents and transition metals. Copyright
- Tabata, Masayuki,Moriyama, Katsuhiko,Togo, Hideo
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p. 3402 - 3410
(2014/06/09)
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- A base-induced ring-opening process of 2-substituted-1,3,4-oxadiazoles for the generation of nitriles at room temperature
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A novel base-catalysed 1,3,4-oxadiazole fragmentation for the synthesis of nitriles at room temperature has been developed. This reaction is performed under transition-metal-free conditions, and provides a new ring cleavage reaction of 1,3,4-oxadiazoles in organic synthesis.
- Lu, Guo-Ping,Lin, Ya-Mei
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p. 371 - 374
(2014/07/08)
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- Highly enantioselective asymmetric Michael addition reactions with new chiral multisite phase-transfer catalysts
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Highly enantioselective Michael addition reactions of diethyl malonate to various chalcones have been achieved under mild chiral multisite phase-transfer reaction conditions by the successful utilization of 2,4,6- (triscinchoniummethyl)phenyl-1,3,5-triazines as new chiral quaternary ammonium catalysts. This simple asymmetric Michael addition process was found to be quite effective and to obtain Michael adducts with very good yields and enantiomeric excesses. Georg Thieme Verlag Stuttgart New York.
- Jayaraman, Sivamani,Kumaraguru, Duraimurugan,Arockiam, Jesin Beneto,Paulpandian, Subha,Rajendiran, Balasaravanan,Siva, Ayyanar
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supporting information
p. 1685 - 1691
(2014/08/05)
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- Direct oxidative conversion of methylarenes into aromatic nitriles
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A variety of methylarenes were successfully converted into the corresponding aromatic nitriles in good to moderate yields by the treatment with NBS or DBDMH in the presence of a catalytic amount of AIBN or BPO, followed by the reaction with molecular iodine in aq NH3 in a one-pot procedure. The present reaction is a useful and practical transition-metal-free method for the preparation of aromatic nitriles from methylarenes.
- Tsuchiya, Daisuke,Kawagoe, Yuhsuke,Moriyama, Katsuhiko,Togo, Hideo
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supporting information
p. 4194 - 4197
(2013/09/12)
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- A facile total synthesis for large-scale production of imatinib base
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An efficient, economic process has been developed for the production of imatinib with 99.99% purity and 50% overall yield from four steps. Formation and control of all possible impurities is described. The synthesis comprises the condensation of N-(5-amino-2-methylphenyl)-4-(3-pyridinyl)-2-pyrimidineamine with 4-(4-methylpiperazinomethyl)benzoyl chloride in isopropyl alcohol solvent in the presence of potassium carbonate to yield imatinib base.
- Kompella, Amala,Adibhatla, Bhujanga Rao Kalisatya,Muddasani, Pulla Reddy,Rachakonda, Sreenivas,Gampa, Venugopala Krishna,Dubey, Pramod Kumar
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p. 1794 - 1804
(2013/01/15)
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- Photoresponsive soft materials: Synthesis and photophysical studies of a stilbene-based diblock copolymer
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An amphiphilic diblock copolymer composed of a photoresponsive dialkoxycyanostilbene polymethacrylate and poly(ethylene oxide) (PDACS-b-PEO) was synthesized and its photophysical and aggregation properties were investigated. The amphiphilic nature of the polymer caused it to self-assemble in water, and dynamic light scattering studies indicated formation of spherical aggregates with an average size of 160 nm. Atomic force microscopy images of dried films cast from solutions containing the polymer aggregates revealed supramolecular aggregates with a spherical morphology. Photoisomerization of the stilbene chromophore in PDACS-b-PEO on UV irradiation resulted in the destruction of the self-assembled superstructures which could be attributed both to change in shape of the chromophore from the linear trans isomer to the bent cis isomer which would hinder self-aggregation of the molecules and the higher dipole moment of the cis isomer leading to a reduction of the hydrophobic nature of the stilbene containing block of PDACS-b-PEO. It was observed that hydrophobic dyes such as curcumin could be encapsulated within the hydrophobic interior of the spherical micellar aggregates from which the encapsulated dye could be released on UV irradiation.
- Menon, Sajith,Thekkayil, Remyamol,Varghese, Shinto,Das, Suresh
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experimental part
p. 5063 - 5073
(2012/06/01)
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- Synthesis and biological evaluation of 2-phenylthiazole-4-carboxamide derivatives as anticancer agents
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A series of substituted 2-phenylthiazole-4-carboxamide derivatives were synthesized as potential cytotoxic agents and evaluated against three human cancer cell lines including T47D (Breast cancer), Caco-2 (Colorectal cancer) and HT-29 (Colon cancer). The SAR of the arylacetamido pendent connected to the para-position of 2-phenylthiazole were explored. It was found that substitution at the 4-position by a methoxy group led to improvement of activity against Caco-2 cells while 2-methoxy substituent could maintain the high activity against HT-29 and T47D cell lines. Also, 3-fluoro analog showed good cytotoxic activity profile against all cell lines with IC50 values less than 10 μg/mL.
- Aliabadi, Alireza,Shamsa, Fazel,Ostad, Seyed Nasser,Emami, Saeed,Shafiee, Abbas,Davoodi, Jamshid,Foroumadi, Alireza
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experimental part
p. 5384 - 5389
(2011/01/04)
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- Benzylic bromination of toluene derivatives with boron tribromide
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A facile method for the benzylic bromination of toluene derivatives was developed. Various substituted toluenes were brominated with boron tribromide as bromine source in carbon tetrachloride at room temperature, affording their corresponding benzyl bromides in good yields.
- Chen, Hongbiao,Shen, Litao,Lin, Yuanbin
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experimental part
p. 998 - 1003
(2010/05/18)
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- Targeting Alzheimer's disease: Novel indanone hybrids bearing a pharmacophoric fragment of AP2238
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We report on a series of hybrid compounds structurally derived from donepezil and AP2238. This study was aimed at improving the activities of the reference compounds, donepezil and AP2238, and at broadening the range of activities of new derivatives as, due to the multifactorial nature of AD, molecules that modulate the activity of a single protein target are unable to significantly modify the progression of the disease. In particular, the indanone core from donepezil was linked to the phenyl-N-methylbenzylamino moiety from AP2238, through a double bond that was kept to evaluate the role of a lower flexibility in the biological activities. Moreover, SAR studies were performed to evaluate the role of different substituents in position 5 or 6 of the indanone ring in the interaction with the PAS, introducing also alkyl chains of different lengths carrying different amines at one end. Derivatives 21 and 22 proved to be the most active within the series and their potencies against AChE were in the same order of magnitude of the reference compounds. Compounds 15, 21-22, with a 5-carbon alkyl chain bearing an amino moiety at one end, better contacting the PAS, remarkably improved the inhibition of AChE-induced Aβ aggregation with respect to the reference compounds. They also showed activity against self-aggregation of Aβ42 peptide, the most amyloidogenic form of amyloid produced in AD brains, while the reference compounds resulted completely ineffective.
- Rizzo, Stefano,Bartolini, Manuela,Ceccarini, Luisa,Piazzi, Lorna,Gobbi, Silvia,Cavalli, Andrea,Recanatini, Maurizio,Andrisano, Vincenza,Rampa, Angela
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experimental part
p. 1749 - 1760
(2010/05/17)
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- Hierarchical self-assembly of heteronuclear co-ordination networks
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Two ligands L1 and L2 have been prepared which contain a chelating pyrazolyl-pyridine group with a pendant aromatic nitrile (in L1, a benzonitrile; in L2, a naphthonitrile). These ligands react with Ag(i) salts to give a range of infinite coordination networks or dimeric 'boxes' in which the pyrazolyl-pyridine chelates and the aromatic nitrile groups both participate in coordination to Ag(i) ions. In contrast, L1 and L2 form simple mononuclear tris-chelates [ML 3]2+ with first-row transition metal dications (M = Co, Ni, Zn) in which the aromatic nitrile groups are pendant such that the complexes can be used as 'complex ligands'. The crystal structures of [M(L 2)3](BF4)2 are based on solely the mer tris-chelate geometry although in solution 1H NMR spectroscopy reveals a mixture of both fac and mer isomers of the tris-chelates. Reaction of these with Ag(i) ions allows the interaction of the pendant nitrile groups with Ag(i) ions to generate coordination networks based on [ML3] 2+ cations being crosslinked by Ag(i) ions. In these networks the [ML3]2+ cations have solely the fac geometry and lie on threefold rotation axes with all three pendant nitrile groups coordinated to Ag(i) ions which are three-coordinate. {[AgM(L2)3][BF 4]3}∞ (M = Co, Ni) consist of two interpenetrated (10,3)a nets which have opposite chirality at the [M(L 2)3]2+ centres but are not strictly enantiomorphic as the two nets are not crystallographically equivalent. {[AgNi(L1)3](BF4)3} ∞ in contrast contains two-dimensional sheets which have a (6,3) net structure of hexagonal rings of alternative Ni(ii) and Ag(i) centres; although not interpenetrating, two such adjacent (and enantiomorphic) sheets interact with each other via numerous CH...π interactions between aromatic ligands. Formation of these structures shows that the differential reactivity of the two binding sites in L1 and L2 (pyrazolyl-pyridine, and nitrile) can be used to generate mixed-metal coordination networks in a hierarchical, stepwise manner.
- Fenton, Hazel,Tidmarsh, Ian S.,Ward, Michael D.
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body text
p. 3805 - 3815
(2010/06/17)
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- Environmentally-friendly Wohl-Ziegler bromination: Ionic-liquid reaction and solvent-free reaction
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Environmentally-friendly Wohl-Ziegler bromination of benzylic methyl groups was successfully camed out in ionic-liquid and solvent-free systems, to produce the corresponding benzylic bromides in good to moderate yields.
- Togo, Hideo,Hirai, Takeshi
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p. 702 - 704
(2007/10/03)
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- Noncovalent tripeptidic thrombin inhibitors incorporating amidrazone, amine and amidine functions at P1
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A series of noncovalent tripeptidic thrombin inhibitors incorporating amidrazone, amine and amidine functions at P1 was investigated. While the amidrazone and the amine series displayed limited oral absorption, the amidine series demonstrated generally good oral absorption and strong antithrombotic activity; the single-digit picomolar Ki achieved from this series is among the best yet reported. The present work highlights the benzamidine compound 11f (LB30812) that exhibits excellent overall profiles of potency, oral absorption and antithrombotic efficacy.
- Lee, Koo,Jung, Won-Hyuk,Park, Cheol Won,Park, Hee Dong,Lee, Sun Hwa,Kwon, O Hwan
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p. 1017 - 1022
(2007/10/03)
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- Anthranilic acid derivatives as inhibitors of the cGMP-phosphodiesterase
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Compounds of formula (I) STR1where R 1 is hydrogen; R 2 is nitro, cyano or halo(lower)alkyl; R 3 is phenyl substituted with one or more substituents selected from halogen, cyano and lower alkoxy; A is a lower alkylene group; R 4 is a group CR 6 R 7 R 8 wherein R 6 and R 7 form, together with the carbon atom to which they are attached a cycloalkyl group optionally substituted with hydroxy, lower alkoxy or a lower alkanoylamino; and R 8 is hydrogen; its prodrug and a salt thereof.
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- An efficient method for the preparation of benzylic bromides
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Substituted benzylic compounds are brominated with an excess of N-bromosuccinimide (NBS) in CCl4 to the corresponding polybrominated mixtures which are then debrominated with diethyl phosphite and N,N-diisopropylethylamine to afford the desired monobromides in satisfactory yields and high purity.
- Liu,Chen,Deng,Tu
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p. 2078 - 2080
(2007/10/03)
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- Process for producing cyanobenzyl compounds
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An industrially advantageous process for producing cyanobenzyl compounds under mild conditions from relatively easily available cyanobenzylamine having a cyano group on the benzene ring or a compound thereof which is ring-substituted with a chlorine atom, a fluorine atom, etc. The process for producing a cyanobenzyl compound includes transforming an aminomethyl group of a cyanobenzylamine compound into a hydroxymethyl group, a halogenomethyl group, or an acyloxymethyl group without causing damage to a cyano group on the benzene ring. The transformation may be carried out by use of nitrosonium ions.
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- Synthesis and electronic spectra of substituted oligo(phenylenevinylene)s
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A series of substituted oligo(p-phenylenevinylene)s (OPVs) with five benzene rings was prepared via PO-activated olefinations and Knoevenagel condensations. The central ring is substituted with two octyloxy groups to ensure good solubility of the OPVs and the lateral styrene units carry further substituents, with either electron-accepting or donating character and also combinations thereof. The spectral features of these OPVs are dominated by the basic chromophore; further auxochrome groups on the lateral rings (meta and para positions) shift the absorption and emission spectra only slightly to longer wavelengths. Significant bathochromic shifts (absorption ca 20 nm, emission ca 40 nm) are observed for OPVs with cyano groups on the terminal vinylene segments. The absorption spectra are independent from the concentration and solvatochromism is very small. The OPVs are photochemically stable to near-UV irradiation (366 nm) in neutral solution, whereas mid-UV irradiation (254 nm) causes decomposition of the chromophore. The presence of traces of acids or amines leads to different photochemical pathways. Copyright
- Detert, Heiner,Sugiono, Erli
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p. 587 - 590
(2007/10/03)
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- Reductive bromination of aromatic aldehydes using alkylboron dibromides
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The reductive bromination of aromatic aldehydes with isopinocampheyl boron dibromide in hexane at room temperature produces the corresponding benzyl bromides in excellent yields. (C) 2000 Elsevier Science Ltd.
- Kabalka, George W.,Wu, Zhongzhi,Ju, Yuhong
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p. 5161 - 5164
(2007/10/03)
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- Fluorobenzamidrazone thrombin inhibitors: Influence of fluorine on enhancing oral absorption
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LB30057 (1) is a selective and efficacious oral thrombin inhibitor. Fluorine-substitution on the phenylene ring of the benzamidrazone portion in both compound 1 and its derivatives gave, in many cases, enhanced oral absorption in rats while maintaining the intrinsic potency and selectivity. Compound 2 demonstrated a 3-fold increase in absorption.
- Lee, Koo,Jung, Won-Hyuk,Sang, Yeul Hwang,Lee, Sung-Hack
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p. 2483 - 2486
(2007/10/03)
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- Catalytic processes of oxidation by hydrogen peroxide in the presence of Br2 or HBr. Mechanism and synthetic applications
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The mechanism and the synthetic applications for the oxidation of alcohols, ethers, and aldehydes by H2O2 catalyzed by Bf2 or Br- in a liquid two-phase system (aqueous and organic) are reported. Aliphatic and benzylic primary alcohols and ethers show an opposite behavior, which has been rationalized on the ground of the different electronic configurations of the intermediate alkyl (π-type) and acyl (σ-type) radicals and their influence on enthalpic and polar effects. A two-phase system is particularly useful also for an efficient benzylic bromination by Br2 or Br-; the substitution of the benzyl bromide by OH, OR, and OCOR regenerates Br-, which can be recycled. The evaluation of the relative reactivities of the involved substrates and intermediates has allowed to develop a variety of simple, facile, convenient, and selective syntheses of alcohols, aldehydes, ketones, esters, and benzyl bromides, which fulfill the conditions for practical applications.
- Amati, Alessandro,Dosualdo, Gabriele,Zhao, Lihua,Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Bjorsvik, Hans-Rene
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p. 261 - 269
(2013/09/08)
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- Polyporphyrin thin films from the interfacial polymerization of mercaptoporphyrins
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Free-standing ultrathin films of aporphyrin homopolymer have been synthesized by interfacial polymerization of a mercaptoporphyrin. Coupling of 5,10,15,20-tetrakis(α-mercapto-p-tolyl)porphyrin at the water/ chloroform interface by copper acetate yields continuous, flexible films after drying with supercritical CO2. These films are amorphous and retain many characteristics of the monomeric porphyrin, such as the property that they may be metalated. Spectroscopic evidence suggests efficient cross-linking of thiols through disulfide coupling occurs in these polyporphyrins to form a network. Polymerization is accompanied by the introduction of carbonyl functionality, probably the transformation of residual thiols to thioacetate by metal-mediated reaction with excess acetate ion. As an example of the catalytic properties of these polymers, they are shown to promote photooxidation of thietane to the corresponding sulfoxide by sensitizing singlet oxygen production.
- Wen, Liqin,Li, Ming,Schlenoff, Joseph B.
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p. 7726 - 7733
(2007/10/03)
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- Triazolylated teritiary amine compound or salt thereof
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A triazolylated tertiary amine compound represented by general formula (I) or a salt thereof, having an aromatase inhibitory activity and being useful for preventing and treating breast cancer, mastopathy, endometriosis, prostatomergaly, etc., wherein A represents a single bond, lower alkylene or carbonyl; B represents lower alkyl, aryl, a 5- or 6-membered heterocyclic group, or a bicyclic fused heterocyclic group; D represents aryl, a 5- or 6-membered heterocyclic group, or a bicyclic fused heterocyclic group; and E represents 4H-1,2,4-triazolyl, 1H-1,2,4-triazolyl or 1H-1,2,3-triazolyl.
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- Selective electrolytic fluorinations in 70% HF/30% pyridine
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The selective fluorination of compounds containing benzylic hydrogen atoms was accomplished by electrolysis in a mixture of 70% HF and 30% pyridine (Olah's reagent) using a square wave alternating current (1.76-2.75 V, 0.02-0.05 Hz) and Pt electrodes. This method can be used in the laboratory to prepare conveniently gram-size quantities of monofluorinated products. An ion radical mechanism has been proposed.
- Lee, Sarah M.,Roseman, Jamie M.,Zartman, C. Blair,Morrison, Eamonn P.,Harrison, Sean J.,Stankiewicz, Corrie A.,Middleton
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- New Liquid Crystalline Compounds Based on 1,4-Diarylbuta-1,3-dienes
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The first group of fully characterised mesogenic (E,E)-1,4-diarylbuta-1,3-dienes, substituted in the para-position of one aryl ring by an alkoxy-group and in the para-position of the other aryl group by a cyano- or halogeno-group has been prepared by a Wadsworth-Emmons procedure; their physical properties of high birefringence and low viscosity in combination make them particularly suitable for use in liquid crystal display devices when mixed with known liquid crystalline materials.
- Brettle, Roger,Dunmur, David A.,Hindley, Nigel J.,Marson, Charles M.
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p. 410 - 411
(2007/10/02)
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- ORGANIC PHOSPHORUS COMPOUNDS 91. SYNTHESIS AND PROPERTIES OF 1-AMINO-2-ARYLETHYLPHOSPHONIC AND -PHOSPHINIC ACIDS AS WELL AS -PHOSPHINE OXIDES
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The preparation, physical and spectroscopic properties of 1-amino-2-arylethylphosphonic, and -phosphinic acids as well as -phosphine oxides, the phosphorus analogues of phenylalanine are described, and the reactions of 1-amino-2-(4-fluorophenyl)ethylphosphonates with acetals, isocyanides, esters, acid anhydrides, activated aromatic nitro- and halogen compounds, and with N-protected alanine are reported.It is shown that several of the 1-amino-2-arylethylphosphonic acids are strong inhibitors of PAL and anthocyanin synthesis and also are quite active botryticides.Among the active compounds were 1-amino-2-(4-fluorophenyl)ethylphosphonic acid, 3f, and the methyl-substituted compounds 3k, 3l, and 3m.The fluoroderivative 3f was also effective as a seed-dressing agent in barley showing a 100percent protection against the fungus Fusarium nivale at 600 ppm.
- Maier, Ludwig
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- POTENTIAL NEUROLEPTICS OF THE ORTHOPRAMIDE SERIES; SYNTHESIS OF N-SUBSTITUTED 5-(AMINOSULFONYL)-2-METHOXYBENZAMIDES
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The mixed anhydride of 5-(aminosulfonyl)-2-methoxybenzoic acid (VII) and monoethyl carbonate reacted with benzylamine, 1-methylpiperazine, and 1-benzylpiperazine to give the 5-(aminosulfonyl)-2-methoxybenzamides II, IV, and V.Heating the ethyl ester X with 4-amino-1-methylpiperidine resulted in the amide III.Reaction of 5-(chlorosulfonyl)-2-methoxybenzoyl chloride (XI) with 1-benzylpiperazine afforded 5-(4-benzylpiperazinosulfonyl)-2-methoxybenzoic acid 4-benzylpiperazide (VI).Compounds II-VI are analogues of the antidopaminergic and antiemetic agent sulpiride (I) but only the benzylpiperazides V and VI showed indications of psychotropic activity of the neuroleptic type.
- Valenta, Vladimir,Protiva, Miroslav
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p. 2095 - 2106
(2007/10/02)
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- The easy preparation of many benzylic bromides using molecular bromine as a halogenating in the presence of catalytic amounts of lanthanum tri-acetate
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Many benzylic brominations were easily achieved by molecular bromine in CCl4 in presence of 1 percent of La (OAc)3 and a standard room lighting lamp.The selectivity is excellent except for certain electron-rich systems (p-methylaniline, p-cresol).
- Ouertani, Mohsen,Girard, Pierre,Kagan, Henry B.
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p. 327 - 328
(2007/10/02)
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- Intramolecular Electron Transfer and Dehalogenation of Anion Radicals. 3. Halobenzonitriles and Cyanobenzyl Halides
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One-electron reduction of halobenzonitriles and cyanobenzyl halides produces the anion radicals which then undergo intramolecular electron transfer leading to dehalogenation.Kinetic spectrophotomethric pulse radiolysis allowed the observation of the halobenzonitrile anion radicals and the determination of their dehalogenation rates.The rates varied from 104 to >107 s-1 depending on the halogen and its position relative to cyano group.The production of X- was measured in steady-state radiolysis experiments, and the participation of cyanophenyl radicals as intermediates was also deduced from observation of chain reaction.The anion radicals of cyanobenzyl halides were not observed since they dehalogenate very rapidly.The cyanobenzyl radicals produced by this process were monitored spectrophotometrically.The rates of dehalogenation of the anion radicals studied here are at least 5 orders of magnitude higher than the corresponding values determined previously for analogous nitro derivatives, but the pattern of reactivities is similar in both series of radicals.
- Neta, P.,Behar, D.
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p. 103 - 106
(2007/10/02)
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