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Preparation of 1,5-Dihydropyrazolo[3′,4′:5,6]pyrano[3,4- b]pyridines via a Microwave-Assisted, Palladium-Catalyzed Regioselective C-H Heteroarylation of Electron-Rich Pyrazoles
Here we report the first synthesis of a family of novel heterocyclic compounds based on a 5-dihydropyrazolo[3′,4′:5,6]pyrano[3,4-b]pyridine core. In the course of our drug discovery programs, we had need to access the previously unknown 5-dihydropyrazolo[3′,4′:5,6]pyrano[3,4-b]pyridine core. Initial attempts required long reaction times, which led to degradation and side products. Reaction optimization identified a Pd-catalyzed, microwave-assisted C-H heteroarylation protocol for the rapid, general, and high yielding synthesis of this tricyclic core (as well as related analogs) suitable to drive optimization efforts.
Garrison, Aaron T.,Childress, Elizabeth S.,Davis, Dexter C.,Lindsley, Craig W.
p. 5855 - 5862
(2019)
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tBuOK-Promoted Cyclization of Imines with Aryl Halides
A transition-metal-free indole synthesis using radical coupling of 2-halotoluenes and imines via the later-stage C-N bond construction was reported for the first time. It includes an aminyl radical generation by C-H cleaving addition of 2-halotoluenes to imines via the carbanion radical relay and an intramolecular coupling of aryl halides with aminyl radicals. One standard condition can be used for all halides including F, Cl, Br, and I. No extra oxidant or transition metal is required.
Li, Ya-Wei,Zheng, Hong-Xing,Yang, Bo,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
supporting information
p. 4553 - 4556
(2020/06/08)

Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
supporting information
p. 10620 - 10625
(2020/07/24)

Design, synthesis and biological evaluation of low molecular weight CXCR4 ligands
The chemokine receptor CXCR4/stromal cell-derived factor-1 (SDF-1: CXCL12) signaling axis represents a crucial drug target due to its relevance to several diseases such as HIV-1 infection, cancer, leukemia, and rheumatoid arthritis. With the aim of enhancing the binding affinity and anti-HIV activity of a potent CXCR4 ligand as a lead, 23 low molecular weight compounds containing dipicolylamine (Dpa) and cyclam cationic moieties with varying spacers and spatial positioning were designed, synthesized and biologically evaluated. All of the synthesized compounds screened at 1.0 μM in the NanoBRET assay system exhibited >70% inhibition of the binding of a competitive probe TAMRA-Ac-TZ14011 (10 nM) to CXCR4 in the presence of zinc (II) ion. Furthermore, selected compounds 3, 8, 9, 19 and 21 with spatial distances between the next carbon to Dpa and the next carbon to cyclam within the range of 6.5–7.5 ? showed potent binding affinity selective for CXCR4 with IC50 values of 1.6, 7.9, 5.7, 3.5 and 4.5 nM, respectively, with corresponding high anti-HIV activity with EC50s of 28, 13, 21, 28 and 61 nM, respectively, in the presence of zinc (II) ion. Some compounds with remarkably more potent CXCR4-binding affinity than that of an initial lead were obtained. These compounds interact with different but overlapping amino acid residues of CXCR4. The present studies have developed new low molecular weight CXCR4 ligands with high CXCR4-binding and anti-HIV activities, which open avenue into the development of more potent CXCR4 ligands.
Sakyiamah, Maxwell M.,Kobayakawa, Takuya,Fujino, Masayuki,Konno, Makoto,Narumi, Tetsuo,Tanaka, Tomohiro,Nomura, Wataru,Yamamoto, Naoki,Murakami, Tsutomu,Tamamura, Hirokazu
supporting information
p. 1130 - 1138
(2019/02/16)

Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
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
supporting information
p. 4197 - 4204
(2018/09/25)

Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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
supporting information
p. 4933 - 4939
(2018/12/14)

Halogenation through Deoxygenation of Alcohols and Aldehydes
An efficient reagent system, Ph3P/XCH2CH2X (X = Cl, Br, or I), was very effective for the deoxygenative halogenation (including fluorination) of alcohols (including tertiary alcohols) and aldehydes. The easily available 1,2-dihaloethanes were used as key reagents and halogen sources. The use of (EtO)3P instead of Ph3P could also realize deoxy-halogenation, allowing for a convenient purification process, as the byproduct (EtO)3Pa?O could be removed by aqueous washing. The mild reaction conditions, wide substrate scope, and wide availability of 1,2-dihaloethanes make this protocol attractive for the synthesis of halogenated compounds.
Chen, Jia,Lin, Jin-Hong,Xiao, Ji-Chang
supporting information
p. 3061 - 3064
(2018/05/28)

Strategy for Overcoming Full Reversibility of Intermolecular Radical Addition to Aldehydes: Tandem C-H and C-O Bonds Cleaving Cyclization of (Phenoxymethyl)arenes with Carbonyls to Benzofurans
An intermolecular addition of carbon radicals enabled by a cascade radical coupling strategy is developed. It includes an intermolecular alkyl radical addition to a carbonyl group followed by an intramolecular alkoxy radical addition to haloarenes and produces substituted benzofurans in high yields. The radical nature of this reaction is explored by radical trapping experiments and EPR analysis. The mechanism is investigated by KIE experiments and control experiments. This method could provide rapid and practical access to the key intermediate of TAM-16, a safe and potent antibacterial agent for treating tuberculosis, and, therefore, is of great importance for organic synthesis and the pharmaceutical industry.
Zheng, Hong-Xing,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
supporting information
p. 3310 - 3313
(2018/06/11)

Copper powder-catalyzed coupling and cyclization of 1-bromoallyl bromides with amidine hydrochlorides leading to pyrimidines
1-Bromoallyl bromides are coupled and cyclized with amidine hydrochlorides in DMF at 130 °C in the presence of a catalytic amount of copper powder along with K3PO4 to give pyrimidines in moderate to good yields.
Lee, Ha Kyeong,Sohn, Ho-Sang,Cho, Chan Sik
supporting information
p. 1046 - 1051
(2017/05/25)

Preparation method of FSH (follicle-stimulating hormone) antagonist with benzopyran structure
The invention discloses a preparation method of an FSH (follicle-stimulating hormone) antagonist with a benzopyran structure, and belongs to the technical field of synthesis of medical intermediates. The technical scheme is mainly as shown in the description. The synthesis process is simple and low in cost, and the prepared FSH antagonist is good in action effect on FSH receptors after activity tests and can be further popularized and applied.
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Paragraph 0023; 0032; 0033

(2017/09/01)

Generation of α-imino gold carbenes through gold-catalyzed intermolecular reaction of azides with ynamides
The generation of α-imino gold carbenes via gold-catalyzed intermolecular reaction of azides and ynamides is disclosed. This new methodology allows for highly regioselective access to valuable 2-aminoindoles and 3-amino-β-carbolines in generally good to excellent yields. A mechanistic rationale for this tandem reaction, especially for the observed high regioselectivity, is supported by DFT calculations.
Shu, Chao,Wang, Yong-Heng,Zhou, Bo,Li, Xin-Ling,Ping, Yi-Fan,Lu, Xin,Ye, Long-Wu
supporting information
p. 9567 - 9570
(2015/08/18)

P(NMe2)3-Mediated Umpolung Alkylation and Nonylidic Olefination of α-Keto Esters
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.
supporting information
p. 3810 - 3813
(2015/08/18)

Clay-Supported Cu(II) Catalyst: An Efficient, Heterogeneous, and Recyclable Catalyst for Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Alloxan-Derived Terminal Alkyne and Substituted Azides Using Click Chemistry
A novel series of alloxan-derived 1,4-disubstituted 1,2,3-triazoles was synthesized in excellent yields under catalytic conditions using a click reaction strategy through 1,3-dipolar cycloaddition. Their structures have been ascertained on the basis of spectroanalytical and elemental analysis data. Synthesis of hybrid compounds with varying substitutions in the triazole ring was achieved by reaction between alloxan-derived terminal alkyne and a pertinent azide derivative in the presence of clay-Cu(II) as the catalyst in methanolic medium. Also, comparative evaluation of various catalytic systems [viz., CuI, CuSO4, CuI-zeolite, K10Ti, and clay-Cu(II)] was investigated. Of these catalytic systems, clay-Cu(II) was observed to be the best. The catalyst was recyclable for several runs without showing significant loss in its activity. The good selectivity, cost-efficiency, short reaction time, milder reaction conditions, and simple workup procedure are the added salient features of this synthetic protocol.
Dubey, Nitin,Sharma, Pratibha,Kumar, Ashok
p. 2608 - 2626
(2015/11/28)

One-pot transformation of methylarenes into aromatic aldehydes under metal-free conditions
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
p. 3402 - 3410
(2014/06/09)

CuI-catalyzed coupling of gem-dibromovinylanilides and sulfonamides: An efficient method for the synthesis of 2-amidoindoles and indolo[1,2-a] quinazolines
A Cu(I)-catalyzed, intermolecular protocol for the synthesis of 2-amidoindoles and tetrahydroindolo[1,2-a]quinazolines in shorter time and high yields is reported. The key highlight of this disclosure is the formation of 2-amidoindole and tetrahydroindolo[1,2-a]quinazoline moieties directly from gem-dibromovinylanilides and sulfonamides in a one-pot fashion through the in situ formation of ynamides followed by a base-promoted intramolecular hydroamidation.
Kiruthika, Selvarangam E.,Perumal, Paramasivan Thirumalai
p. 484 - 487
(2014/04/03)

Ti/Ni-mediated inter- and intramolecular conjugate addition of aryl and alkenyl halides and triflates
In this work, we show that the unique combination of a nickel catalyst and Cp2TiCl allows the direct conjugate addition of aryl and alkenyl iodides, bromides, and to a lesser extent, chlorides and triflates to α,β-unsaturated carbonyls at room temperature, without requiring the previous formation of an organometallic nucleophile. The reaction proceeds inter- and intramolecularly with good functional group compatibility, which is key for the development of free protecting group methodologies. Carbo- and heterocycles of five- and six-membered rings are obtained in good yields. Moreover, some insights about the mechanism involved have been obtained from cyclic voltammetry, UV-vis, and HRTEM measurements.
Marquez, Irene R.,Miguel, Delia,Millan, Alba,Marcos, M. Luisa,De Cienfuegos, Luis Alvarez,Campana, Araceli G.,Cuerva, Juan M.
p. 1529 - 1541
(2014/03/21)

Direct oxidative conversion of methylarenes into aromatic nitriles
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
supporting information
p. 4194 - 4197
(2013/09/12)

Double palladium-catalyzed synthesis of azepines
The synthesis of new 5H-pyridobenzazepine and 5H-dipyridoazepine compounds using as key step a palladium-catalyzed amination-cyclization reaction is reported. By choosing an appropriate combination of ligands and reactants under standardized reaction conditions, N- and S-tricyclic products can be prepared in one step from the appropriate stilbenes. Georg Thieme Verlag Stuttgart · New York.
Bo?inovi?, Nina,Opsenica, Igor,?olaja, Bogdan A.
p. 49 - 52
(2013/02/23)

Synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters from arylmethyl azides via a domino process
A convenient synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters via a domino process is described. The synthesis employs arylmethyl azides as the precursor which undergoes an acid-promoted rearrangement to give an N-aryl iminium ion. Following the addition with ethyl 3-ethoxyacrylate, intramolecular electrophilic aromatic substitution, elimination and subsequent oxidation, the quinoline products were obtained in moderate to excellent yields.
Tummatorn, Jumreang,Thongsornkleeb, Charnsak,Ruchirawat, Somsak,Gettongsong, Tanita
supporting information
p. 1463 - 1467
(2013/05/08)

Synthesis of benzyl bromides with hexabromoacetone: An alternative path to drug intermediates
A series of benzyl bromides were efficiently prepared from the corresponding alcohols with Br3CCOCBr3/PPh3 at low temperatures and under neutral conditions. The present protocol was applied to the heterocyclic analogues and to the successful synthesis of the precursor of the antiulcer drug omeprazole, thus furnishing an alternate, mild method for the preparation of these drug intermediates. A significant steric factor was observed throughout both series supporting a SN2 mechanism.
Joseph, Kara M.,Larraza-Sanchez, Isabel
experimental part
p. 13 - 16
(2011/02/25)

Benzylic bromination of toluene derivatives with boron tribromide
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
experimental part
p. 998 - 1003
(2010/05/18)

Microwave-promoted, one-pot conversion of alkoxymethylated protected alcohols into their corresponding nitriles, bromides, and iodides using [bmim][InCl4] as a green catalyst
The Lewis acid room temperature ionic liquid, [bmim][InCl4], was found to be an efficient and green catalyst for the highly chemoselective and one-pot conversion of MOM- or EOM-ethers into their corresponding nitriles, bromides, and iodides under microwave irradiation. The procedures are simple, rapid, and high yielding. The catalyst exhibited a remarkable reactivity and is reusable.
Mirjafari, Arsalan,Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza
supporting information; experimental part
p. 3274 - 3276
(2010/07/18)

LEWIS ACID CATALYZED HALOGENATION OF ACTIVATED CARBON ATOMS
A practical and efficient method for halogenation of activated carbon atoms using readily available /V-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.
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Page/Page column 28-29

(2008/06/13)

An efficient synthesis of benzyl bromides from aromatic aldehydes using polymethylhydrosiloxane and (bromodimethyl)sulfonium bromide or N-bromosuccinimide
Polymethylhydrosiloxane (PMHS) in combination with (bromodimethyl)sulfonium bromide or NBS has been utilized for the first time for reductive bromination of aromatic aldehydes at room temperature to afford the corresponding benzyl bromides in excellent yields.
Das, Biswanath,Srinivas, Yallamalla,Holla, Harish,Laxminarayana, Keetha,Narender, Ravirala
p. 6681 - 6683
(2008/03/12)

Side arm participation in lariat ether carboxylate-alkali metal cation complexes in solution
Lariat ether carboxylic acids of structure CECH2OCH 2C6H4-2-CO2H with crown ether (CE) ring sizes of 12-crown-4, 15-crown-5 and 18-crown-6 are prepared and converted into alkali metal-lariat ether carboxylate complexes. Absorptions for the diastereotopic benzylic protons in the 1H NMR spectra of the complexes in CDCl3 are utilized to probe the extent of side arm interaction with the crown ether-complexed metal ion as a function of the crown ether ring size and identity of the alkali metal cation.
Torun, Lokman,Robison, Thomas W.,Krzykawski, Jan,Purkiss, David W.,Bartsch, Richard A.
p. 8345 - 8350
(2007/10/03)

Iron-catalyzed homo-coupling of simple and functionalized arylmagnesium reagents
(Chemical Equation Presented) Iron-catalyzed homo-coupling of simple and functionalized arylmagnesium reagents is described. The reaction is highly chemoselective (CN, COOEt and NO2 groups are tolerated). The procedure was used to perform intramolecular couplings. This cyclization reaction is the key step of the total synthesis of the N-methylcrinasiadine.
Cahiez, Gerard,Chaboche, Christophe,Mahuteau-Betzer, Florence,Ahr, Mathieu
p. 1943 - 1946
(2007/10/03)

Lewis acid catalyzed highly selective halogenation of aromatic compounds
A simple and efficient procedure for the halogenation of aromatic compounds with NCS, NBS, NIS and NFSI in the presence of catalytic amount of ZrCl 4 is described. Chlorination, bromination, iodination and fluorination of various aromatic compounds are performed with high selectivity under mild reaction conditions. Georg Thieme Verlag Stuttgart.
Zhang, Yanhua,Shibatomi, Kazutaka,Yamamoto, Hisashi
p. 2837 - 2842
(2007/10/03)

Intramolecular 9-membered hydrogen bonding of 2-arylmethylphenols having carbonyl groups at 2′-position
Thermodynamic parameters of nine-membered intramolecular hydrogen bonding between carbonyl groups and phenolic hydroxyl groups of 2-arylmethylphenols having methoxycarbonyl, dimethylcarbamoyl, and formyl groups were determined by variable temperature 1H NMR studies and van't Hoff analysis. The enthalpy of the hydrogen bonding was related to the electron-withdrawing ability of the substituents on the phenol and the basicity of the carbonyl group. The entropy loss of the hydrogen bonding was dependent on the rotation freedom of the phenol group. The enthalpy of nine-membered intramolecular hydrogen bonding between carbonyl groups and phenolic hydroxyl groups of 2-arylmethylphenols was related to the electron-withdrawing ability of the substituents on the phenol and the basicity of the carbonyl group. The entropy loss was dependent on the rotation freedom of the phenol group.
Yoshimi, Yasuharu,Maeda, Hajime,Hatanaka, Minoru,Mizuno, Kazuhiko
p. 9425 - 9431
(2007/10/03)

Orientation and alkylation effects on cation-π interactions in aqueous solution
We have investigated the orientation dependence of the cation-π interaction between a phenyl ring and a pyridinium ring in the context of a flexible model system in water. Of the four possible positions of the pyridinium nitrogen, ipso, ortho, meta, and para, we found a variation in the interaction energy of about 0.75 kcal mol-1, with the stacking of the ipso-pyridinium ring providing the strongest interaction. The observed stability is attributed to the maximization of the electrostatic interaction, minimization of rotamers, and possible differences in hydration phenomena arising from alkylation.
Rashkin, Mark J.,Hughes, Robert M.,Calloway, Nathaniel T.,Waters, Marcey L.
p. 13320 - 13325
(2007/10/03)

A Convergent Method for the Synthesis of Highly Enantiomerically Enriched Cyclic Silanes with Silicon-Centered Chirality
A preparatively straightforward methodology has been developed which allows the assembly of silicon-containing carbocycles as mixtures of diastereomers with silicon as the sole center of stereogenic information. One-step construction of the chiral cyclic silanes is realized by reaction of equimolar amounts of a dibromide and a chirally modified dichlorosilane under Barbier conditions giving access to several monofunctionalized 1-sila-1,2,3,4-tetrahydronaphthalenes and a corresponding phenanthrene derivative. Facile large scale syntheses of 3-(2-bromoaryl)propyl bromides as well as dichlorosilanes have been elaborated. This highly convergent methodology relies on the novel (-)-menthyloxy-substituted dichlorosilanes, which have the chiral auxiliary for the subsequent optical resolution installed. These enantiopure dichlorosilanes are useful building blocks for a general and modular one-step approach to silanes with silicon-centered chirality since this strategy avoids the linear sequences reported in literature. The optical resolution has been exemplarily optimized for the 1-phenyl-1-sila-1,2,3,4- tetrahydronaphthalene derivative and the absolute configuration has been established by X-ray crystallography. The chiral auxiliary is stereospecifically displaced by simple reduction providing the highly enantioenriched silane (er = 98:2) which is enantiospecifically chlorinated as verified by a Walden inversion at silicon.
Oestreich, Martin,Schmid, Ulrike K.,Auer, Gertrud,Keller, Manfred
p. 2725 - 2739
(2007/10/03)

A simple and efficient iodination of alcohols on polymer-supported triphenylphosphine
A simple, mild, and high-yielding procedure for the iodination of allylic, benzylic, and other primary alcohols using a combination of iodine and imidazole on polymer-supported triphenyl phosphine is described.
Anilkumar, Gopinathan,Nambu, Hisanori,Kita, Yasuyuki
p. 190 - 191
(2013/09/06)

Medium-sized cyclophanes. Part 55. Synthesis and conformational studies of [2.1.1] orthocyclophanes
[2.1.1]Orthocyclophanes 2 are prepared by pyrolysis of the corresponding 2-thia[3.1.1]orthocyclophane 2,2-dioxides 9, which are prepared by the reaction of 1,2-bis(2-bromomethylbenzyl)benzenes 7 with Na2S in ethanol under high dilution conditions, followed by oxidation with m-chloroperbenzoic acid. The conformational studies on [2.1.1]orthocyclophanes 2, which adopt flexible saddle and crown structures in comparison with the corresponding 10,15-dihydro-5H-tribenzo[a,d,g]cyclononene ([1.1.1]orthocyclophane) 1, are discussed.
Yamato,Sakaue,Tanaka,Tsuzuki
p. 434 - 439
(2007/10/03)

Synthesis of some macrocycles/bicycles from bis(o-formylphenyl) selenide: X-ray crystal structure of bis(o-formylphenyl) selenide and the first 28-membered selenium containing macrocyclic ligand
Bis(o-formylphenyl) selenide (7) was synthesized using the ortholithiation methodology. The reaction of o-lithiobenzaldehyde acetal (5) with Se(dtc)2 (dtc=diethyldithiacarbamate) afforded bis(o-formylphenyl) selenide acetal (6) in good yield. The key starting material 7 was isolated as pale yellow solid upon refluxing 6 with concentrated HCl. The structure of 7 was solved in the monoclinic space group P2/c with cell constants a=8.0170(6) ?, b=8.4514(6) ? and c=17.5289(12) ?, Z=4. The condensation of 7 with diethylenetriamine yielded the novel macrocyclic ligand [C36H38N6Se2] 8 via metal-free dimerization. Crystals of 8 are monoclinic, space group C2/c with a=18.732(3) ?, b=8.6515(10) ?, c=22.590(3) ? and Z=4. Hydrogenation of macrocycle 8 provided the corresponding saturated tetraazamacrocycle [C36H46N6Se2] (9), protonation of which with HBr afforded [C36H52N6Se2Br6·H2O] (10). The two novel cryptands [C54H54N8Se3] (12) and [C54H54N8Te3] (13) were prepared from the reaction of tris(2-aminoethyl)amine (tren) and the chalcogenides (7) and bis(o-formylphenyl) telluride (11) respectively using cesium ion as the template.
Panda, Arunashree,Menon, Saija C.,Singh, Harkesh B.,Butcher, Ray J.
p. 87 - 94
(2007/10/03)

Optical resolution and configurational stability of selenoxides stabilized by intramolecular coordination
2-((Dimethylamino)methyl)phenyl alkyl (or aryl) selenoxides, configurationally stabilized by intramolecular coordination of an amino group to the selenium atom, were optically resolved into their enantiomeric isomers by means of high-performance liquid chromatography using an optically active column packed with amylosecarbamate derivative/silica gel. This is the first example of the isolation of optically pure selenoxides without bulky substituents and also the first isolation of optically pure alkyl aryl selenoxides. The absolute configuration of the (-)-isomers could be assigned to be the S-form by comparison of their specific rotations, circular dichroism spectra, and behavior on the optically active column with those of the sulfur analogue, prepared by Andersen's method. Racemization of the optically active selenoxides was accelerated not only in acidic solution but also in basic media. This result indicates there are two different mechanisms for their racemization in acidic and basic media. The stabilization energy of the selenoxides by the intramolecular coordination of an amino group to the selenium atom was estimated to be ca. 3 kcal mol-1 on the basis of variable-temperature 1H NMR measurements.
Shimizu, Toshio,Enomoto, Masao,Taka, Hideo,Kamigata, Nobumasa
p. 8242 - 8247
(2007/10/03)

HgCl2-Catalyzed Benzylation of 1-Aryl-1-propynes
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Ma, Shengming,Wang, Lisha
p. 3497 - 3498
(2007/10/03)

Triazolylated teritiary amine compound or salt thereof
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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(2008/06/13)

Selective Preparation of Polycyclic Aromatic Hydrocarbons. Part 7. A Preparative Route to 10,11-Dihydro-5H-dibenzo-cycloheptenes Using Friedel-Crafts Intramolecular Cyclobenzylation
Cyclobenzylation of 2-hydroxymethyldiphenylethanes 4 and 2,2'-bis(hydroxymethyl)diphenylethanes 13 in the presence of a solid perfluorinated sulfonic acid resin, Nafion-H, as a catalyst results in novel polycyclic aromatic hydrocarbons, dibenzocyclopentenes.Dibenzocyclopentenes were also prepared from diphenylethanes by a benzylation reaction, which incorporates chloromethylation of a hydrocarbon followed by Friedel-Crafts intramolecular cyclization reaction.The present method involving the action of ClCH2OMe and TiCl4 on a variety of diphenylethanes (constructed such that electrophilic substitution occurs ortho to the diphenylethane linkage) offers a convenient, mild one-pot synthesis of substituted dibenzocycloheptenes.The mechanism of these reactions is also discussed.
Yamato, Takehiko,Sakaue, Naozumi,Komine, Masayasu,Nagano, Yoshiaki
p. 1708 - 1735
(2007/10/03)

Phosphane ligands with two binding sites of differing hardness for enantioselective Grignard cross coupling
A series of new, chiral phosphanes is presented, individual members of which were designed to serve as ligands in transition-metal mediated asymmetric Grignard cross coupling reactions. These ligands are characterized by a side chain containing one or two oxygen atoms with the capacity to act as binding sites for the incoming Grignard reagent. A number of structural parameters for the compounds was varied to learn about the reaction mechanism. Most of the ligands were tested in two cross coupling reactions, the formation of 3-phenylbut-1-ene and of 2,2′-dimethyl-1,1′-binaphthyl, respectively. Although both systems gave modest enantiomeric excesses it was not possible to make a comparison of their respective abilities.
Terfort, Andreas,Brunner, Henri
p. 1467 - 1479
(2007/10/03)

The preparation of heterobiaryl phosphonates via the Stille coupling reaction
The Stille cross-coupling reaction between various heteroarylstannanes and substituted bromo-benzylphosphonates was used to prepared heterobiaryl phosphonates in moderate to good yields.
Kennedy, Gordon,Perboni, Alcide D.
p. 7611 - 7614
(2007/10/03)

Studies in the Cycloproparene Series: Reactions with Radicals
The behaviour of 1H-cyclopropabenzene (1) and 1H-cyclopropanaphthalene (23) towards a variety of radicals results in opening of the three-membered ring to give ortho-substituted benzyl and 2-methylnaphthalene derivatives, e.g. (13) and (28), respectively.Ring expansion into the cycloheptatriene manifold by way of addition to the bridge bond and norcaradiene formation have not been observed.Analogous reactions with the methylidenecyclopropanaphthalenes (33) and (34) lead to much decomposition, and provide little evidence for the C 1 cycloproparenyl radicals (35) and (36).
Chai, Christina L. L.,Christen, Detlev,Halton, Brian,Neidlein, Richard,Starr, Malcolm A. E.
p. 577 - 592
(2007/10/02)

Facile Photochemical Synthesis of Benzylphosphines
Facile large-scale synthesis of the benzyl-dibromo-phosphines RPBr2 (R = C6H5CH2, 3,5-Me2C6H3CH2, 2-BrC6H4CH2) is accomplished by the photochemical reaction of toluene, mesitylene and 2-bromotoluene, respectively, with PBr3 in the absence of solvent.It the reactions are carried out up to 50percent completion the amount of by-products formed is remarkably low, rarely exceeding 10percent of the total amount of products formed.The selectivity of the photoreaction may be improved up to 98percent if it is carried out in a modified Soxhlet apparatus which allows the predominant irradiation of only the starting materials.The apparent limitations imposed by the low turnovers required to achieve good products formed in a short period of time and by the easy recovery of unreacted starting material by distillation.Thus in the case of 2-BrC6H4CH2PBr2, in a typical run 94 g (261 mmol) of product may be isolated after 2.5 h of irradiation of 970 mmol of 2-BrC6H5CH3 and 1.39 mol of PBr3.In this case the turnover is 32percent, the isolated yield 27percent, and the by-product 2-methylphenyl-dibromo-phosphine only amounts to less than 2percent.The benzyl-dibromo-phosphines are easily methylated with two equivalents of MeMgCl to give the respective benzyl-dimethyl-phosphines in 79-93percent yield.Tertiary benzylphosphines MePRR' (R = 2-BrC6H4CH2, R' = Me3SiCH2; R = R' = 2-BrC6H4CH2) are obtained in easy one-pot syntheses by consecutive reactions of 2-BrC6H4CH2PBr2 with Me3SiCH2MgCl and MeMgCl, and with 2-BrC6H4CH2MgBr and MeMgCl, respectively. - Keywords: Benzylphosphines, Photochemical Synthesis
Mueller, Gerhard,Waldkircher, Martin,Winkler, Martin
p. 1606 - 1614
(2007/10/02)

Enantioselective catalysis, 85 [1]. Optically active expanded chelate phosphines derived from 1,ω-bis(dichlorophosphino)alkanes
Optically active expanded chelate phosphines were synthesised by reaction of bromotolyl, bromoxylyl and bromodiphenylmethane derivatives with 1,ω- bis(dichlorophosphino)alkanes. The bromotolyl, bromoxylyl and bromodiphenylmethane ethers were obtained from the corresponding bromo(1bromomethyl)arenes and the optically active alcohol (-)-borneol.
Brunner,Furst
p. 4303 - 4310
(2007/10/02)

Preparation of 2-(2-thienyl) ethylamine and synthesis of thieno [3,2-C] pyridine derivatives therefrom
Compounds of the formulae:and wherein:, R1, R2, R3 and R4 are independently hydrogen, lower alkyl of one to six carbon atoms, aryl or substituted aryl;, are advantageously converted to isocyanurate compounds, 2-(2-thienyl)ethylamine compounds and thieno[3,2-c]pyridine derivatives and the pharmaceutically acceptable salts thereof, particularly ticlopidine hydrochloride.
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(2008/06/13)

Organic Reactions Catalyzed by Solid Superacids. 9. Friedel-Crafts Cyclobenzylation of Benzene with Bis-(hydroxymethyl)diarylalkanes Catalyzed by a Perfluorinated Sulfonic Acid Resin (Nafion-H)
Cyclobenzylation of benzene using bis(hydroxymethyl)diarylmethanes (6) and bis(hydroxymethyl)diarylaethanes (14) in the presence of solid perfluorinated sulfonic acid resin, Nafion-H, as a catalyst results in novel bridged aromatic compounds, 10,15-dihydro-5H-tribenzocyclononenes (15) and metacyclophanes (17), respectively.The reactions were clean, and water that was formed as a by-product did not deactivate the catalyst.It was also found that cyclobenzylation products, methacyclophanes were not formed via the isomerization of the corresponding orthomethacyclophane (19) under the reaction conditions used.The posible mechanism of the reaction is also discussed.
Yamato, Takehiko,Sakaue, Naozumi,Furusawa, Takashi,Tashiro, Masahi,Prakash, G.K.Surya,Olah, George A.
p. 2414 - 2438
(2007/10/02)

2-(2-nitrovinyl)thiophene reduction and synthesis of thieno[3,2-c]pyridine derivatives
An improved process for the reduction of 2-(2-nitrovinyl)thiophene to form 2-(2-thienyl)ethylamine employs a boron-containing reducing agent, preferably diborane. The 2-(2-thienyl)ethylamine produced by this process is advantageously converted to ticlopidine.
-
(2008/06/13)

Organoinsecticide synergists. Part I. Synthesis of substituted-benzyl-2-propynyl ethers and their synergistic activity
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Krishna Moorthy
p. 909 - 911
(2007/10/02)

Bromination of α-Substituted Alkylbenzenes: Synthesis of (p-Bromophenyl)acetylene
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Dakka, Jihad,Sasson, Yoel
p. 3224 - 3226
(2007/10/02)

Photochemistry of chloro-2-vinylstilbenes
Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds.Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol.At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclohex-2-ene (39) is formed formed from 20.The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41).The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38).However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo-hex-2-ene (40).This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule.It is shown that both isomers of 22 can photocyclize into 40.
Brouw, P. M. op den,Laarhoven, W. H.
p. 58 - 67
(2007/10/02)

CUPRIC BROMIDE AS BENZYLIC BROMINATION REAGENT IN POLAR MEDIA
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Chaintreau, Alain,Adrian, Guy,Couturier, Daniel
p. 669 - 672
(2007/10/02)

SYNTHESIS AND CHEMISTRY OF THE PHENOXASILINS AND DIHYDRO-DIBENZO-OXASILEPINS
Formation of both sila-functional and carbo-functional phenoxasilins from diphenyl ether and o,o'-dibromodiphenyl ether precursors is described.Tricyclic oxasilepins are formed from o,o'-dibromobenzylphenyl ether by metallation with n-BuLi followed by reaction with dichlorosilanes as well as by ring expansion of an appropriate phenoxasilin.Reactions at the silicon center and at the ring methylene carbon of the oxasilepins are reported, as well as attempts to generate oxasilocins.
Chang, V. H. T.,Corey, J. Y.
p. 217 - 227
(2007/10/02)