- Unusually Long Lifetimes of the Singlet Derived from 4-Azido-2,3,5,6-tetrafluorobenzamides
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Laser flash photolysis (308 nm, 20 ns, 150 mJ) of 4-azido-2,3,5,6-tetrafluorobenzamides, esters, and thioesters generate singlet nitrenes which can be intercepted with pyridine to produce strongly absorbing ylides.It was possible to resolve the rate of formation of the ylides as a function of pyridine concentration.This has lad to direct measurements of the absolute rate constants of (a) the reaction of the nitrene with pyridine, (b) ring expansion of the nitrene to a ketenimine, and (c) singlet to triplet nitrene intersystem crossing.
- Marcinek, Andrzej,Platz, Matthew S.,Chan, Stephen Y.,Floresca, Rey,Rajagopalan, Krishnan,et al.
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- The oxidation of alcohols to aldehydes and ketones with N-bromosuccinimide in polyethylene glycol: An experimental and theoretical study
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Oxidation of aliphatic and aromatic alcohols has been studied by using N-bromosuccinimide (NBS) as oxidant and polyethylene glycol (PEG) as reaction medium under mild reaction conditions. Temperature and solvent effect are studied. Theoretical study is also done with the Gaussian 98 suite of program and the calculation results are in good accordance with the experimental outcome. This system offers a very clean, convenient, environmentally benign method for the oxidation of alcohols. Copyright
- Fan, Ji-Cai,Shang, Zhi-Cai,Liang, Jun,Liu, Xiu-Hong,Liu, Yang
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- Reactivity of chlorinating agents/PPh3 for the chlorination of alcohols and carboxylic acids: a comparative study
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The reactivity of chlorinating agents was examined with the aid of 1H NMR using competitive reactions between selected chlorinating agents and CBr4 towards alcohols and carboxylic acids. The reactivity was greatly dependent on the type of substituent on the chlorinating agents. COCCl3 and CN substituted trichloromethyl groups enhanced the reactivity of the chlorinating agent with PPh3 for the chlorination of alcohols and carboxylic acids.
- Pluempanupat, Wanchai,Chantarasriwong, Oraphin,Taboonpong, Piyada,Jang, Doo Ok,Chavasiri, Warinthorn
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- Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system
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An oxidation system comprising phenyliodine(III) diacetate (PIDA) and iodosobenzene with inorganic bromide, i.e., sodium bromide, in an organic solvent led to the direct introduction of carboxylic acids into benzylic C–H bonds under mild conditions. The unique radical species, generated by the homolytic cleavage of the labile I(III)–Br bond of the in situ-formed bromo-λ3-iodane, initiated benzylic carboxylation with a high degree of selectivity for the secondary benzylic position.
- Dohi, Toshifumi,Iwasaki, Kosuke,Kita, Yasuyuki,Morimoto, Koji,Tsunoda, Yusuke,Ueda, Shohei
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- Evolution of a 4-Benzyloxy-benzylamino Chemotype to Provide Efficacious, Potent, and Isoform Selective PPARα Agonists as Leads for Retinal Disorders
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Peroxisome proliferator-activated receptor alpha (PPARα) is expressed in retinal Müller cells, endothelial cells, and in retinal pigment epithelium; agonism of PPARα with genetic or pharmacological tools ameliorates inflammation, vascular leakage, neurodegeneration, and neovascularization associated with retinal diseases in animal models. As such, PPARα is a promising drug target for diabetic retinopathy and age-related macular degeneration. Herein, we report proof-of-concept in vivo efficacy in an streptozotocin-induced vascular leakage model (rat) and preliminary pharmacokinetic assessment of a first-generation lead 4a (A91). Additionally, we present the design, synthesis, and evaluation of second-generation analogues, which led to the discovery of 4u and related compounds that reach cellular potencies 2,700-fold selectivity for PPARα over other PPAR isoforms. These studies identify a pipeline of candidates positioned for detailed PK/PD and pre-clinical evaluation.
- Dou, Xiaozheng,Nath, Dinesh,Shin, Henry,Nurmemmedov, Elmar,Bourne, Philip C.,Ma, Jian-Xing,Duerfeldt, Adam S.
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- Approach to Comparing the Functional Group Tolerance of Reactions
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Herein, we describe an approach to quantifying and comparing functional group (FG) tolerance of synthetic reactions. Additive-based reaction screening is utilized as a tool for the objective comparison of reaction conditions as demonstrated in four case studies. This contributes to an understanding of factors limiting a reaction's FG tolerance and the identification of truly mild reactions.
- Gensch, Tobias,Teders, Michael,Glorius, Frank
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- Photolytic generation of carbon radicals from Barton esters: Recent developments
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O-Acyl derivatives of N-hydroxy-2-thiopyridone can be photolysed with suitable commercial visible-light lamps to give reactions with very short half-lives (down to 20 s) at 0° C or room temperature.
- Barton,Jaszberenyi,Tang
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- REACTIONS OF BrCl WITH ALKYL RADICALS.
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It is demonstrated that photohalogenation of low reactivity substrates with BrCl occurs mainly with Cl. selectivity.With tertiary or benzylic hydrogens in the substrate, mainly Br. selectivity is observed.These observations are rationalized, taking into account the relative concentrations of halogen atoms and their respective rates of hydrogen abstractions.The resultant radicals react with BrCl to make (RBr/RCl) in ratios between 1 and 15.
- Skell, P. S.,Baxter, H. N.,Tanko, J. M.
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- Scalable anti-Markovnikov hydrobromination of aliphatic and aromatic olefins
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To improve access to a key synthetic intermediate we targeted a direct hydrobromination-Negishi route. Unsurprisingly, the anti-Markovnikov addition of HBr to estragole in the presence of AIBN proved successful. However, even in the absence of an added initiator, anti-Markovnikov addition was observed. Re-examination of early reports revealed that selective Markovnikov addition, often simply termed "normal" addition, is not always observed with HBr unless air is excluded, leading to the rediscovery of a reproducible and scalable initiator-free protocol.
- Galli, Marzia,Fletcher, Catherine J.,Del Pozo, Marc,Goldup, Stephen M.
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- α-Bromo Carbonyl Compounds as Promoters for the Synthesis of (2-Bromoethyl)benzene by the Anti-Markovnikov Addition of Hydrogen Bromide to Styrene
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The synthesis of (2-bromoethyl)benzene by the anti-Markovnikov addition of gaseous hydrogen bromide to styrene has been found to be promoted by α-bromo carbonyl compounds such as 2-bromo-2-methylpropanal.These compounds were found to catalyze the "abnormal" addition in a variety of solvents such as ethyl acetate, heptane, toluene and dioxane.High concentrations of 2-bromo-2-methylpropanal and hydrogen bromide and low concentrations of styrene favor formation of (2-bromoethyl)benzene.Using the free-radical catalyzed cyclization of 6-bromo-1-hexene as a probe we have found that the 2-bromo-2-methylpropanal does not in itself initiate a free-radical chain reaction by thermal formation of radicals.Instead, radicals may react with 2-bromo-2-methylpropanal to form relatively stable 2-methylpropanal radicals.The presence of such radicals increases the effective length or inhibits termination of the free-radical chain reaction (propagation) and in the case of hydrobromination of styrene raises the yield of (2-bromoethyl)benzene.
- Neumann, Ronny,Vega, Fernando de la,Bar-On, Adva
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- Regio- and stereoselective synthesis of bromoalkenes by homolytic hydrobromination of alkynes with hydrogen bromide
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Homolytic hydrobromination of terminal and internal alkynes with a commercially available solution of hydrogen bromide in acetic acid has been investigated for regio- and stereoselective synthesis of bromoalkenes. Under an aerobic atmosphere at room temperature, the reaction of ethynylarenes with a small excess of HBr efficiently gave (2-bromoethenyl)arenes with good to high E-selectivity. (Alk-1-ynyl)arenes, or internal alkynes bearing both phenyl and alkyl groups at the sp-carbons also underwent the air-initiated hydrobromination to exhibit high Z-selectivity under kinetic conditions using a half equivalent of HBr.
- Kumaki, Wataru,Kinoshita, Hidenori,Miura, Katsukiyo
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supporting information
(2022/03/07)
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- 1,3-Diphenyldisiloxane Enables Additive-Free Redox Recycling Reactions and Catalysis with Triphenylphosphine
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The recently reported chemoselective reduction of phosphine oxides with 1,3-diphenyldisiloxane (DPDS) has opened up the possibility of additive-free phosphine oxide reductions in catalytic systems. Herein we disclose the use of this new reducing agent as an enabler of phosphorus redox recycling in Wittig, Staudinger, and alcohol substitution reactions. DPDS was successfully utilized in ambient-temperature additive-free redox recycling variants of the Wittig olefination, Appel halogenation, and Staudinger reduction. Triphenylphosphine-promoted catalytic recycling reactions were also facilitated by DPDS. Additive-free triphenylphosphine-promoted catalytic Staudinger reductions could even be performed at ambient temperature due to the rapid nature of phosphinimine reduction, for which we characterized kinetic and thermodynamic parameters. These results demonstrate the utility of DPDS as an excellent reducing agent for the development of phosphorus redox recycling reactions.
- Buonomo, Joseph A.,Cole, Malcolm S.,Eiden, Carter G.,Aldrich, Courtney C.
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p. 3583 - 3594
(2020/09/15)
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- A General Approach to Deboronative Radical Chain Reactions with Pinacol Alkylboronic Esters
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The generation of carbon-centered radicals from air-sensitive organoboron compounds through nucleohomolytic substitution at boron is a general method to generate non-functionalized and functionalized radicals. Due to their reduced Lewis acidity, alkylboronic pinacol esters are not suitable substrates. We report their in situ conversion into alkylboronic catechol esters by boron-transesterification with a substoichiometric amount of catechol methyl borate combined with an array of radical chain processes. This simple one-pot radical-chain deboronative method enables the conversion of pinacol boronic esters into iodides, bromides, chlorides, and thioethers. The process is also suitable the formation of nitriles and allylated compounds through C?C bond formation using sulfonyl radical traps. The power of combining radical and classical boron chemistry is illustrated with a modular 5-membered ring formation using a combination of three-component coupling and protodeboronative cyclization.
- André-Joyaux, Emy,Kuzovlev, Andrey,Renaud, Philippe,Tappin, Nicholas D. C.
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p. 13859 - 13864
(2020/06/10)
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- Thiourea-Mediated Halogenation of Alcohols
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The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
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p. 12901 - 12911
(2020/11/26)
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- 1,2-Dibromotetrachloroethane: An efficient reagent for many transformations by modified Appel reaction
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An efficient and facile method has been developed for the synthesis of alkyl bromides from various alcohols under mild conditions using a triphenylphosphine (PPh 3) /1,2-dibromotetrachloroethane (DBTCE) complex in excellent yields and very short time (5 min). This method can also be applied for the transformation of chiral alcohols to their corresponding bromides in very high enantiomeric excess. The PPh 3 /DBTCE complex is also successfully applied to ring-opening reactions of cyclic ethers in mild conditions. Esterification, amidation, and formation of acid anhydrides under very mild experimental conditions are also successfully accomplished by following a modification of the Appel reaction protocol in this work.
- Essiz, Sel?uk,Da?tan, Arif
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p. 150 - 156
(2019/05/16)
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- Visible Light-Mediated Conversion of Alcohols to Bromides by a Benzothiadiazole-Containing Organic Photocatalyst
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The search for metal-free, stable and high effective photocatalysts with sufficient photo-redox potentials remains a key challenge for organic chemists. Here, we present a benzothiadiazole-containing molecular organic photocatalyst with redox potentials of ?1.30 V and +1.64 V vs. SCE. The singlet state lifetime is 13 ns. Direct conversion from aliphatic alcohols to bromides has been conducted with the designed organic photocatalyst under visible light irradiation with high efficiency and selectivity. The catalytic efficiency of the novel benzothiadiazole-based photocatalyst is comparable with the state-of-art metal and non-metal catalysts. Furthermore, advanced photophysical studies including time-resolved photoluminescence and transient absorption spectroscopy offer a powerful support for photo-induced electron transfer from photocatalyst to the reactive substrates. Lastly, no photo-bleaching effect is observed, demonstrating the high stability and recyclable of the designed organic photocatalyst. (Figure presented.).
- Li, Run,Gehrig, Dominik W.,Ramanan, Charusheela,Blom, Paul W. M.,Kohl, Fabien F.,Wagner, Manfred,Landfester, Katharina,Zhang, Kai A. I.
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p. 3852 - 3859
(2019/07/15)
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- Promotion of Appel-type reactions by N-heterocyclic carbenes
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N-Heterocyclic carbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches the chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at the catalytic level using an NHC-oxide derivative is also investigated.
- Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 7962 - 7965
(2019/07/12)
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- Synthesis method of p-chloromethyl styrene
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The invention relates to a synthesis method of an organic intermediate, in particular, a synthesis method of p-chloromethyl styrene. According to the synthesis method, a phase-transfer catalytic method is adopted; p-chloromethyl-alpha-bromoethylbenzene and potassium hydroxide are taken as the raw materials; toluene is taken as the solvent; and a phase-transfer catalysis is added to synthesize p-chloromethyl styrene. The synthesis method has the advantages that the reactions are mild, the energy consumption is low, no high pressure or high temperature is needed during the reaction process, thereactants do not react with the solvent or the phase-transfer catalyst, the yield is increased, the side reactions are reduced, and a high quality product is obtained.
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Paragraph 0043-0044
(2019/11/25)
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- Palladium-Catalyzed Cascade Annulation/Allylation of Alkynyl Oxime Ethers with Allyl Halides: Rapid Access to Fully Substituted Isoxazoles
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A novel and efficient approach for the synthesis of functionalized isoxazoles via palladium-catalyzed cascade annulation/allylation of alkynyl oxime ethers with allyl halides has been established. The present protocol exhibits mild reaction conditions, good functional group compatibility, and convenient operation. Moreover, scalability was performed and further decoration of the isoxazole product was achieved.
- Li, Can,Li, Jianxiao,Zhou, Fei,Li, Chaosheng,Wu, Wanqing
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p. 11958 - 11970
(2019/10/11)
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- BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
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For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
- Li, Xuan,He, Jianghua,Zhang, Yuetao
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supporting information
p. 11019 - 11027
(2018/09/06)
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- Synthesis and Transformations of Aryl-Substituted Alkenes of the Adamantane Series
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Aryl-substituted alkenes of the adamantane series, 1-[(Z,E)-3-phenylprop-2-en-1-yl]adamantane and 1-[(Z)-3-phenylprop-1-en-1-yl]adamantane, have been synthesized by the Wittig reaction. Their allylic bromination involves two concurrent reactions, radical substitution and raical addition. The different chemical behaviors of the aryl-substituted alkenes have been demonstrated in the Ritter reaction. Depending on the alkene structure and acid catalyst nature, the products are secondary amides, sulfonic acid derivatives, and homoadamantane γ-sultone.
- Savel’eva,Leonova,Baimuratov,Klimochkin, Yu. N.
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p. 996 - 1002
(2018/09/12)
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- By nucleophilic substitution reaction to degrade lignin and lignin model compounds (by machine translation)
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The invention through the nucleophilic substitution reaction to degrade lignin and lignin model compound method relates to biomass energy chemical technical field. In order to lignin model compounds and organic solvent-soluble lignin as substrate, to halogenated compound B BX3 As nucleophiles, through the nucleophilic substitution reaction, in - 78 °C to 60 °C conditions, reaction 0.5 h - 36 h, at the same time realize lignin model compound, lignin degradation, and the connection of the X substituent. The operation of the invention the method is simple, mild reaction conditions, not only high conversion and high selectivity (>99% conversion rate, close to 99% [...] selective) realizes the lignin and the degradation of lignin model compound, and obtained the degradation product, is a very high can be modified with the nature contains the bromine compound, can be used as an important organic synthetic intermediates. (by machine translation)
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Paragraph 0070; 0071
(2018/04/03)
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- Sulfonyl halide synthesis by thiol oxyhalogenation using NBS/NCS – iPrOH
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A rapid and facile method provides a general route to sulfonyl bromides/chlorides by the oxidation of thiols using NXS – ROH (X?=?Br,Cl, R?=?iPr) as an oxyhalogenation reagent. Control experiments suggest that the alcohol component is the source of oxygen. The proposed method enable the access to structurally diverse sulfonyl bromides and chlorides including challenging examples, inaccessible by other synthetic methods.
- Silva-Cuevas, Carolina,Perez-Arrieta, Carlos,Polindara-García, Luis A.,Lujan-Montelongo, J. Armando
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p. 2244 - 2247
(2017/05/16)
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- HBr–DMPU: The First Aprotic Organic Solution of Hydrogen Bromide
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HBr and DMPU (1,3-dimethyl-3,4,5,6-tetrahydro-2-pyrimidinone) form a room-temperature-stable complex that provides a mild, effective, and selective hydrobrominating reagent toward alkynes, alkenes, and allenes. HBr–DMPU could also replace other halogenating reagents in the halo-Prins reaction, ether cleavage, and deoxy-bromination reactions.
- Li, Zhou,Ebule, Rene,Kostyo, Jessica,Hammond, Gerald B.,Xu, Bo
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p. 12739 - 12743
(2017/09/25)
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- Bent-core mesogens with an aromatic unit at the terminal position
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Bent-core liquid crystals with a naphthalene central unit and an aromatic ring at the terminal position of molecular tails were synthesised with the aim of enhancing nanosegregation. It was found that the length of the spacer between the rigid core and the terminal aromatic moiety had a profound influence on the liquid crystal polymorphism. The homologues with short spacers exhibited nematic and columnar phases, whereas the homologue with long spacers exhibited a tilted lamellar phase with a liquid-like in-plane order, indicating an unusual morphology of the densely packed toroidal objects. The morphology can be changed to twisted ribbons by small additives adsorbed on the membrane surface. This is the first example of twisted ribbons constructed by a lamellar system with no long-range in-plane order.
- Bajzíková, Kvetoslava,Svoboda, Ji?í,Novotná, Vladimíra,Pociecha, Damian,Gorecka, Ewa
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supporting information
p. 4672 - 4679
(2017/07/10)
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- A novel route to the synthesis of α,Ω-diphenylalkanes
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A novel route to the synthesis of α,ω-diphenylalkanes is reported. Toluene was metalated in the benzylic position by n-butyllithium with THF as an activating reagent, and then directly reacted with α,ω-dichloroalkanes to obtain the target product. This process provides a facile and efficient route to the synthesis of α,Ω-diphenylalkanes.
- Chen, Hui,Chen, Yancai,Zhang, Yinlong,Yang, Zhenqiang,Li, Ji,Yang, Ruina,Wang, Wenxin
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p. 473 - 474
(2017/08/18)
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- Visible-light photoredox catalysis using a macromolecular ruthenium complex: Reactivity and recovery by size-exclusion nanofiltration in continuous flow
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A novel macromolecular photoredox catalyst based on [Ru(bpy)3]2+ anchored to a 2nd-generation PAMAM dendrimer has been developed. Its catalytic activity under visible light irradiation and recyclability using organic solvent nanofiltration with a size-exclusion membrane have been explored under continuous flow conditions.
- Guerra, Javier,Cantillo, David,Kappe, C. Oliver
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p. 4695 - 4699
(2016/07/11)
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- Catalytic halodefluorination of aliphatic carbon-fluorine bonds
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A variety of halosilanes, in conjunction with aluminum catalysts, convert fluorocarbons into higher halocarbons. Bromination and iodination of fluorocarbons are more effective than chlorination in terms of yield and activity. The mechanism for the reaction is investigated utilizing experimental and computational evidence and preliminary results suggest an alternate mechanism to that reported for the related hydrodefluorination reaction.
- Goh, Kelvin K.K.,Sinha, Arup,Fraser, Craig,Young, Rowan D.
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p. 42708 - 42712
(2016/05/19)
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- Construction of chiral 2-substituted octahydroindoles from cyclic ketones and nitroolefins bearing only one α-substituent
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A dual catalytic system has been developed following the screening of a series of chiral primary amine catalysts and chiral phosphoric acid catalysts for the Michael addition of cyclic ketones to nitroolefins bearing only one α-substituent. The resulting γ-nitro ketones, which contain a substituent on the carbon connected to the nitro group, were formed in excellent yields (>80%) with high levels of stereoselectivity (up to 94:6 dr and 98% ee) when the reaction was performed in benzene at 0 °C with 10 mol% of the optimal amine/phosphoric acid combination (1:1) as a catalyst. Subsequent reduction of the nitro group followed by intramolecular reductive amination could afford optically active cis-octahydroindole analogues bearing a non-functional substituent at their 2-position.
- Han, Yong,Zheng, Bo,Peng, Yungui
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supporting information
p. 1136 - 1142
(2015/04/22)
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- Bimodal ligands with macrocyclic and acyclic binding moieties, complexes and compositions thereof, and methods of using
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Substituted 1,4,7-triazacyclononane-N,N′,N″-triacetic acid and 1,4,7,10-tetraazacyclcododecane-N,N′,N″,N′″-tetraacetic acid compounds with a pendant amino or hydroxyl group, metal complexes thereof, compositions thereof, and methods of making and use in diagnostic imaging and treatment of cellular disorders.
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Page/Page column 109; 110; 137 - 139
(2015/09/23)
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- Aromatic cation activation: Nucleophilic substitution of alcohols and carboxylic acids
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A new method for the nucleophilic substitution of alcohols and carboxylic acids using aromatic tropylium cation activation has been developed. This article reports the use of chloro tropylium chloride for the rapid generation of alkyl halides and acyl chlorides under very mild reaction conditions. It demonstrates, for the first time, the synthetic potential of tropylium cations in promoting chemical transformations.
- Nguyen, Thanh V.,Bekensir, Alp
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supporting information
p. 1720 - 1723
(2014/04/17)
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- Tribromoisocyanuric acid/triphenylphosphine: A new system for conversion of alcohols into alkyl bromides
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An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/ tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzylic and allylic alcohols, and their corresponding bromides are obtained in 67-82 percent yield. Tertiary alcohols do not react under these conditions.
- De Andrade, Vitor S.C.,De Mattos, Marcio C.S.
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p. 975 - 979
(2014/06/24)
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- A novel method to access chiral nonnatural 2,4-disubstituted pyrrolidines from aldehydes and nitroolefins only with an α-substituent
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A series of α-substituted nitroolefins were employed in organocatalytic asymmetric Michael reactions with aldehydes. γ-Nitro carbonyl products were achieved in good yields (up to 86%) with good stereoselectivities (up to 96% ee and 24 : 1 dr). Reduction of the nitro group followed by intramolecular reductive amination successfully afforded various novel optically active 2,4-disubstituted pyrrolidine compounds.
- Zheng, Bo,Wang, Hui,Han, Yong,Liu, Changlu,Peng, Yungui
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supporting information
p. 4561 - 4563
(2013/06/04)
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- Discovery of a new class of potent MMP inhibitors by structure-based optimization of the arylsulfonamide scaffold
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A new class of potent matrix metalloproteinase (MMP) inhibitors designed by structure-based optimization of the well-known arylsulfonamide scaffold is presented. Molecules show an ethylene linker connecting the sulfonamide group with the P1' aromatic portion and a D-proline residue bearing the zinc-binding group. The affinity improvement provided by these modifications led us to discover a nanomolar MMP inhibitor bearing a carboxylate moiety as zinc-binding group, which might be a promising lead molecule. Notably, a significant selectivity for MMP-8, MMP-12, and MMP-13 was observed with respect to MMP-1 and MMP-7.
- Mori, Mattia,Massaro, Assunta,Calderone, Vito,Fragai, Marco,Luchinat, Claudio,Mordini, Alessandro
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supporting information
p. 565 - 569
(2013/07/26)
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- Synthesis of silica bromide as heterogeneous reagent and its application to conversion of alcohols to alkyl bromides
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Silica bromide as heterogeneous reagent is prepared from the reaction of silica gel with PBr3 as a nonhydroscopic, filterable, cheap, and stable yellowish powder that can be stored for months. The results show that the silica bromide is a suitable and efficient reagent for conversion of alcohols to alkyl bromides under mild conditions at room temperature. The easy availability of this reagent makes this simple procedure attractive and a practical alternative to the existing methods.
- Mohanazadeh, Farajollah,Sedrpoushan, Alireza,Zolfigol, Mohammad A.,Veisi, Hojat
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p. 598 - 603,6
(2012/12/11)
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- Preparation of ionic liquid-based vilsmier reagent from novel multi-purpose dimethyl formamide-like ionic liquid and its application
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In continuation of research to explore the applied potential of DMF-like ionic liquid, the ionic liquid version of N,N-dimethyliminiumchloride (Vilsmier reagent) has been synthesized from DMF-like ionic liquid and tested effectively for its capacity to achieve more useful organic transformations. The results show that DMF-like ionic liquid is world's first task specific ionic liquid which has catalyzed numerous diverse type of reaction and is multipurpose in its application. Thus a new term for this DMF-like ionic liquid has been coined that is DMF-like "multipurpose" ionic liquid. Copyright
- Hullio, Ahmed Ali,Mastoi
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scheme or table
p. 1647 - 1657
(2012/09/21)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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supporting information
p. 2692 - 2698,7
(2012/12/12)
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- A facile and green protocol for nucleophilic substitution reactions of sulfonate esters by recyclable ionic liquids [bmim][X]
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Ionic liquids [bmim][X] (X = Cl, Br, I, OAc, SCN) are highly efficient reagents for nucleophilic substitution reactions of sulfonate esters derived from primary and secondary alcohols. The counter anions (X-) of the ionic liquids, [bmim][X], effectively replace the sufonates affording the corresponding substitution products such as alkyl halides, acetates, and thiocyanides in excellent yields. The newly developed protocol is very environmentally attractive because the reactions use stoichiometric amounts of ionic liquids as sole reagents in most cases and do not require additional solvents, any other activating reagents, non-conventional equipment, or special precautions. Moreover, these ionic liquids can be readily recycled without loss of reactivity, making the whole process greener. Georg Thieme Verlag KG Stuttgart · New York.
- Liu, Yajun,Xu, Yongnan,Jung, Sun Ho,Chae, Junghyun
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supporting information
p. 2692 - 2698
(2013/01/15)
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- Efficient procedures to prepare primary and secondary alkyl halides from alkanols via the corresponding sulfonates under mild conditions
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The study presented herein shows that sulfonate/halide exchange can be advantageously performed in THF to avoid several side reactions such as elimination and epimerization when the reaction is performed from a chiral alkyl sulfonate or a substrate having a C-H acidic chiral center. The main limitation of this procedure was found to be the conversion of secondary alkyl sulfonates to alkyl chlorides. In this case, the addition of a catalytic amount of manganese chloride clearly accelerates the rate and the efficiency of the reaction. Copyright
- Cahiez, Gerard,Gager, Olivier,Moyeux, Alban,Delacroix, Thomas
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supporting information; experimental part
p. 1519 - 1528
(2012/07/03)
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- In situ phosphine oxide reduction: A catalytic appel reaction
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Several important reactions in organic chemistry thrive on stoichiometric formation of phosphine oxides from phosphines. To avoid the resulting burden of waste and purification, cyclic phosphine oxides were evaluated for new catalytic reactions based on in situ regeneration. First, the ease of silane-mediated reduction of a range of cyclic phosphine oxides was explored. In addition, the compatibility of silanes with electrophilic halogen donors was determined for application in a catalytic Appel reaction based on in situ reduction of dibenzophosphole oxide. Under optimized conditions, alcohols were effectively converted to bromides or chlorides, thereby showing the relevance of new catalyst development and paving the way for broader application of organophosphorus catalysis by in situ reduction protocols. Copyright
- Van Kalkeren, Henri A.,Leenders, Stefan H. A. M.,Hommersom, C. Rianne A.,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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supporting information; experimental part
p. 11290 - 11295
(2011/10/19)
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- Synthesis of linearly and angularly fused indane-based constrained α-amino acid derivatives
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The benzocyclobutene-based α-amino acid derivative, ethyl 5-acetamido-2,4,5,6-tetrahydro-1H-cyclobuta[f]indene-5-carboxylate is synthesized via coupling of a benzocyclobutene-derived dibromide with ethyl isocyanoacetate as the key step, followed by hydrolysis and subsequent acetylation. This methodology is generalized in order to prepare various linearly and angularly fused indane-based α-amino acid derivatives. Georg Thieme Verlag Stuttgart - New York.
- Kotha, Sambasivarao,Krishna, Nimita Gopal,Misra, Shilpi,Khedkar, Priti
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scheme or table
p. 2945 - 2950
(2011/10/19)
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- SUBSTITUTED 4-AMINO-PIPERIDINES
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The present invention relates to new substituted 4-amino-piperidine opioid receptor modulators, pharmaceutical compositions thereof, and methods of use thereof
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Page/Page column 19
(2010/02/17)
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- Effect of structure of nucleophile and substrate on the quaternization of heterocyclic amines
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The influence of the nature of the quaternizing agent and substrate on the quaternization of heterocyclic amines, derivatives of pyridine, ss-picoline, nicotinamide, pyridoxine, was studied. The synthesized compounds were characterized by IR spectroscopy and elemental analysis. The conclusions were made about the effect of the structure of nucleophile and substrate on the process of quaternization reaction. Pleiades Publishing, Ltd., 2010.
- Zhuravlev,Verolainen,Voronchikhina
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experimental part
p. 1025 - 1028
(2011/01/11)
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- H3PW12O40-[bmim][FeCl4]: A novel and green catalyst-medium system for microwave-promoted selective interconversion of alkoxymethyl ethers into their corresponding nitriles, bromides and iodides
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In the present work, the catalytic activity of 12-tungstophosphoric acid immobilized on [bmim][FeCl4] ionic liquid as a highly efficient and eco-friendly catalytic system for rapid and chemoselective direct conversion of MOM- or EOM-ethers into their corresponding nitriles, bromides and iodides under microwave irradiation is reported. In these reactions, the products are obtained in high yields. The catalyst exhibited remarkable reactivity and was reused several times.
- Mohammadpoor-Baltork, Iraj,Moghadam, Majid,Tangestaninejad, Shahram,Mirkhani, Valiolah,Mirjafari, Arsalan
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experimental part
p. 1468 - 1473
(2011/10/09)
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- Microwave-promoted, one-pot conversion of alkoxymethylated protected alcohols into their corresponding nitriles, bromides, and iodides using [bmim][InCl4] as a green catalyst
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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
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supporting information; experimental part
p. 3274 - 3276
(2010/07/18)
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- Novel preparation of ion-supported triphenylphosphines and their synthetic utility
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Novel ion-supported Ph3P compounds, 4-(diphenylphosphino)- benzyltrimethylammonium bromide (A) and N-methyl-N-[4-(diphenylphosphino) -benzyl]pyrrolidinium bromide (B), were prepared. Because of their stability in air, ion-supported Ph3P A and B could be used for the halogenation of alcohols, the esterification of carboxylic acid with the Mitsunobu reaction, the Mizoroki-Heck reaction, and the Sonogashira reaction. The advantages of using these ion-supported Ph3P A and B are the simple isolation of the products by ether extraction due to their poor solubility in ether, and the easy recovery of the co-product, ion-supported Ph3PO, by filtration in high yields (>90%), which could be regenerated and reused for the same reactions, in the halogenation of alcohols and the esterification of carboxylic acid with the Mitsunobu reaction. On the other hand, ionic liquid reaction media containing Pd(OAc)2 or PdCl2 and ion-supported Ph3P A or B as catalysts could be reused for the same Mizoroki-Heck reaction and the Sonogashira reaction maintaining high yields, using iodotoluene with methyl acrylate and phenylacetylene, respectively.
- Imura, Yumi,Shimojuh, Naoya,Kawano, Yuhta,Togo, Hideo
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scheme or table
p. 3421 - 3426
(2010/06/19)
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- Hexabromoacetone and ethyl tribromoacetate: a highly efficient reagent for bromination of alcohol
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A new and efficient method for the bromination of alcohols utilizing Br3CCOCBr3/PPh3 and Br3CCO2Et/PPh3 is described. Various alcohols can be converted smoothly into their corresponding alkyl bromides in high yields under mild conditions with short reaction times. Based upon 1H NMR studies using competitive reactions between selected brominating agents and Cl3CCN, Br3CCOCBr3 displays the highest reactivity approximately nine times that of CBr4.
- Tongkate, Pratoomrat,Pluempanupat, Wanchai,Chavasiri, Warinthorn
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p. 1146 - 1148
(2008/09/18)
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- Regioselective photochemical and microwave mediated monobromination of aromatic compounds using 2,4,4,6-tetrabromo-2,5-cyclohexadienone
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Bromination of different aromatic substrates have been described using 2,4,4,6-tetrabromo-2,5-cyclohexadienone in conjunction with microwave and ultraviolet radiations. Important features of the work include high regioselectivity obtained in very short to moderate reaction time, atom economy, and recyclability of the reagent. Copyright Taylor & Francis Group, LLC.
- Gupta, Neeraj,Kad, Goverdhan L.,Singh, Vasundhara,Singh, Jasvinder
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p. 3421 - 3428
(2008/02/12)
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- 4-Aminophenyldiphenylphosphinite (APDPP), a new heterogeneous and acid scavenger phosphinite - Conversion of alcohols, trimethylsilyl, and tetrahydropyranyl ethers to alkyl halides with halogens or N-halosuccinimides
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A new heterogeneous phosphinite, 4-aminophenyldiphenylphosphinite (APDPP), is prepared and used for the efficient conversion of alcohols, trimethylsilyl ethers, and tetrahydropyranyl ethers to their corresponding bromides, iodides, and chlorides in the presence of molecular halogens or N-halosuccinimides. The amino group in this phosphinite acts as an acid scavenger and removes the produced acid. A simple filtration easily removes the phosphinate by-product.
- Iranpoor, Nasser,Firouzabadi, Habib,Gholinejad, Mohammad
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p. 1006 - 1012
(2007/10/03)
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- Facile conversion of alcohols into their bromides and iodides by N-bromo and N-iodosaccharins/triphenylphosphine under neutral conditions
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N-Bromo and N-iodosaccharins in the presence of triphenylphosphine convert alcohols into the corresponding bromides and iodides in good to excellent yields at room temperature under neutral conditions.
- Firouzabadi, Habib,Iranpoor, Nasser,Ebrahimzadeh, Farzaneh
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p. 1771 - 1775
(2007/10/03)
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- Silicaphosphine (Silphos): A filterable reagent for the conversion of alcohols and thiols to alkyl bromides and iodides
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Silicaphosphine (Silphos), [P(Cl)3-n(SiO2) n], as a new heterogeneous reagent is introduced. This reagent converts alcohols and thiols to their corresponding bromides and iodides in the presence of X2 (X=Br, I) in refluxing CH3CN in high to quantitative yields. Use of Silphos provides a highly practical method for the easy separation of the Silphos oxide byproduct by a simple filtration.
- Iranpoor, Nasser,Firouzabadi, Habib,Jamalian, Arezu,Kazemi, Foad
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p. 5699 - 5704
(2007/10/03)
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- Method for producing alkane or alkene compound
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[PROBLEM TO BE SOLVED]: To provide a method for producing alkane or alkene compounds by reduction of carbon-carbon multiple bond. [SOLUTION]: The method for producing alkane or alkene compounds shown by the general formula (5)-(7) [wherein, R1, R2, R3, R4, R5, and R6 are optionally different and hydrogen etc. independently respectively] characterized by reacting either kind or these mixtures among alkene or alkyne compounds shown by general formula (1) or (2) [wherein, R1-R6 are the same as formula (5)-(7)] in the presence of at least one kind selected from groups of bromic acid and hydrogen peroxide shown by general formula (3) (wherein, M is hydrogen or metal atom; m is integer of 1-3), hydrazine compoun shown by general formula (4) [wherein, n is integer of equal to or more than 0], and acid. [EFFECT]: Alkane or alkene compounds can be produced handily without hydrogenation equipment.
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Page/Page column 16
(2008/06/13)
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- Direct Radical Polymerization of 4-Styryldiphenylphosphine: Preparation of Cross-Linked and Non-Cross-Linked Triphenylphosphine-Containing Polystyrene Polymers
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We report herein a simple synthesis of 4-styryldiphenylphosphine and the radical copolymerization of it with styrene, both with and without a cross-linker, to directly form cross-linked and non-cross-linked polystyrene supported triphenylphosphine in which the level of phosphine incorporation can be easily and accurately controlled. The utility of these polymers is demonstrated by their use in Mitsunobu and alcohol bromination reactions.
- Choi, Matthew Kwok Wai,He, Helen Song,Toy, Patrick H.
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p. 9831 - 9834
(2007/10/03)
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- A simple and efficient iodination of alcohols on polymer-supported triphenylphosphine
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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
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p. 190 - 191
(2013/09/06)
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