- On the toxicity of phenols to fast growing cells. A QSAR model for a radical-based toxicity
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The cytotoxicities of a series of simple phenols as well as estrogenic phenols such as octyl and nonyl phenols, Bisphenol A, diethylstilbestrol, estradiol, estriol, equilin and equilenin were studied in a fast growing murine leukemia cell line. The use of calculated homolytic bond dissociation energies (BDE) as the electronic parameter led to the development of a Quantitative Structure-Activity Relationship model with superior results; one which established the importance of relatively low BDE values in enhancing toxicity to rapidly multiplying cells. The correlation equation that emerged is as follows: log 1/C= -0.19BDE + 0.21 log P + 3.11. It suggests that toxicity is closely related to mostly homolytic cleavage of the phenolic O-H bond and overall hydrophobicity of the phenol.
- Selassie, Cynthia D.,Shusterman, Alan J.,Kapur, Sanjay,Verma, Rajeshwar P.,Zhang, Litai,Hansch, Corwin
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Read Online
- Investigating the microwave-accelerated Claisen rearrangement of allyl aryl ethers: Scope of the catalysts, solvents, temperatures, and substrates
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The microwave-accelerated Claisen rearrangement of allyl aryl ethers was investigated, in order to gain insight into the scope of the catalysts, solvents, temperatures, and substrates. Among the catalysts examined, phosphomolybdic acid (PMA) was found to greatly accelerate the reaction in NMP, at temperatures ranging from 220 to 300 °C. This method was found to be useful for preparing several intermediates previously reported in the literature using precious metal catalysts such as Au(I), Ag(I), and Pt(II). Additionally, substrates bearing bromo and nitro groups on the aryl portion required careful tailoring of the reaction conditions to avoid complex product profiles.
- Hui, Zi,Jiang, Songwei,Qi, Xiang,Ye, Xiang-Yang,Xie, Tian
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supporting information
(2020/05/18)
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- A Construction of α-Alkenyl Lactones via Reduction Radical Cascade Reaction of Allyl Alcohols and Acetylenic Acids
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An iron-catalyzed cascade reaction of radical reduction of allyl alcohols and acetylenic acids to construct polysubstituted α-alkenyl lactones has been developed. In this paper, various allyl alcohols can form allyl ester intermediates and are further transformed into alkyl radicals, which form products through intramolecular reflex-Michael addition. In addition, this method can be used to prepare spirocycloalkenyl lactones. Interestingly, this protocol can be used to synthesize the skeleton structure of natural products. Moreover, the product can be further transformed into a β-methylene tetrahydrofuran and tetrahydrofuran diene.
- Zhang, Hua,Zhang, Guo-Min,He, Shuai,Shi, Zhi-Chuan,Zhang, Xiao-Mei,Wang, Ji-Yu
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supporting information
p. 8337 - 8344
(2020/11/03)
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- Iron(III) Chloride/Phenylsilane-Mediated Cascade Reaction of Allyl Alcohols with Maleimides: Synthesis of Poly-Substituted γ-Butyrolactones
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A iron-catalyzed free radical cascade reaction of allyl alcohols with N-substituted maleimides for accessing poly-substituted γ-butyrolactones has been developed. In this protocol, various allyl alcohols can open N-substituted maleimide rings to form allyl ester intermediates, and the allyl ester intermediates can be converted into an allyl ester alkyl radicals and undergo intramolecular free radical addition cyclization to form a polysubstituted γ-butyrolactones. In this protocol, spiro γ-butyrolactone compounds can be also synthesized. Meanwhile, the strategy could be applied to further construct a fully substituted tetrahydrofuran. The reaction is not sensitive to oxygen or moisture and has been performed on gram-scale. (Figure presented.).
- Zhang, Hua,Zhan, Xiao-Yu,Chen, Xu-Ling,Tang, Lei,He, Shuai,Shi, Zhi-Chuan,Wang, Yu,Wang, Ji-Yu
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supporting information
p. 4919 - 4925
(2019/11/03)
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- Method for compounding benzofuran derivatives by adding C-O bonds into olefin molecules through non-metallic Lewis acid catalysis
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The invention provides a method for compounding benzofuran derivatives by adding C-O bonds into olefin molecules through non-metallic Lewis acid catalysis. The method includes step 1, subjecting raw materials, namely phenol derivatives, to three-step reactions to obtain olefin serving as a reaction substrate; step 2, adding non-metallic Lewis acid and methylbenzene into the reaction substrate obtained in the step 1, and obtaining the benzofuran derivatives after reaction. The method has the advantages that the non-metallic Lewis acid is taken as a catalyst during reaction, so that pollution ofresidual metal catalysts to products is avoided, and troubles in post-treatment are omitted.
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Paragraph 0026; 0028; 0030; 0031
(2018/10/02)
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- Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4-Dioxane
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A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.
- Hokamp, Tobias,Dewanji, Abhishek,Lübbesmeyer, Maximilian,Mück-Lichtenfeld, Christian,Würthwein, Ernst-Ulrich,Studer, Armido
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supporting information
p. 13275 - 13278
(2017/10/09)
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- Palladium-Catalyzed Tandem Oxidative Arylation/Olefination of Aromatic Tethered Alkenes/Alkynes
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We describe herein a palladium-catalyzed tandem oxidative arylation/olefination reaction of aromatic tethered alkenes/alkynes for the synthesis of dihydrobenzofurans and 2 H-chromene derivatives. This reaction features a 1,2-difunctionalization of C?C π-bond with two C?H bonds using O2as terminal oxidant at room temperature. The products obtained are valuable synthons and important scaffolds in biological agents and natural products.
- Gao, Yang,Gao, Yinglan,Wu, Wanqing,Jiang, Huanfeng,Yang, Xiaobo,Liu, Wenbo,Li, Chao-Jun
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supporting information
p. 793 - 797
(2017/02/05)
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- Development and Mechanistic Study of Quinoline-Directed Acyl C-O Bond Activation and Alkene Oxyacylation Reactions
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The intramolecular addition of both an alkoxy and acyl substituent across an alkene, oxyacylation of alkenes, using rhodium catalyzed C-O bond activation of an 8-quinolinyl ester is described. Our unsuccessful attempts at intramolecular carboacylation of ketones via C-C bond activation ultimately informed our choice to pursue and develop the intramolecular oxyacylation of alkenes via quinoline-directed C-O bond activation. We provide a full account of our catalyst discovery, substrate scope, and mechanistic experiments for quinoline-directed alkene oxyacylation.
- Hoang, Giang T.,Walsh, Dylan J.,McGarry, Kathryn A.,Anderson, Constance B.,Douglas, Christopher J.
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p. 2972 - 2983
(2017/03/23)
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- Diarylation of alkenes by a Cu-catalyzed migratory insertion/cross-coupling cascade
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A strategy for the catalytic diarylation of alkenes is presented. The method involves the migratory insertion of alkenes into an Ar-Cu complex to generate a new C(sp3)-Cu complex, which subsequently undergoes reaction with an aryl iodide to constitute a vicinal diarylation of an alkene. The method provides access to benzofuran- and indoline-containing products. Furthermore, highly diastereoselective examples are presented, allowing access to complex, stereochemically rich structures from simple alkene starting materials.
- You, Wei,Brown, M. Kevin
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p. 14730 - 14733
(2014/12/11)
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- Insertion of an Alkene into an ester: Intramolecular oxyacylation reaction of alkenes through acyl C-O bond activation
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Atom economy and esters: compatible now! The first catalytic insertion of a C-C bond into an acyl C-O bond was achieved using rhodium catalysts (see scheme). The products are β-alkoxy ketones with a fully substituted carbon center. Quinoline chelating groups were employed to stabilize the Rh-alkoxide intermediate.
- Hoang, Giang T.,Reddy, Venkata Jaganmohan,Nguyen, Huy H. K.,Douglas, Christopher J.
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supporting information; experimental part
p. 1882 - 1884
(2011/04/16)
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- Pd-Catalyzed intramolecular oxyalkynylation of alkenes with hypervalent iodine
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(Figure presented) The first example of intramolecular oxyalkynylation of nonactivated alkenes using oxidative Pd chemistry is reported. Both phenol and aromatic or aliphatic acid derivatives could be used under operator-friendly conditions (room temperature, technical solvents, under air). The discovery of the superiority of benzlodoxolone-derlved hypervalent iodine reagent 3d as an alkyne transfer reagent further expands the rapidly increasing utility of hypervalent iodine reagents in catalysis and is expected to have important implications for other similar processes.
- Nicolal, Stefano,Erard, Stephane,Gonzalez, Davinla Fernandez,Waser, Jerome
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supporting information; experimental part
p. 384 - 387
(2010/03/04)
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- Exploring SmBr2-, SmI2-, and YbI2-mediated reactions assisted by microwave irradiation
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The use of microwave heating in lanthanide(II) halide (LnX2 = SmBr2, SmI2, and YbI2) mediated reduction and coupling reactions has been investigated for a variety of functional groups including α,β-unsaturated esters, aldehydes, ketones, imines, and alkyl halides. Good to quantitative transformations were obtained within a few minutes without the addition of any co-solvents, such as hexamethyl phosphoramide (HMPA). The redox potential of YbI2 in tetrahydrofuran (THF) has been determined as -1.02± 0.05 V (versus Ag/AgNO3) by cyclic voltammetry. A large selectivity difference in various reactions was observed depending on the redox potential of the LnX2 reagent. The more powerful reductant, SmBr2, afforded mainly pinacol-coupling products of ketones whereas the weaker reductant YbI2 afforded mainly reduction products. The results indicate that the reducing power of LnX 2 has a large impact on not only the pinacol coupling/reduction product ratio of ketones but also on other substrates in which there are competing coupling and reduction reactions. The use of in situ generated LnX2 has also been explored and proven useful in many of these reactions.
- Dahlen, Anders,Prasad, Edamana,Flowers II, Robert A.,Hilmersson, Goeran
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p. 3279 - 3284
(2007/10/03)
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- Diastereoselective intramolecular SmI2-H2O-amine mediated couplings
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The effectiveness of SmI2-H2O-amine mixture for intramolecular couplings was discussed. Diastereoselectivities in the coupling of O-cyclohexanyliodophenol derivatives were provided into heterocycles. The amount of coupled product improved significantly as SmI2, the substrate and amine were premixed followed by a gradual addition of water.
- Dahlen, Anders,Petersson, Annika,Hilmersson, Goeran
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p. 2423 - 2426
(2007/10/03)
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- SmI2/water/amine mediates cleavage of allyl ether protected alcohols: application in carbohydrate synthesis and mechanistic considerations.
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[reaction: see text]. SmI2/H2O/amine provides selective cleavage of unsubstituted allyl ethers in good to excellent yields. This method is therefore useful in deprotection of alcohols and carbohydrates.
- Dahlen, Anders,Sundgren, Andreas,Lahmann, Martina,Oscarson, Stefan,Hilmersson, Goeran
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p. 4085 - 4088
(2007/10/03)
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- Thermodynamic, spectroscopic, and density functional theory studies of allyl aryl and prop-1-enyl aryl ethers. Part 1. Thermodynamic data of isomerization
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A chemical equilibration study of the relative thermodynamic stabilities of seventy isomeric allyl aryl ethers (a) and (Z)-prop-1-enyl aryl ethers (b) in DMSO solution has been carried out. From the variation of the equilibrium constant with temperature the Gibbs energies, enthalpies, and entropies of isomerization at 298.15 K have been evaluated. Because of their low enthalpies, the (Z)-prop-1-enyl aryl ethers are strongly favored at equilibrium, the Gibbs energies of the a→b isomerization ranging from -12 to -23 kJ mol-1. The entropy contribution is negligible in most reactions, but occasionally small positive values less than +10 J K-1 mol-1 of the entropy of isomerization are found. The equilibration studies were also extended to involve two pairs of related isomeric ethers with a Me substituent on C(2) of the olefinic bond. The Me substituent was found to increase the relative thermodynamic stability of the allylic ethers by ca. 3.4 kJ mol-1.
- Taskinen, Esko
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p. 1824 - 1834
(2007/10/03)
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- Preparation of chiral building blocks for a highly convergent vitamin E synthesis. Systematic investigations on the enantioselectivity of the sharpless bishydroxylation
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The enantioselective bishydroxylation of protected 2-methylprop-2-enol 15 and 3-methylbut-3-en-1-ol 16 to give the corresponding diols 18 and 19, respectively, which can be transformed into building blocks for the synthesis of natural vitamin E, is described. It is shown that the enantioselectivity of the bishydroxylation reaction clearly depends on the type of protecting group and its distance from the alkene moiety, with 96% ee for 16a and 16f as the best and 8% ee for 15d as the lowest result.
- Tietze, Lutz F.,Goerlitzer, Jochen
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p. 873 - 878
(2007/10/03)
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- REACTIONS OF PHOSPHORUS PENTACHLORIDE WITH ALLYL ARYL ETHERS, SULFIDES, AND NAPHTHALENE DERIVATIVES
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Conditions for phosphorylation of allyl aryl and aryl methylallyl ethers and sulfides, as well as alkenyl- and alkoxynaphthalenes, have been developed.
- Anisimova, E. A.,Mitrasov, Yu. N.,Kormachev, V. V.
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p. 356 - 360
(2007/10/03)
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- ONE-POT SYNTHESES OF 2,3-DIHYDRO-2,2-DIMETHYLBENZOFURAN DERIVATIVES
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A tandem Claisen rearrangement-cyclization reaction of aryl methallyl ethers afforded the corresponding 2,3-dihydro-2,2-dimethylbenzofuran derivatives at -70 deg C with aluminium chloride.
- Kim, Kyoung Mahn,Kim, Hyoung Rae,Ryu, Eung K.
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p. 497 - 505
(2007/10/02)
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- Synthesis of allylic aryl ethers via palladium-catalyzed decarboxylation of allylic aryl carbonates
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Allylic aryl ethers are readily prepared in high yield by the palladium-catalyzed decarboxylation of allylic aryl carbonates.
- Larock,Lee
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p. 6315 - 6318
(2007/10/02)
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- "PALLADIUM COMPLEXES-KF / ALUMINA" CATALYSED EXCHANGE OF ALLYLIC GROUPS OF ESTERS WITH PHENOL
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In the presence of KF/alumina and catalytic amounts of palladium complexes, phenol reacts with allylic esters under mild conditions to give the corresponding allyl phenyl ethers.
- Muzart, J.,Genet, J.-P.,Denis, A.
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p. C23 - C28
(2007/10/02)
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- Rate Constants for the Cyclisation of Some Aryl Radicals bearing Unsaturated ortho-Substituents
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Rate constants and Arrhenius parameters have been determined for ring-closure of o-alkenyl- and o-alkenyloxy-aryl radicals, and for deuterium atom transfer from tributyltin deuteride.
- Abeywickrema, Anil N.,Beckwith, Athelstan L. J.
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p. 464 - 465
(2007/10/02)
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- Process for preparing 2,3-dihydro-2,2-dimethylbenzofuran-7-ol
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A process is described for preparing 2,3-dihydro-2,2-dimethylbenzofuran-7-ol (I), which is a useful intermediary in the preparation of Carbofuran, a known multi-functional insecticide. The process consists essentially of reacting the pyrocatechol and a methallylhalide in an inert organic solvent in the presence of a solid inorganic base and a suitable catalyst, to obtain o.methallyloxyphenol with high conversion and high selectivity; this product is thermally transposed to o.methallylpyrocatechol, which is finally cyclized to the product (I) by heterogeneous catalysis in the presence of solid acid catalysts. All stages of the process can be carried out in a single reaction medium, without separating intermediate products.
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- α-Adrenoreceptor Reagents. 2. Effects of Modification of the 1,4-Benzodioxan Ring System on α-Adrenoreceptor Activity
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Modification of the 1,4-benzodioxan ring present in RX 781094 (1) has not previously been considered.This paper describes a number of analogues of this ring system, including compounds in which one of the oxygen atoms has been replaced by a methylene group and also those in which the ring size has been changed to give, for example, furan and thiophene derivatives.The dihydroxybenzofuranylimidazoline compound 7 is the only analogue possesing presynaptic antagonist potency and selectivity comparable to that of 1.In view of this result, a number of derivatives was prepared to determine the structure-activity relationships within this series.Many derivatives, as well as the parent compound 7, were found to possess presynaptic α2-adrenoreceptor antagonist and postsynaptic α1-adrenoreceptor partial agonist properties.Two of the selective presynaptic antagonists,13 and 14, possess greater potency and selectivity than that possessed by 1.The 5-chloro derivative 25 is twice as potent as 1 after oral administration but only about half as potent when given intravenously.
- Chapleo, Christopher B.,Myers, Peter L.,Butler, Richard C. M.,Davis, John A.,Doxey, John C.,et al.
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p. 570 - 576
(2007/10/02)
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