- Silica-supported orthophosphoric acid (OPA/SiO2): preparation, characterization, and evaluation as green reusable catalyst for pinacolic rearrangement
-
In this paper, we report an easy-to-prepare, cost-effective, efficient, and reusable silica-supported orthophosphoric acid (OPA) catalyst for pinacolic rearrangement. The surface properties of this catalyst were successfully characterized with the help of 31P NMR, TGA, DSC, FT-IR, titration, and microscopy. OPA, hydrogen bonded on the surface, is actually the active species and the reaction seems to occur in the liquid phase embedded in the silica support. As a consequence, the extracting solvent should be chosen with cautious to guarantee the recyclability of the catalyst. As example, pinacol rearrangement reactions were successfully realized with this catalyst and OPA/SiO2 proved to be as efficient as homogeneous orthophosphoric acid to promote the reaction of pinacol derivatives. When using dichloromethane as extracting solvent, OPA/SiO2 can be reuse up to ten times without a significant loss of activity. After ten runs, no physical damage of the catalyst has been observed by microscopy proving its suitability for such application.
- Billamboz, Muriel,Banaszak, Estelle
-
-
Read Online
- TiCl4-Zn induced reductive acylation of ketones with acylsilanes
-
Acylsilanes were found to react with ketones in the presence of a low-valent titanium reagent generated from titanium(IV) chloride and zinc, giving the corresponding reductive acylated compounds.
- Sakurai, Hidehiro,Imamoto, Yuka,Hirao, Toshikazu
-
-
Read Online
- In vitro and in vivo activities of 2,3-diarylsubstituted quinoxaline derivatives against Leishmania amazonensis
-
Leishmaniasis is endemic in 98 countries and territories worldwide. The therapies available for leishmaniasis have serious side effects, thus prompting the search for new therapies. The present study investigated the antileishmanial activities of 2,3-diaryl-substituted quinoxaline derivatives against Leishmania amazonensis. The antiproliferative activities of 6,7-dichloro-2,3-diphenylquinoxaline (LSPN329) and 2,3-di-(4-methoxyphenyl)-quinoxaline (LSPN331) against promastigotes and intracellular amastigotes were assessed, and the cytotoxicities of LSPN329 and LSPN331 were determined. Morphological and ultrastructural alterations were examined by electron microscopy, and biochemical alterations, reflected by the mitochondrial membrane potential (ΔΨm), mitochondrial superoxide anion (O2.-) concentration, the intracellular ATP concentration, cell volume, the level of phosphatidylserine exposure on the cell membrane, cell membrane integrity, and lipid inclusions, were evaluated. In vivo antileishmanial activity was evaluated in a murine cutaneous leishmaniasis model. Compounds LSPN329 and LSPN331 showed significant selectivity for promastigotes and intracellular amastigotes and low cytotoxicity. In promastigotes, ultrastructural alterations were observed, including an increase in lipid inclusions, concentric membranes, and intense mitochondrial swelling, which were associated with hyperpolarization of ΔΨm, an increase in the O2.- concentration, decreased intracellular ATP levels, and a decrease in cell volume. Phosphatidylserine exposure and DNA fragmentation were not observed. The cellular membrane remained intact after treatment. Thus, the multifactorial response that was responsible for the cellular collapse of promastigotes was based on intense mitochondrial alterations. BALB/c mice treated with LSPN329 or LSPN331 showed a significant decrease in lesion thickness in the infected footpad. Therefore, the antileishmanial activity and mitochondrial mechanism of action of LSPN329 and LSPN331 and the decrease in lesion thickness in vivo brought about by LSPN329 and LSPN331 make them potential candidates for new drug development for the treatment of leishmaniasis.
- Kaplum, Vanessa,Cogo, Juliana,Sangi, Diego Pereira,Ueda-Nakamura, Tania,Corrêa, Arlene Gon?alves,Nakamura, Celso Vataru
-
-
Read Online
- An Oxidant- And Catalyst-Free Synthesis of Dibenzo[ a, c ]carbazoles via UV Light Irradiation of 2,3-Diphenyl-1 H -indoles
-
An efficient methodology for the synthesis of dibenzo[a,c]- carbazoles via annulation of 2,3-diphenyl-1H-indoles in EtOH under UV light irradiation (λO = 365 nm) along with hydrogen evolution is described. This method exhibits the advantages of mild reaction conditions, no requirement of any oxidants and catalysts, and release of hydrogen as the only byproduct. Notably, the mechanism investigation confirms that the trans-4b,8a-dihydro-9H-dibenzo[a,c]carbazole intermediate could convert into cis-4b,8a-dihydro-9H-dibenzo[a,c]carbazole, which relies on the nitrogen atom of the indole ring. This is followed by intramolecular dehydrogenation which yields the dibenzo[a,c]carbazoles. 2021. Thieme. All rights reserved.
- Hou, Rong,Kang, Yang,Liang, Yong,Min, Xiaoyan,Wang, Tao,Zhang, Zunting
-
-
- Continuous Flow Acylation of (Hetero)aryllithiums with Polyfunctional N,N-Dimethylamides and Tetramethylurea in Toluene
-
The continuous flow reaction of various aryl or heteroaryl bromides in toluene in the presence of THF (1.0 equiv) with sec-BuLi (1.1 equiv) provided at 25 °C within 40 sec the corresponding aryllithiums which were acylated with various functionalized N,N-
- Djukanovic, Dimitrije,Filipponi, Paolo,Heinz, Benjamin,Knochel, Paul,Mandrelli, Francesca,Martin, Benjamin,Mostarda, Serena
-
supporting information
p. 13977 - 13981
(2021/09/13)
-
- Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
-
Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
- Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
-
p. 11856 - 11863
(2021/08/16)
-
- Palladium-catalyzed secondary benzylic imidoylative reactions
-
Reported herein is a palladium-catalyzed secondary benzylic imidoylative Negishi reaction leveraging the sterically bulky aromatic isocyanides as the imine source. This method allows the facile access of alkyl-, (hetero)aryl-, and alkynylzinc reagents to afford various α-substituted phenylacetone products under mild acidic hydrolysis, which are ubiquitous motifs in many pharmaceuticals and biologically active compounds. The diastereoselective reduction of imine can be accomplished to provide the expedient conversion of secondary benzylic halide into α-substituted phenethylamine derivatives with high atom economy.
- Wang, Chenglong,Wu, Licheng,Xu, Wentao,He, Feng,Qu, Jingping,Chen, Yifeng
-
p. 6954 - 6959
(2020/09/15)
-
- Synthesis and antiseizure activity of (E)-1,2-diarylethylidenehydrazine carboximidamides against tonic-clonic seizures: an intracerebroventricular and electrophysiological study
-
A series of (E)-1,2-diarylethylidenehydrazine carboximidamides 2a–j were synthesized and characterized by NOESY experiment as anticonvulsant agents and their antiseizure activity was evaluated by intracerebroventricular administration of compounds. Most of the compounds had significant protection against tonic-clonic seizures and 2a was found to be as equipotent as carbamazepine in seizures control. In order to find their anticonvulsant mechanism of action, 2a was subjected to further electrophysiological studies using patch-clamp technique. The results confirmed that this compound is neither a voltage-gated sodium channel blocker nor a NMDA/AMPA antagonist. Although 2a did not show any direct GABA agonistic activity, it could decrease EPSP and increase IPSP frequency without any change in amplitude. Finally, the results indicated most likely a presynaptic GABA-mediated mechanism of 2a for its antiseizure activity such as inhibition of the GABA-T which was validated by molecular docking.
- Firouzjaei, Fariba Abedi,Heidarli, Elmira,Ravan, Shabnam,Hosseini, Sayed Masoud,Naderi, Nima,Almasyan, Kiarash,Sarvary, Afshin,Irannejad, Hamid
-
p. 1520 - 1535
(2020/06/17)
-
- Combined Photoredox and Carbene Catalysis for the Synthesis of Ketones from Carboxylic Acids
-
As a key element in the construction of complex organic scaffolds, the formation of C?C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single-electron chemistry have enabled new methods for the formation of various C?C bonds. Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N-heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late-stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies.
- Betori, Rick C.,Davies, Anna V.,Fitzpatrick, Keegan P.,Scheidt, Karl A.
-
supporting information
p. 9143 - 9148
(2020/03/30)
-
- Diazaphosphinyl radical-catalyzed deoxygenation of α-carboxy ketones: A new protocol for chemo-selective C-O bond scission: Via mechanism regulation
-
C-O bond cleavage is often a key process in defunctionalization of organic compounds as well as in degradation of natural polymers. However, it seldom occurs regioselectively for different types of C-O bonds under metal-free mild conditions. Here we report a facile chemo-selective cleavage of the α-C-O bonds in α-carboxy ketones by commercially available pinacolborane under the catalysis of diazaphosphinane based on a mechanism switch strategy. This new reaction features high efficiency, low cost and good group-tolerance, and is also amenable to catalytic deprotection of desyl-protected carboxylic acids and amino acids. Mechanistic studies indicated an electron-transfer-initiated radical process, underlining two crucial steps: (1) the initiator azodiisobutyronitrile switches originally hydridic reduction to kinetically more accessible electron reduction; and (2) the catalytic phosphorus species upconverts weakly reducing pinacolborane into strongly reducing diazaphosphinane. This journal is
- Cheng, Jin-Pei,Yang, Jin-Dong,Zhang, Jingjing
-
p. 8476 - 8481
(2020/09/07)
-
- Method for preparing diphenylethanone from benzyl alcohol through photocatalytic one-step method
-
The present invention relates to a method for preparing diphenylethanone from benzyl alcohol through a photocatalytic one-step method. According to the method, diphenylethanone is directly prepared byusing inexpensive benzyl alcohol as a raw material under the action of a solid photocatalyst; and the reaction process comprises: mixing benzyl alcohol, a catalyst and an acetonitrile solvent are mixed, placing in a pressure container, replacing with an inert gas, and carrying out illumination stirring at a room temperature, wherein the reaction time is more than 1 h, the catalyst is easily separated from the reaction system after the reaction and can be recycled multiple times, and the separation yield of diphenylethanone is up to 81%.
- -
-
Paragraph 0035; 0036
(2018/09/13)
-
- Hydrogen bond donor solvents enabled metal and halogen-free Friedel–Crafts acylations with virtually no waste stream
-
We have developed a metal and halogen-free Friedel–Crafts acylation protocol with virtually no waste stream generation. We propose a hydrogen bonding donor solvent will form a hydrogen bonding network and may provide significant rate enhancement for Friedel–Crafts reactions. Trifluoroacetic acid is one of the strongest H-bond donor solvents, which is also volatile and can be easily recovered by distillation without need for reaction workup. Our protocol is a ‘green’ Friedel–Crafts acylation process: 1) the catalyst can be recovered and reused; 2) using halogen free starting material (carboxylic acids anhydride or carboxylic acids); 3) no need for aqueous reaction work-up; 4) minimum or no waste steam generation.
- Liu, Guangchang,Xu, Bo
-
supporting information
p. 869 - 872
(2018/02/09)
-
- Nickel-Catalyzed Transformation of Aryl 2-Pyridyl Ethers via Cleavage of the Carbon-Oxygen Bond: Synthesis of Mono-α-arylated Ketones
-
The nickel/IPr-catalyzed reaction of aryl 2-pyridyl ethers with propiophenone and acetophenone derivatives via C-OPy bond cleavage is performed in the presence of t -BuOLi to give mono-α-arylated ketones in moderate yields. The method is suitable for electron-rich and electron-poor ethers as well as heteroaryl ethers and tolerates a range of active functional groups.
- Li, Jing,Wang, Zhong-Xia
-
p. 3217 - 3223
(2018/06/08)
-
- Vanadium-Catalyzed Oxidative C(CO)-C(CO) Bond Cleavage for C-N Bond Formation: One-Pot Domino Transformation of 1,2-Diketones and Amidines into Imides and Amides
-
A novel vanadium-catalyzed one-pot domino reaction of 1,2-diketones with amidines has been identified that enables their transformation into imides and amides. The reaction proceeds by dual acylation of amidines via oxidative C(CO)-C(CO) bond cleavage of 1,2-diketones to afford N,N′-diaroyl-N-arylbenzamidine intermediates. In the reaction, these intermediates are easily hydrolyzed into imides and amides through vanadium catalysis. This method provides a practical, simple, and mild synthetic approach to access a variety of imides as well as amides in high yields. Moreover, one-step construction of imide and amide bonds with a long-chain alkyl group is an attractive feature of this protocol.
- Digwal, Chander Singh,Yadav, Upasana,Ramya, P. V. Sri,Sana, Sravani,Swain, Baijayantimala,Kamal, Ahmed
-
p. 7332 - 7345
(2017/07/26)
-
- Synthesis of 2-Benzylphenyl Ketones by Aryne Insertion into Unactivated C-C Bonds
-
A transition-metal-free procedure to access to functionalized 2-benzylphenyl ketones is described by direct insertion of arynes into benzylic C-C bonds. This reaction was promoted by cesium fluoride at room temperature, allowing the products to form in high selectivity and achieve good functional group tolerance.
- Rao, Bin,Tang, Jinghua,Zeng, Xiaoming
-
supporting information
p. 1678 - 1681
(2016/04/26)
-
- Facile Access to Multiaryl-1H-pyrrol-2(3H)-ones by Copper/TEMPO-Mediated Cascade Annulation of Diarylethanones with Primary Amines and Mechanistic Insight
-
A straightforward approach to an array of multiaryl-1H-pyrrol-2(3H)-ones featuring an α-diarylated all-carbon quaternary center was developed by using diarylethanones and primary amines as the raw materials. A complete mechanism involving a CuO/TEMPO-mediated multistep cascade process with an inherent delicate balance of substituent electronic effect is proposed. Moreover, this class of multiaryl β,γ-unsaturated γ-lactams demonstrates an intriguing aggregation-induced emission effect valuable for potential application in developing luminescent materials.
- Wang, Xing,Zhang, Chen-Yang,Tu, Hai-Yang,Zhang, Ai-Dong
-
supporting information
p. 5243 - 5247
(2016/11/13)
-
- Molecular design, synthesis and evaluation of 2,3-diarylquinoxalines as estrogen receptor ligands
-
Selective Estrogen Receptor Modulators (SERMs) are characteristically capable of being antagonist and agonist of estrogen receptors and, therefore, they can inhibit or stimulate estrogen production in different tissues. Aiming to contribute to the identification of new synthetic SERMs candidates, the basic skeletons of raloxifene and tamoxifene were used as model. Here of, a set of 2,3-diaryl-quinoxalines having 2-(piperidin-1-yl)ethanol in the side chain have been synthesized and evaluated against human mammary carcinoma cells estrogen dependent (MCF-7), as well as in recombinant yeast assays (RYA) expressing estrogen receptor. Compound LSPN332 showed 40% inhibition of MCF-7 and EC50=290.6 μM in RYA. The efficient synthesis of 2,3-diarylquinoxalines represents an excellent opportunity to identify new SERMs, and should therefore be of interest to the medicinal chemistry community.
- Sangi, Diego P.,Cominetti, Márcia R.,Becceneri, Amanda B.,Resende, Flavia A.,Varanda, Eliana A.,Montanari, Carlos A.,Paix?o, Marcio W.,Corrêa, Arlene G.
-
p. 736 - 746
(2015/12/01)
-
- Synthesis of substituted phenanthrofurans
-
A three-step protocol toward phenanthrofurans 1 starting with deoxybenzoins 3 is developed with moderate to good yield. A facile process is carried out for the (1) α-propargylation of 3 with NaH and propargyl bromide 2 in refluxing THF, (2) Bi(OTf)3-mediated cycloisomerization of γ-ynones 4 with 4 ? molecular sieves in MeNO2 at rt, and (3) photolytic Scholl annulation of 2,3-diarylfurans 5 with I2 in EtOAc at rt. The key structures of 1 are confirmed by X-ray crystallographic analysis.
- Chan, Chieh-Kai,Chen, Yi-Chia,Chen, Yeh-Long,Chang, Meng-Yang
-
p. 9187 - 9195
(2015/11/27)
-
- Visible Light Mediated Reductive Cleavage of C-O Bonds Accessing α-Substituted Aryl Ketones
-
C-O σ-bonds in multifaceted benzoin derivatives can be effectively cleaved as acetates using catalytic amounts of [Ru(bpy)3]Cl2 as photoredox catalyst in combination with Hantzsch ester and triethylamine as a sacrificial electron donor. This mild and operationally simple method is applicable to a great variety of substrates. Homo- and cross-benzoins, which are easily accessed by NHC (N-heterocyclic carbene) catalysis, with both electron-withdrawing and electron-donating substituents, including aryl halogenides, can be employed. The deoxygenated counterparts are isolated in good to excellent yields. These broadly accessible, α-substituted (nonsymmetric) aryl ketones are versatilely applicable for further transformations as illustrated by the syntheses of 2-arylbenzofurans.
- Speckmeier, Elisabeth,Padié, Clément,Zeitler, Kirsten
-
p. 4818 - 4821
(2015/10/12)
-
- HETEROCYCLIC COMPOUNDS FOR THE INHIBITION OF PASK
-
Disclosed herein are new heterocyclic compounds of Formula IIa: and compositions thereof, and their application as pharmaceuticals for the treatment of disease. Methods of inhibiting PAS Kinase (PASK) activity in a human or animal subject are also provided for the treatment of diseases such as diabetes mellitus.
- -
-
Paragraph 0235; 0345; 0346; 0363; 0364
(2014/05/20)
-
- Synthesis, cytotoxic evaluation, and molecular docking study of 4,5-diaryl-thiazole-2-thione analogs of combretastatin A-4 as microtubule-binding agents
-
A series of combretastatin A-4 analogs in which cis-olefinic bond replaced by thiazole ring were prepared by reaction of α-bromo-1,2-(p-substituted) diaryl-1-ethanones and dithiocarbamate derivatives. The cytotoxicity of these compounds was determined against three cancer cell lines (HT-29), (MCF-7), (AGS) as well as fibroblastic cell line (NIH-3T3) using MTT assay. Inhibition of tubulin polymerization for some potent compounds was evaluated. These biological studies proved that 6j and 6o were the most potent compounds in this series. Furthermore 2-(methylthio)-substituted compounds show moderate or no activity. Docking studies involving 6j and 6o demonstrated that this analogs could be successfully docked in the colchicine binding site of α,β-tubulin.
- Salehi, Marjan,Ostad, Seyed Nasser,Riazi, Gholam Hossein,Assadieskandar, Amir,Cheraghi-Shavi, Tayebeh,Shafiee, Abbas,Amini, Mohsen
-
p. 1465 - 1473
(2014/03/21)
-
- General and mild Ni0-catalyzed α-arylation of ketones using aryl chlorides
-
A general methodology for the α-arylation of ketones using a nickel catalyst has been developed. The new well-defined [Ni(IPr)(cin)Cl] (1c) pre-catalyst showed great efficiency for this transformation, allowing the coupling of a wide range of ketones, including acetophenone derivatives, with various functionalised aryl chlorides. This cinnamyl-based Ni-N-heterocyclic carbene (NHC) complex has demonstrated a different behaviour to previously reported NHC-Ni catalysts. Preliminary mechanistic studies suggest a Ni0/NiII catalytic cycle to be at play.
- Fernndez-Salas, Jos A.,Marelli, Enrico,Cordes, David B.,Slawin, Alexandra M.Z.,Nolan, Steven P.
-
supporting information
p. 3906 - 3909
(2015/10/19)
-
- Influence of chlorine or fluorine substitution on the estrogenic properties of 1-alkyl-2,3,5-tris(4-hydroxyphenyl)-1H-pyrroles
-
In continuation of our previous work, several 1-alkyl-2,3,5-tris(4- hydroxyphenyl)aryl-1H-pyrroles with chlorine or fluorine substituents in the aryl residues were synthesized and tested for estrogen receptor (ER) binding at isolated ERα/ERβ receptors (HAP assay) and in transactivation assays using ERα-positive MCF-7/2a as well as U2-OS/ERα and U2-OS/ERβ cells. In the competition experiment at ERα the compounds displayed very high relative binding affinities of up to 37% (determined for 8m) but with restricted subtype selectivity (e.g., ERα/ERβ (8m) = 9). The highest estrogenic potency in ERα-positive MCF-7/2a cells was determined for 2,3,5-tris(2-fluoro-4-hydroxyphenyl)-1-propyl-1H-pyrrole 8m (EC50 = 23 nM), while in U2-OS/ERα cells 2-(2-fluoro-4-hydroxyphenyl)-3,5-bis(4- hydroxyphenyl)-1-propyl-1H-pyrrole 8b (EC50 = 0.12 nM) was the most potent agonist, only 30-fold less active than estradiol (E2, EC50 = 0.004 nM). In U2-OS/ERβ cells for all pyrroles no transactivation could be observed, which indicates that they are selective ERα agonists in cellular systems.
- Sch?fer, Anja,Wellner, Anja,Strauss, Martin,Sch?fer, Andreas,Wolber, Gerhard,Gust, Ronald
-
supporting information
p. 9607 - 9618
(2013/01/16)
-
- HETEROCYCLIC COMPOUNDS FOR THE INHIBITION OF PASK
-
Disclosed herein are new heterocyclic compounds and compositions and their application as pharmaceuticals for the treatment of disease. Methods of inhibiting PAS Kinase (PASK) activity in a human or animal subject are also provided for the treatment of diseases such as diabetes mellitus.
- -
-
Page/Page column 40-41
(2012/09/11)
-
- Synthesis, spectral studies and biological evaluation of a novel series of 2-substituted-5,6-diarylsubstituted imidazo(2,1-b)-1,3, 4-thiadiazole derivatives as possible anti-tubercular agents
-
A novel series of 18 analogs of 2-substituted-5,6- diarylsubstituted imidazo(2,1-b)-1,3,4-thiadiazole 6a-r have been synthesized by the reaction of 2-amino-5-substituted- 1,3,4-thiadiazoles 5a-d and an appropriately substituted a-bromo-1,2-(p-substituted)diaryl-1-ethanones 4a-e. Structures of these compounds were established by physiochemical, elemental analysis and spectral data. All the title compounds were tested for their in-vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv using Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in lg/ml. Among synthesized compounds, compound 6h (MIC = 1.25 μg/ml) exhibited excellent anti-tubercular activity with respect to other synthesized compounds and reference drugs. Compounds 6c, 6f, and6g have also displayed an encouraging anti-tubercular activity profile. Further, some title compounds were also assessed for their cytotoxic activity (IC 50) against in a mammalian Vero cell line using MTT assay. The results reveal that these compounds exhibit anti-tubercular activity at non-cytotoxic concentrations. Springer Science+Business Media, LLC 2011.
- Palkar, Mahesh B.,Noolvi, Malleshappa N.,Maddi, Veeresh S.,Ghatole, Mangala,Nargund, Laxmivenkat G.
-
experimental part
p. 1313 - 1321
(2012/08/07)
-
- N-heterocyclic carbene adducts of cyclopalladated ferrocenylpyridazine: Synthesis, structural characterization, and application in α-arylation of ketones with aryl chlorides
-
A new ferrocene-based ligand 3-chloro-6-pyridazinylferrocene 1 and its N-heterocyclic carbene adducts 2-3 were synthesized and characterized by 1H NMR and IR spectroscopy, ESI-MS, and elemental analysis. Additionally, detailed structures of complexes 2-3 have been determined by single-crystal X-ray analysis. Complex 3 exhibited high catalytic activity for α-arylation of ketones with aryl chlorides. Typically, using 1mol% catalyst in the presence of 1.5 equivalents of tBuOK as base in dioxane at 100°C provided coupled products in good yields.
- Xu, Chen,Li, Hong-Mei,Wang, Zhi-Qiang,Fu, Wei-Jun,Zhang, Yu-Qing,Ji, Bao-Ming
-
experimental part
p. 366 - 370
(2012/07/16)
-
- Photochemically initiated oxidative carbon-carbon bond-cleavage reactivity in chlorodiketonate NiII complexes
-
Three mononuclear NiII complexes containing a 2-chloro-1,3-diketonate ligand and supported by the 6-Ph2TPA chelate, as well as analogues that lack the 2-chloro substituent on the β-diketonate ligand, have been prepared and characterized. Upon irradiation at 350 nm under aerobic conditions, complexes containing the 2-chloro-substituted ligands undergo reactions to generate products resulting from oxidative cleavage, α-cleavage, and radical-derived reactions involving the 2-chloro-1,3-diketonate ligand. Mechanistic studies suggest that the oxidative cleavage reactivity, which leads to the production of carboxylic acids, is a result of the formation of superoxide, which occurs through reaction of reduced nickel complexes with O2. The presence of the 2-chloro substituent was found to be a prerequisite for oxidative carbon-carbon bond-cleavage reactivity, as complexes lacking this functional group did not undergo these reactions following prolonged irradiation. The approach toward investigating the oxidative reactivity of metal β-diketonate species outlined herein has yielded results of relevance to the proposed mechanistic pathways of metalloenzyme-catalyzed β-diketonate oxidative cleavage reactions.
- Allpress, Caleb J.,Arif, Atta M.,Houghton, Dylan T.,Berreau, Lisa M.
-
supporting information; body text
p. 14962 - 14973
(2012/02/06)
-
- (N-Heterocyclic Carbene)-Pd-catalyzed anaerobic oxidation of secondary alcohols and domino oxidation-arylation reactions
-
The use of commercially available (SIPr)Pd(cinnamyl)Cl (SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene) as a precatalyst for the anaerobic oxidation of secondary alcohols is described. The use of this complex allows for a drastic reduction in the reaction times and catalyst loading when compared to the unsaturated counterpart. This catalytic system is compatible with the use of microwave dielectric heating, decreasing even further catalyst loading and reaction times. Domino Pd-catalyzed oxidation-arylation reactions of secondary alcohols are also presented.(Figure Presented)
- Landers, Brant,Berini, Christophe,Wang, Chao,Navarro, Oscar
-
experimental part
p. 1390 - 1397
(2011/05/02)
-
- Development of 2,3,5-triaryl-1H-pyrroles as estrogen receptorα selective ligands
-
1-Alkyl-2,3,5-triaryl-1H-pyrroles (for which alkyl=methyl, ethyl, n-propyl, or 2-methylpropyl) were tested for stability, estrogen receptor (ER) binding, and inhibition of tumor cell growth. These pyrroles (typeB) showed higher stability in aqueous solution than their 1,2,4-triaryl-1H-pyrrole congeners (typeA pyrroles), exclusive ERα binding (no ERβ interaction), and a hormonal profile of partial agonists at ERα. The most potent compound, 1-(2-methylpropyl)-2,3,5-tris(4-hydroxyphenyl)-1H-pyrrole (5d), was less active than the lead structure 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (PPT) in MCF-7 cells stably transfected with the plasmid EREwtcluc (MCF-7/2a), but more potent in U2-OS/α cells. Furthermore, 5d showed weak anti-estrogenic properties (IC50=310nM). An additional propyl chain at C4 decreased the stability and pharmacological effects.
- Schaefer, Anja,Wellner, Anja,Strauss, Martin,Wolber, Gerhard,Gust, Ronald
-
scheme or table
p. 2055 - 2062
(2012/07/01)
-
- Synthesis and preliminary in-vitro cytotoxic activity of novel substituted diaryl-imidazo [2, 1, b]-benzothiazole derivatives
-
A novel series of substituted diaryl imidazo[2, 1-b]benzothiazole derivatives (8a-y) were synthesized by condensation reaction between 2-amino benzothiazole derivatives (3a-g) and substituted a-bromo-1, 2-(substituted) diaryl-1-ethanones (7a-i). The structures of the synthesized compounds were established by IR, 1H NMR, 13C NMR and mass spectroscopical data. The compounds (8a-y) were evaluated for their in-vitro cytotoxic activity on murine (B16F10) and human (MCF-7) cancer cells by using MTT assay. From the in vitro studies compounds 8p, 8u and 8y were found most effective with an IC50 range of 0.56-27.50 μM in MCF-7 and 2.57-36.54 μM in B16F10 cells.
- Malik, Jitender K.,Noolvi, Malleshappa N.,Manvi, Fakkirappa V.,Nanjwade,Patel, Harun M.,Manjula,Rao, Mallikarjuna C.,Barve, Ashutosh
-
experimental part
p. 717 - 724
(2012/04/05)
-
- Synthesis and preliminary in-vitro cytotoxic activity of novel substituted diaryl-imidazo [2,1,b]-benzothiazole derivatives
-
A novel series of substituted diaryl imidazo[2,1-b]benzothiazole derivatives (8a-y) were synthesized by condensation reaction between 2-amino benzothiazole derivatives (3a-g) and substituted α-bromo-1, 2-(substituted) diaryl-1-ethanones (7a-i). The structures of the synthesized compounds were established by IR, 1H NMR, 13C NMR and mass spectroscopical data. The compounds (8a-y) were evaluated for their in-vitro cytotoxic activity on murine (B16F10) and human (MCF-7) cancer cells by using MTT assay. From the in vitro studies compounds 8p, 8u and 8y were found most effective with an IC50 range of 0.56-27.50 μM in MCF-7 and 2.57-36.54 μM in B16F10 cells.
- Malik, Jitender K.,Noolvi, Malleshappa N.,Manvi, Fakkirappa V.,Nanjwade,Patel, Harun M.,Manjula,Mallikarjuna Rao,Barve, Ashutosh
-
experimental part
p. 717 - 724
(2012/05/20)
-
- Palladium-catalyzed oxidative coupling of trialkylamines with aryl iodides leading to alkyl aryl ketones
-
Chemical equations presented. A new, simple method for selectively synthesizing alkyl aryl ketones has been developed by palladium-catalyzed oxidative coupling of trialkylamines with aryl iodides. In the presence of PdCl2(MeCN)2, TBAB, and ZnO, a variety of aryl iodides underwent an oxidative coupling reaction with tertiary amines and water to afford the corresponding alkyl aryl ketones in moderate to excellent yields. It is noteworthy that this method is the first example of using trialkylamines as the carbonyl sources for constructing alkyl aryl ketone skeletons.
- Liu, Yan,Yao, Bo,Deng, Chen-Liang,Tang, Ri-Yuan,Zhang, Xing-Guo,Li, Jin-Heng
-
supporting information; experimental part
p. 2184 - 2187
(2011/06/20)
-
- Synthesis and antibacterial activity of a novel series of 2,3-diaryl-substituted-imidazo(2,1-b)-benzothiazole derivatives
-
Benzothiazole and imidazole compounds are extensively studied heterocyclics due to their wide spectrum of bioactivities. Among them, the imidazo(2,1-b)-benzothiazole derivatives are pharmacologically important because of their immunostimulant, anti-inflammatory, antifungal, antimicrobial, antitumor, and other activities. In the present research work, a novel series of 2,3-diaryl-substituted imidazo(2,1-b)-benzothiazoles 13a-o have been synthesized by reaction of substituted 2-aminobenzothiazoles 1-8 and an appropriately substituted a-bromo-1-(4″-substituted)-phenyl-2-(4′- substituted)-phenyl-1-ethanones 9-12 in the presence of anhydrous acetonitrile. They were characterized by physicochemical, elemental, and spectral (IR, 1H-NMR, and Mass) data. All the synthesized compounds were screened for their in-vitro antibacterial activity against Gram-positive, Gram-negative bacteria. The investigation of antibacterial screening data revealed that most of the compounds tested have demonstrated congruent activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa as compared with the standard ampicillin. Among the series, compounds 13d, 13h, and 13m exhibited excellent an antibacterial activity profile as compared with the standard. In summary, preliminary results indicate that some of the newly synthesized title compounds exhibited promising antibacterial activities and they warrant more consideration as prospective antimicrobials.
- Palkar, Mahesh,Noolvi, Malleshappa,Sankangoud, Ramappa,Maddi, Veeresh,Gadad, Andanappa,Nargund, Laxmi Venkat G.
-
experimental part
p. 353 - 359
(2011/07/08)
-
- Pd-catalyzed synthesis of α-aryl ketones through couplings of α-arylacetyl chlorides with triarylbismuths as multi-coupling nucleophiles
-
The cross-coupling reaction of α-arylacetyl chlorides with triarylbismuths was studied under Pd-catalyzed conditions. The reaction was found to be facile under the established protocol and furnished high yields of α-aryl ketones in short reaction times. T
- Rao, Maddali L.N.,Giri, Somnath,Jadhav, Deepak N.
-
experimental part
p. 6133 - 6138
(2010/02/27)
-
- Pd-catalyzed deoxygenation of mandelate esters
-
(Chemical Equation Presented) A new approach to the synthesis of phenylacetic acids and esters has been developed via the palladium-catalyzed deoxygenation of mandelate esters.
- Milne, Jacqueline E.,Murry, Jerry A.,King, Anthony,Larsen, Robert D.
-
supporting information; experimental part
p. 445 - 447
(2009/04/10)
-
- Metal-free reductive cleavage of C-O σ-bonds in acyloin derivatives by an organic neutral super-electron-donor
-
(Chemical Equation Presented) Neutral organic electron-donor 7, formally a pyridinylidene carbene dimer, effects reductive cleavage of C-O σ-bonds in acyloin derivatives Ar(CO)CRR′OX (X = OAc, OPiv, OBz, OMs) and this represents the first cleavage of C-O σ-bonds by a neutral organic electron-donor. The methodology is applicable to a large array of substrates and the reduced counterparts were isolated in good to excellent yields. For certain substrates, donor 7 behaves as a base, effecting condensation reactions with some acetate ester derivatives of acyloins, leading to butenolides. The variation in reactivity among the different substrates was rationalized. 2009 American Chemical Society.
- Cutulic, Sylvain P. Y.,Findlay, Neil J.,Zhou, Sheng-Ze,Chrystal, Ewan J. T.,Murphy, John A.
-
supporting information; experimental part
p. 8713 - 8718
(2009/12/28)
-
- TRIPHENYL MODIFIED 5-MEMBERED HETEROCYCLES AND THEIR USE AS ANTICANCER AND ANTIINFLAMMATORY AGENTS
-
The present invention provides 5-membered heterooycles, preferably pyrrole furans and thiophenes, with three phenyl moieties wherein at least one of the three Phenyl moieties is substituted with halogen and alkoxy, halogen and hydrox trihalomethy, and alkoxy, trihatomethyl and hydroxy or halogen and alky, an wherein a second phenyl moiety is substituted with at least hydroxy or alkoxy The compounds of the invention show antiproliferative effects and inhibitory effects on cyclooxygenases (COX-1 and COX-2). Therefore the invention is also directed to the use of said compounds for the manufacture of a pharmaceutic composition for prevention and treatment of cancer and/or inflammatory diseases The invention further concerns a method for treating cancer or an inflammator disease, which comprises the step of administering to a patient suffering from that disease a therapeutically effective amount of at least one of said compounds.
- -
-
Page/Page column 15
(2010/11/29)
-
- Synthesis and biological evaluation of 2-trifluoromethyl/sulfonamido-5,6-diaryl substituted imidazo[2,1-b]-1,3,4-thiadiazoles: A novel class of cyclooxygenase-2 inhibitors
-
A series of 2-trifluoromethyl/sulfonamido-5,6-diarylsubstituted imidazo[2,1-b]-1,3,4-thiadiazole derivatives 15a-j have been synthesized by the reaction of 2-amino-5-trifluoromethyl/sulfonamido-1,3,4-thiadiazoles 14a-b and appropriately substituted α-bromo-1,2-(p-substituted)diaryl-1-ethanones 13a-h. Structures of these compounds were established by IR, 1H NMR, 13C NMR, Mass, and HRMS data. The selected compounds were evaluated for their preliminary in vitro cyclooxygenase inhibitory activity against COX-2 and COX-1enzymes using colorimetric method. The compounds tested showed selective inhibitory activity toward COX-2 (80.6-49.4%) over COX-1 (30.6-8.6), amongst them compounds 15f and 15j showed appreciable COX-2 selective inhibitory activity. These compounds also exhibited significant anti-inflammatory activity (70.09-42.32%), which is comparable to that of celecoxib in the carrageenan-induced rat paw edema method.
- Gadad, Andanappa K.,Palkar, Mahesh B.,Anand,Noolvi, Malleshappa N.,Boreddy, Thippeswamy S.,Wagwade
-
p. 276 - 283
(2008/03/28)
-
- Efficient synthesis of deoxybenzoins from chalcones
-
β-Ketoaldehydes derived from chalcone epoxides by Lewis acid-catalyzed rearrangement underwent smooth deformylation when refluxed in tetrahydrofuran (THF) in the presence of ethylenediamine, affording deoxybenzoins in excellent yields. The method is general and useful for the preparation of deoxybenzoins with a variety of substitution patterns. Copyright Taylor & Francis Group, LLC.
- Mathew, Paulson,Mathew, Daliya,Asokan
-
p. 661 - 665
(2007/10/03)
-
- Application of the catalytic friedel-crafts acylation reaction and regioselectivity correlations
-
A correlation was found between electronic properties and regioselectivity in the Friedel-Crafts reaction of substituted phenylacetic and benzoic acids with anisole, utilising substoichiometric (down to 1 mol%) amounts of catalyst. Relative reactivities of selected catalysts for this reaction were also studied. Georg Thieme Verlag Stuttgart.
- Wilkinson, Mark C.,Saez, Fabienne,Wei, Lee Hon
-
p. 1063 - 1066
(2007/10/03)
-
- Reactions of aroyl chlorides with samarium metal in DMF-controllable syntheses of O-aroylbenzoins, 1,2-diarylethanones, and (z)-α, α′-stilbenediol dibenzoates
-
Reduction of aroyl chlorides carried out in DMF with samarium metal has been studied. Samarium metal, which requires not any intended activation or pretreatment, was found to react with aroyl chloride in a controllable manner. Correspondingly, O-aroylbenzoins, 1,2-diarylethanones, or (Z)-α, α′-stilbenediol dibenzoates were afforded as the major products under controlled conditions.
- Liu, Yongjun,Wang, Xiaoxia,Zhang, Yongmin
-
p. 4009 - 4022
(2007/10/03)
-
- Antiestrogenically active 1,1,2-tris(4-hydroxyphenyl)alkenes without basic side chain: Synthesis and biological activity
-
C2-Alkyl substituted derivatives of the 1,1,2-tris(4-hydroxyphenyl)ethene 3a (alkyl = Me (3b), Et (3c), Prop (3d), But (3e)) were synthesized by reaction of 1,2-bis(4-methoxyphenyl)ethanone with the appropriate alkyl halide, followed by a Grignard reaction with 4-methoxyphenylmagnesium bromide, dehydration with phosphoric acid or hydrobromic acid, and ether cleavage with BBr3. The compounds were tested for estrogen receptor (ER) binding affinity in a competition experiment with radio labeled estradiol ([3H]-E2) and for gene activation on the ER-positive MCF-7-2a cell line. All compounds showed high receptor binding affinity (RBA-value: 3b (52. 1%) > 3a (45.5%) > 3c (29.6%) > 3d (4.03%) > 3e (0.95%)). The tests on hormone dependent MCF-7-2a breast cancer cells, stably transfected with the plasmid EREwtcluc, revealed that all 1,1,2-tris(4-hydroxyphenyl)ethenes antagonized the effect of 1 nM estradiol (E2). The compounds 3b (IC50 = 15 nM) and 3c (IC50 = 10 nM) were equal in their effects to 4-hydroxytamoxifen (4OHT) (IC50 = 7 nM). Agonistic effects were low. Only 3a and 3b activated the luciferase expression (relative activation at 1 μM: 3a 60%; 3b 35%). Despite their highly antagonistic potency, the 1,1,2-tris(4-hydroxyphenyl)ethenes showed only low cytotoxic properties on the hormone sensitive MCF-7 cell line.
- Lubczyk, Veronika,Bachmann, Helmut,Gust, Ronald
-
p. 1484 - 1491
(2007/10/03)
-
- Efficient and practical solvent-free oxidation of alcohols using microwave irradiation
-
Alcohols are oxidised rapidly to the corresponding carbonyl compounds by montmorillonite KSF or silica supported barium manganate, under solvent-free conditions and microwave irradiation.
- Mojtahedi, Mohammad M.,Sharifi, Ali,Kaamyabi, Sharif,Saidi, Mohammad R.
-
p. 286 - 287
(2007/10/03)
-
- Microwave assisted selective oxidation of benzylic alcohols with calcium hypochlorite under solvent-free conditions
-
A remarkably fast microwave assisted selective oxidation of benzylic alcohols with calcium hypochlorite under solvent-free conditions is described.
- Mojtahedi, Mohammad M.,Saidi, Mohammad R.,Bolourtchian, Mohammad,Shirzi, Jafar S.
-
p. 655 - 658
(2007/10/03)
-
- Modulation of lifetimes and diastereomeric discrimination in triplet- excited substituted butane-1,4-diones through intramolecular charge-transfer quenching
-
Triplet lifetimes have been determined for the diastereomers of a broad set of butane-1,4-dione derivatives (1-3). A remarkable dependence of lifetimes on conformational preferences is revealed in that the lifetimes are shorter for the meso diastereomers of 1-3 than those for the racemic ones. The intramolecular β-phenyl quenching is promoted in the case of meso diastereomers by virtue of the gauche relationship between the excited carbonyl group and the β-aryl ring, while a distal arrangement in the lowest energy conformation (H-anti) in racemic diastereomers prevents such a deactivation. The involvement of charge transfer in the intramolecular β- phenyl quenching is suggested by the correlation of the triplet lifetimes of the meso diastereomers of compounds 2 with the nature of the substituent on the β-phenyl rings. In the case of racemic diastereomers, p-methoxy substitution on the β-phenyl ring (2-OCH3, 3-OCH3) also led to a decrease of the triplet lifetimes when compared to those of the nonsubstituted compounds (2-H, 3-H). This shortening is accounted for by the deactivation of a small proportion of the excited molecules through β-phenyl quenching. In addition to the above factors, the lifetimes in the case of meso diastereomers can further be controlled by increasing the energy spacing between the T1 and T2 states, since β-phenyl quenching occurs from the latter for compounds 2 and 3. Through a rational conformational control, a surprisingly long triplet lifetime (300 ns) has been measured for the first time for a purely n,π* triplet-excited β-phenylpropiophenone dimer (1- rac).
- Moorthy,Monahan,Sunoj,Chandrasekhar,Bohne
-
p. 3093 - 3103
(2007/10/03)
-
- Gas-phase pyrolysis in organic synthesis. Part 2. Novel rearrangement of esters and ethers into aryl ketones
-
The formate ester of benzoin (1) and the methyl ethers of benzoin and anisoin (2, 3) have been converted separately under thermal gas-phase conditions cleanly into 1,2-diarylethanone and have given, respectively, the following Arrhenius log A (s-1) and Ea (kJ mol-1): 10.11 and 132.0, 11.29 and 173.0, and 11.85 and 151.1. A plausible mechanism is suggested to account for these transformations based on the kinetics and products of reaction.
- Al-Awadi, Nouria A.,Kaul, Kamini,El-Dusouqui, Osman M.E.
-
p. 1922 - 1925
(2007/10/03)
-
- Organophosphorous chemistry: Selective transformation of benzoin to benzil, desyl bromide, or benzyl phenyl ketone
-
Reaction of benzoin with dibromotriphenylphosphorane under various conditions has been closely investigated. Benzoin was selectively converted to desyl bromide by treatment with dibromotriphenylphosphorane in the presence of triethylamine, while benzyl phenyl ketone was formed in the presence of an excess amount of triphenylphosphine. On the other hand, benzoin was effectively oxidized to benzil by treatment with only bromine. The mechanism of producing these was also proposed. Desyl bromide was formed from the reaction of benzoin with dibromotriphenylphosphorane as a primary product and converted to benzyl phenyl ketone via the Perkow reaction, and benzil was formed by the oxidation of benzoin by bromine. When triethylamine or triphenylphosphine was used as an added base, these bases trapped free bromine, and the oxidation product, benzil, was formed in low yield. In the presence of triphenylphosphine as a base, the Perkow reaction of desyl bromide proceeded smoothly to give benzyl phenyl ketone preferentially, while in the presence of triethylamine, replacement of the hydroxy group to bromide occurred mainly.
- Furukawa, Isao,Sasaki, Mitsuhiro,Inoue, Takeshi,Ohta, Tetsuo
-
-
- Cis-trans isomerization and oxidation of radical cations of stilbene derivatives
-
Isomerization from cis stilbene derivatives (c-S (S = RCH=CHC6H5: 1, R = C6H5; 2, R = 4-CH3C6H4; 3, R = 4-CH3OC6H4 (= An); 4, R = 2,4-(CH3O)2C6H3; 5, R = 3,4-(CH3O)2C6H3; 6, R = 3,5-(CH3O)2C6H3; 7, AnCH=C(CH3)C6H5; 8, AnCH=CHAn)) to trans isomers (t-S) and oxidation of S with O2 were studied in γ-ray radiolyses of c-S in Ar-saturated 1,2-dichloroethane (DCE) and of S in O2-saturated DCE, respectively. On the basis of product analyses, it is suggested that a smaller barrier to c-t unimolecular isomerization for c-3.+-5.+ and 8.+ than for c-1.+, 2.+, and 6.+ due to the single bond character of the central C=C double bond for c-3.+-5.+ and 8.+ with a p-methoxyl group but not for c-l.+, 2.+, and 6.+ without a p-methoxyl group because of the contribution of a quinoid-type structure induced by charge-spin separation. The isomerization proceeds via chain reaction mechanisms involving c-t unimolecular isomerization and endergonic hole transfer or dimerization and decomposition. The isomerization of c-3.+ to t-3.+ is catalyzed by addition of 1,4-dimethoxybenzene but terminated by triethylamine. The regioselective formation of 3d in oxidation of 3.+ with O2 is explained by spin localization on the β-olefinic carbon in 3.+. The results of product analyses are compared with the rate constants of the unimolecular isomerization and the oxidation for S.+ measured with pulse radiolyses.
- Majima, Tetsuro,Tojo, Sachiko,Ishida, Akito,Takamuku, Setsuo
-
p. 7793 - 7800
(2007/10/03)
-
- Substituted (1,2-Diarylethyl)amide Acyl-CoA:Cholesterol Acyltransferase Inhibitors: Effect of Polar Groups on in Vitro and in Vivo Activity
-
Substituted (1,2-diarylethyl)amides have been prepared and evaluated for their ability to inhibit microsomal acyl-CoA:cholesterol acyltransferase activity in vitro and to lower hepatic cholesteryl ester content in vivo in a cholesterol-fed hamster.Simple unsubstituted (diarylethyl)amides were potent inhibitors in vitro but showed poor activity in vivo.Introduction of polar groups at specific locations on the diarylethylamine moiety decreased in vitro activity but increased in vivo activity.Both effects were highly structure dependent, suggesting specific interactions which were mediating activity in each model.Optimization of these opposing effects led to compounds which were potent in both models.
- Clader, John W.,Berger, Joel G.,Burrier, Robert E.,Davis, Harry R.,Domalski, Martin,et al.
-
p. 1600 - 1607
(2007/10/02)
-
- Acid Reactions of Hydrobenzoins: Effect of Catalyst and Reaction Medium on Product Composition
-
Acid treatment of hydroanisoin in dioxane-water mixtures results in the formation of 2,2-bis(4-methoxyphenyl)ethanal and 1,2-bis(4-methoxyphenyl)ethanone.The relative proportions of these products have been shown to be dependent on the nature of the catalyst and the composition of the reaction medium.The formation of the ketone was catalysed by HCl and by HBr; a variety of other catalysts (e.g.CF3SO3H, H2SO4, HClO4 and HBF4) gave only traces of this compound.Ketone formation is more efficiently catalysed by HBr than HCl.The catalytic effect of HBr essentially disappeared when the solvent composition was changed from dioxane-water (9:1) to dioxane-water (7:3).Analogous results were obtained in studies of the acid degradation of hydroveratroin.
- Karlsson, Olov,Lundquist, Knut
-
p. 283 - 289
(2007/10/02)
-