- Rearrangements in the Molecular Ion of o-(Methyl-d3-thio)benzoic acid: Comparison with o-Methoxy-d3-benzoic Acid
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Hydrogen/deuterium exchange and rearrangements in the molecular ion of o-(methyl-d3-thio)benzoic acid lead to fragment ions + as well as + and m/z 106 and 107, just as in the molecular ion of o-methoxybenzoic a
- Gillis, Richard G.,Porter, Quentin N.
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Read Online
- Photocatalytic Deoxygenation of Sulfoxides Using Visible Light: Mechanistic Investigations and Synthetic Applications
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The photocatalytic deoxygenation of sulfoxides to generate sulfides facilitated by either Ir[(dF(CF3)ppy)2(dtbbpy)]PF6 or fac-Ir(ppy)3 is reported. Mechanistic studies indicate that a radical chain mechanism operates, which proceeds via a phosphoranyl radical generated from a radical/polar crossover process. Initiation of the radical chain was found to proceed via two opposing photocatalytic quenching mechanisms, offering complementary reactivity. The mild nature of the radical deoxygenation process enables the reduction of a wide range of functionalized sulfoxides, including those containing acid-sensitive groups, in typically high isolated yields.
- Clarke, Aimee K.,Parkin, Alison,Rossi-Ashton, James A.,Taylor, Richard J. K.,Unsworth, William P.
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p. 5814 - 5820
(2020/07/21)
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- Palladium-Catalyzed C-S Bond Formation as a Tool for Latent-Active Glycosylation
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A high-yielding palladium-catalyzed C-S cross-coupling is presented for utilization in carbohydrate chemistry as a key transformation for attachment of a second chelating sulfur atom that allows the exploitation of a latent-active glycosylation strategy w
- Hedberg, Christinne,Jessen, Kamilla S.,Hansson, Rikke F.,Heuckendorff, Mads,Jensen, Henrik H.
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supporting information
p. 7068 - 7072
(2020/10/02)
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- Design, synthesis and biological activity of selective hCAs inhibitors based on 2-(benzylsulfinyl)benzoic acid scaffold
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A large library of derivatives based on the scaffold of 2-(benzylsulfinyl)benzoic acid were synthesised and tested as atypical inhibitors against four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). The exploration of the chemical space around the main functional groups led to the discovery of selective hCA IX inhibitors in the micromolar/nanomolar range, thus establishing robust structure-activity relationships within this versatile scaffold. HPLC separation of some selected chiral compounds and biological evaluation of the corresponding enantiomers was performed along with molecular modelling studies on the most active derivatives.
- Rotondi, Giulia,Guglielmi, Paolo,Carradori, Simone,Secci, Daniela,De Monte, Celeste,De Filippis, Barbara,Maccallini, Cristina,Amoroso, Rosa,Cirilli, Roberto,Akdemir, Atilla,Angeli, Andrea,Supuran, Claudiu T.
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p. 1400 - 1413
(2019/08/26)
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- INDOLE DERIVATIVE USED AS CRTH2 INHIBITOR
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The present application discloses an indole as represented by formula (I) used as a CRTH2 inhibitor, and a pharmaceutically acceptable salt or tautomer of the indole, and an application of same in treating a disease related to a CRTH2 receptor.
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Paragraph 0078-0079
(2019/06/07)
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- Indole derivative serving as CRTH2 inhibitor
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The invention discloses an indole derivative serving as a CRTH2 inhibitor shown as a formula (I) as shown in the specification or pharmaceutically acceptable salts, as well as application of the indole derivative in treatment of diseases related to the CR
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Paragraph 0088; 0089; 0090
(2018/05/16)
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- DNA binding and antitumor activities of platinum(IV) and zinc(II) complexes with some S-alkyl derivatives of thiosalicylic acid
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A series of complexes of platinum(IV) (C1–C5) and zinc(II) (C6–C10) with S-alkyl derivatives of thiosalicylic acid were prepared and characterized. The interactions of the complexes with calf thymus DNA were analyzed by absorption (UV–Vis) and emission spectral studies (ethidium bromide displacement studies). The cytotoxic activities of complexes C1–C10 were determined against mouse B cell lymphocytic leukemia cells (BCL1), human B-prolymphocytic leukemia (JVM-13), mouse mammary carcinoma cells (4T1), and human mammary carcinoma cells (MDA-MB-468) and compared to the activities of the free ligand precursors and cisplatin. The cytotoxicities of the platinum(IV) and zinc(II) complexes toward mouse tumor cell lines were higher compared with their effects on human tumor cell lines. The zinc(II) complex C9 showed the highest antitumor activity toward the tested human cell lines, while the platinum(IV) complex C4 exhibited the highest antitumor activity toward mouse BCL1 and 4T1 cells. Both C4 and C9 have ligands derived from S-propyl thiosalicylic acid.
- Besser Silconi, Zana,Benazic, Sasa,Milovanovic, Jelena,Jurisevic, Milena,Djordjevic, Dragana,Nikolic, Milos,Mijajlovic, Marina,Ratkovic, Zoran,Radi?, Gordana,Radisavljevic, Snezana,Petrovic, Biljana,Radosavljevic, Gordana,Milovanovic, Marija,Arsenijevic, Nebojsa
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p. 719 - 729
(2018/07/31)
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- Copper(I)-Catalyzed Alkyl- and Arylsulfenylation of 3,4-Dihalo-2(5H)-furanones (X=Br, Cl) with Sulfoxides under Mild Conditions
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An efficient copper(I)/proline sodium salt-catalyzed alkyl- and arylsulfenylation of C(sp2)–X 3,4-dihalo-2(5H)-furanone compounds with sulfoxides is described. For inexpensive C(sp2)–Cl compounds, there is also a satisfactory reactivity with the moderate yields. This transformation provides a novel approach for the utilization of sulfoxides (not only DMSO) as sulfur source at mild temperatures without the need for an anaerobic atmosphere. More importantly, both sulfoxide and proline sodium salt can play a dual role in this reaction. (Figure presented.).
- Cao, Liang,Luo, Shi-He,Wu, Han-Qing,Chen, Liu-Qing,Jiang, Kai,Hao, Zhi-Feng,Wang, Zhao-Yang
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supporting information
p. 2961 - 2971
(2017/09/08)
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- Bistable Photoswitching of Hemithioindigo with Green and Red Light: Entry Point to Advanced Molecular Digital Information Processing
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Photoswitches reacting to visible light instead of harmful UV irradiation are of very high interest due to the mild and broadly compatible conditions of their operation. Shifting the absorption into the red region of the electromagnetic spectrum usually comes at the cost of losing thermal stability of the metastable state—the switch switches off by itself. Only recently have photoswitches become available that combine visible light responsiveness with high bistability. However, shifting the wavelengths for bistable photoswitching beyond 600 nm is still a great challenge without involving secondary processes such as two-photon absorption or sensitization. We present a simple hemithioindigo photoswitch that can efficiently be photoisomerized using green and red light while maintaining a high thermal barrier of the metastable state. This highly sought after properties allow for selective switching in a mixture of hemithioindigo dyes. In addition, protonation can be used as second independent input altering the light response of the switch and allowing construction of advanced molecular digital information processing devices. This is demonstrated by realizing a broad variety of logical operations covering combinational and sequential logic behavior. By making use of the protonation-induced loss of thermal bistability, a high security keypad lock could be realized, which distinguishes the sequences of three different inputs and additionally erases its unlocked state after a short time.
- Kink, Florian,Collado, Marina Polo,Wiedbrauk, Sandra,Mayer, Peter,Dube, Henry
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supporting information
p. 6237 - 6243
(2017/05/12)
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- New piperazine derivatives having anti-cancer effect, combination therapeutic effect with radiation, and anti-diabetic effect, and PPAR activity, and medical use thereof
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The present invention relates to a novel piperazine derivative having an anti-cancer effect, a combination therapeutic effect with radiation, and an anti-diabetic effect, and to a medical use thereof. The piperazine derivatives are PPAR-γ ligand, and have
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Paragraph 0068; 0069; 0072; 0073
(2018/10/03)
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- Cytotoxicity of copper(II)-complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II)-complex with S-ethyl derivative of thiosalicylic acid
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The spectroscopically predicted structure of the obtained copper(II)-complex with S-ethyl derivative of thiosalicylic acid was confirmed by X-ray structural study and compared to previously reported crystal structure of the Cu complex with S-methyl deriva
- Nikoli?, Milo? V.,Mijajlovi?, Marina ?.,Jevti?, Verica V.,Ratkovi?, Zoran R.,Novakovi?, Sladjana B.,Bogdanovi?, Goran A.,Milovanovi?, Jelena,Arsenijevi?, Aleksandar,Stojanovi?, Bojana,Trifunovi?, Sre?ko R.,Radi?, Gordana P.
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p. 264 - 271
(2016/04/04)
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- Synthesis and characterization of ortho-thio-functionalized triarylmethyl palladium complexes
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A series of triarylmethyl palladium complexes with ortho coordination sites were synthesized. Thereby, the palladium atom exhibits various inter- and intramolecular binding modes towards the organic ligand. Further, the first crystallographically proven, exclusively σ-coordinated triarylmethyl palladium complexes, stabilized by ortho-thio-substituents, were discovered. The NMR spectra of the palladium complexes indicate temperature-dependent dynamic behavior.
- Sch?ler, Stephan,Merz, Klaus,Puls, Arik,Winter, Manuela,Dyker, Gerald
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supporting information
p. 53 - 57
(2015/01/30)
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- Cytotoxicity of palladium(II) complexes with some alkyl derivates of thiosalicylic acid. Crystal structure of the bis(S-butyl-thiosalicylate)palladium(II) complex, [Pd(S-bu-thiosal)2]
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The spectroscopically predicted structure of the obtained bis(S-butyl-thiosalicylate)palladium(II) complex, [Pd(S-bu-thiosal)2], was confirmed by an X-ray structural study. The asymmetric unit of [Pd(S-bu-thiosal)2] consists of neutr
- Mijajlovi?, Marina ?.,Nikoli?, Milo? V.,Jevti?, Verica V.,Ratkovi?, Zoran R.,Markovi?, Bojana Simovi?,Volarevi?, Vladislav,Arsenijevi?, Neboj?a N.,Novakovi?, Sladjana B.,Bogdanovi?, Goran A.,Trifunovi?, Sre?ko R.,Radi?, Gordana P.
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- Discovery and structure-activity relationship studies of N6-benzoyladenine derivatives as novel BRD4 inhibitors
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Bromodomain and extra-terminal domain (BET) proteins are epigenetic readers that bind to acetylated lysines in histones. Among them, BRD4 is a candidate target molecule of therapeutic agents for diverse diseases, including cancer and inflammatory disease.
- Noguchi-Yachide, Tomomi,Sakai, Taki,Hashimoto, Yuichi,Yamaguchi, Takao
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p. 953 - 959
(2015/03/04)
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- Synthesis, characterization and antimicrobial activity of copper(II) complexes with some S-alkyl derivatives of thiosalicylic acid. Crystal structure of the binuclear copper(II) complex with S-methyl derivative of thiosalicylic acid
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The five new copper(II) complexes with some S-alkyl derivatives of thiosalicylic acid (alkyl = benzyl (L1), methyl (L2), ethyl (L3), propyl (L4), butyl (L5)) have been synthesized and characterized by microanalysis and infrared spectra. The spectroscopica
- Nikoli?, Milo? V.,Mijajlovi?, Marina ?.,Jevti?, Verica V.,Ratkovi?, Zoran R.,Radojevi?, Ivana D.,?omi?, Ljiljana R.,Novakovi?, Sladjana B.,Bogdanovi?, Goran A.,Trifunovi?, Sre?ko R.,Radi?, Gordana P.
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- Surface modification of MoS2 nanoparticles with ionic liquid-ligands: Towards highly dispersed nanoparticles
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Highly dispersible MoS2 nanoparticles have been prepared via surface-modification using a novel tetraethylene glycol-based ionic liquid containing a chelating moiety attached to the cation. The choice of the respective ligand enables the genera
- Osim, Wilton,Stojanovic, Anja,Akbarzadeh, Johanna,Peterlik, Herwig,Binder, Wolfgang H.
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supporting information
p. 9311 - 9313
(2013/10/01)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes with bis(pyridine)silver permanganate
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The oxidation of thirty-six ortho-, meta- and para-substituted benzaldehydes by bis(pyridine)silver permanganate (BPSP) resulted in the formation of the corresponding benzoic acids. The reaction is first order with respect to both BPSP and aldehydes. The reaction is catalyzed by hydrogen ions. The rate of reaction increases with an increase in the amount of acetic acid in the solvent. The correlation analyses of the rate of oxidation of thirty-six aldehydes were performed in terms of Charton's LDR and LDRS equations. The rate of oxidation of meta- and para-substituted benzaldehydes showed excellent correlation with Charton's LDR equation. The rates of ortho-compounds showed excellent correlation with LDRS equation. The oxidation para-compounds is more susceptible to the delocalization effect. The oxidation of ortho- and meta-compounds exhibited a greater dependence on the field effect. The polar reaction constants are negative indicating an electron-deficient centre in the rate-determining step. A mechanism involving a nucleophilic attack on the carbonyl group by a permanganate-oxygen and a subsequent hydride transfer has been proposed.
- Purohit, Trupti,Banerji, Jayshree,Kotai, Laszlo,Sajo,Banerji,Sharma, Pradeep K.
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p. 1045 - 1052
(2013/01/14)
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- Pinacol as a new green reducing agent: Molybdenum-catalyzed chemoselective reduction of sulfoxides and nitroaromatics
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Pinacol is disclosed as a new chemoselective and environmentally benign reducing agent for sulfoxides and nitroaromatics assisted by readily available dichlorodioxomolybdenum(VI) complexes as catalysts. A wide range of substrates including those bearing challenging functional groups has been efficiently and selectively reduced with acetone and water being the only by-products of these reactions. Copyright
- Garcia, Nuria,Garcia-Garcia, Patricia,Fernandez-Rodriguez, Manuel A.,Rubio, Ruben,Pedrosa, Maria R.,Arnaiz, Francisco J.,Sanz, Roberto
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supporting information; experimental part
p. 321 - 327
(2012/04/11)
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- Synthesis, characterization and antimicrobial activity of palladium(II) complexes with some alkyl derivates of thiosalicylic acids: Crystal structure of the bis(S-benzyl-thiosalicylate)-palladium(II) complex, [Pd(S-bz-thiosal) 2]
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S-Alkyl (R = benzyl, methyl, ethyl, propyl and butyl) derivatives of thiosalicylic acid and the corresponding palladium(II) complexes were prepared and their structures were proposed on the basis of infrared, 1H and 13C NMR spectrosc
- Radic, Gordana P.,Gloovic, Verica V.,Radojevic, Ivana D.,Stefanovic, Olgica D.,Comic, Ljiljana R.,Ratkovic, Zoran R.,Valkonen, Arto,Rissanen, Kari,Trifunovic, Srecko R.
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experimental part
p. 69 - 76
(2012/03/13)
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- Structure-Reactivity correlation in the oxidation of substituted benzaldehydes by tetraethylammonium chlorochromate
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Oxidation of 36 monosubstituted benzaldehydes by tetraethylammonium chlorochromate in dimethyl sulphoxide, leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to chlorochromate and aldehydes. The reaction is promoted by H+; the H+ dependence has the form kobs = a + b[H+]. The oxidation of duteriated benzaldehyde exhibits substantial primary kinetic isotope effect. The reaction was studied in 19 different organic solvents and the effect of solvent was analyzed using Taft's and Swain's multiparametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of h suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the orthosubstituents. A suitable mechanism has been proposed.
- Gehlot,Prasadrao,Sharma
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experimental part
p. 1173 - 1178
(2012/01/05)
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- Enhanced stereoselectivity of a Cu(II) complex chiral auxiliary in the synthesis of Fmoc-L-γ-carboxyglutamic acid
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L-γ-Carboxyglutamic acid (Gla) is an uncommon amino acid that binds avidly to mineral surfaces and metal ions. Herein, we report the synthesis of N-R-Fmoc-L-γ-carboxyglutamic acid γ, γ0-tert-butyl ester (Fmoc-Gla(OtBu)2-OH), a suitably protected analogue for Fmoc-based solid-phase peptide synthesis. The residue was synthesized using a novel chiral Cu(II) complex, whose structurebased design was inspired by the blue copper protein rusticyanin. The five-coordinate complex is formed by Shiff base formation between glycine and the novel ligand (S)-2-(N-(2-methylthio)benzylprolyl) aminobenzophenone in the presence of copper. Michael addition of di-tert-butyl methylenemalonate to the R-carbon of the glycine portion of the complex occurs in a diastereoselective fashion. The resulting (S,S)-complex diastereomer can be easily purified by chromatography. Metal complex decomposition followed by Fmoc protection affords the enantiomerically pure amino acid. With the use of this novel chiral complex, the asymmetric synthesis of Fmoc-Gla(OtBu)2-OH was completed in nine steps from thiosalicylic acid in 14.5% overall yield.
- Smith, Daniel J.,Yap, Glenn P.A.,Kelley, James A.,Schneider, Joel P.
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experimental part
p. 1513 - 1520
(2011/06/20)
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- An umpolung sulfoxide reagent for use as a functionalized benzyl carbanion equivalent
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N-Methyl ortho-carbamoylaryl benzyl sulfoxides can be used as synthetic equivalents for α-hydroxy, α-chloro, and α-acetammido benzyl carbanions by means of a two-step sequence involving highly diastereoselective α-C-alkylation with alkyl halides followed by displacement of the sulfinyl residue (which can be recovered and recycled) by a hydroxyl, a chlorine or an acetamido, respectively, under non-oxidative Pummerer conditions. The scope and limits of the method, including a stereoselective version of the reaction, as well as the mechanism of the process are discussed in detail.
- Pinna, Giovanni,Bellucci, Maria Cristina,Malpezzi, Luciana,Pisani, Laura,Superchi, Stefano,Volonterio, Alessandro,Zanda, Matteo
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experimental part
p. 5268 - 5281
(2011/08/06)
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- Syntheses, structures, and catalytic activities of hemilabile thioether-functionalized NHC complexes
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Four imidazolium (5a/b) and benzimidazolium (6a/b) salts with hemilabile alkyl-aryl thioether functions have been prepared via a straightforward and modular pathway in order to compare their reactivities toward palladation. Reaction of 5a/b with Pd(OAc)s
- Huynh, Han Vinh,Yeo, Chun Hui,Chew, Ying Xia
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experimental part
p. 1479 - 1486
(2010/05/15)
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- Synthesis, spectral characterization and electrochemical properties of (2-alkylthiobenzoyl)ferrocenes. Crystal structures of 2-methylthio, 2-ethylthio and 2-isopropylthio derivatives
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The one-pot synthesis of seven new (2-alkylthiobenzoyl)ferrocenes has been achieved by Friedel-Crafts acylation of ferrocene with acid chlorides generated in situ from the corresponding carboxylic acids and phosphorous trichloride. The obtained compounds
- Ratkovi?, Zoran,Novakovi?, Sladana B.,Bogdanovi?, Goran A.,?egan, Dejan,Vuki?evi?, Rastko D.
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scheme or table
p. 2311 - 2317
(2010/09/06)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by morpholinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldehydes by morpholinium chlorochromate (MCC) in dimethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to MCC. A Michaelis-Menten type kinetics is observed with respect to benzaldehydes. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs = a + b [H+]. The oxidation of [2H] benzaidehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Choudhary, Anurag,Malani,Agarwal,Sharma,Sharma, Vinita
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experimental part
p. 927 - 935
(2010/07/16)
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- Structure-reactivity correlation in the oxidation of substituted benzaldehydes by 2,2-bipyridinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldchydes by 2,2′-bipyridiniuin chlorochromate (BPCC) in diniethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to both BPCC and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen ion dependence has the form kobs= a + b[H+]. The oxidation of [2H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and mete-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of orfAo-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and mem-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Sharma, Pradeep K.
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experimental part
p. 1281 - 1288
(2009/12/31)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by tetrabutylammonium tribromide
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The oxidation of thirty-six monosubstituted benzaldehydes by tetrabutylammonium tribromide (TBATB), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both TBATB and aldehydes. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride ions on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the medium. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Chouhan,Sharma, Monica,Sharma, Vinita
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p. 582 - 587
(2008/09/21)
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- Facile electrochemical transformation of diazonium salts into carboxylic acids
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The electrolyses of aryldiazonium tetrafluoroborates in dry DMF and Bu4NHSO4 as solvent-supporting electrolyte system, in the presence of CO2 led to the corresponding arylcarboxylic acids in very good yields.
- Otero, M. Dolores,Batanero, Belen,Barba, Fructuoso
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p. 8215 - 8216
(2007/10/03)
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- Hemilabile behavior of a thioether-functionalized N-heterocyclic carbene ligand
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The truely hemilabile nature of a novel thioether-functionalized N-heterocyclic carbene ligand is demonstrated in a range of Pd(ii) complexes. The Royal Society of Chemistry 2006.
- Huynh, Han Vinh,Yeo, Chun Hui,Tan, Geok Kheng
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p. 3833 - 3835
(2007/10/03)
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- Highly chemoselective methylation and esterification reactions with dimethyl carbonate in the presence of NaY faujasite. The case of mercaptophenols, mercaptobenzoic acids, and carboxylic acids bearing OH substituents
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In the presence of NaY faujasite, the reactions of dimethyl carbonate (DMC) with several ambident nucleophiles such as o- and p-mercaptophenols (1a,b), o- and p-mercaptobenzoic acids (2a,b), o- and p-hydroxybenzoic acids (3a,b), mandelic and phenyllactic acids (4, 5), have been explored under batch conditions. Highly chemoselective reactions can be performed: at 150 °C, compounds 1 and 2 undergo only a S-methylation reaction, without affecting OH and CO2H groups; at 165 °C, acids 3-5 form the corresponding methyl esters, while both their aromatic and aliphatic OH substituents are fully preserved from methylation and/or transesterification processes. Typical selectivities are of 90-98% and isolated yields of products (S-methyl derivatives and methyl esters, respectively) are in the range of 85-96%. A comparative study with K2CO3 as a catalyst is also reported. Although the base (K2CO3) turns out to be more active than the zeolite, the chemoselectivity is elusive: compounds 2a,b undergo simultaneous S-methylation and esterification reactions, and acids 3-5 yield complex mixtures of products of O-methylation, O-methoxycarbonylation, and esterification of their OH and CO2H groups, respectively. Overall, the combined use of a nontoxic reagent/solvent (DMC) and a safe promoter (NaY) imparts a genuine ecofriendly nature to the investigated synthesis.
- Selva, Maurizio,Tundo, Pietro
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p. 1464 - 1470
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by benzyltrimethylammonium tribromide
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The oxidation of benzaldehyde and thirty-five monosubstituted benzaldehydes by benzyltrimethylammonium tribromide (BTMAB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids, The reaction is first order with respect to each the benzaldehyde and BTMAB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes are correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes are correlated with tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho-and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho-substituents.
- Mehla, Satish K.,Kothari, Seema,Banerji, Kalyan K.
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p. 832 - 838
(2007/10/03)
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- An umpolung sulfoxide reagent as α-hydroxy and α-chloro benzyl carbanion equivalents
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ortho-[(N-Methyl)carbamoyl]phenyl benzyl sulfoxide is used as a synthetic equivalent of α-hydroxy and α-chloro benzyl carbanions by means of a two-step sequence involving (1) highly stereoselective α-C-alkylation with alkyl bromides, and (2) displacement of the sulfinyl group by an OH or a Cl under Pummerer or chloro-Pummerer conditions, respectively. The sulfinyl auxiliary can be effectively regenerated and recycled.
- Volonterio, Alessandro,Bravo, Pierfrancesco,Zanda, Matteo
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p. 6537 - 6540
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by pyridinium hydrobromide perbromide
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The oxidation of benzaldehyde and 35 monosubstituted benzaldehydes by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each of the benzaldehydes and PHPB. Addition of pyridinium bromide has no effect on the rate of oxidation. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation whereas those of ortho-substituted benzaldehydes were correlated with a tetraparametric LDRS equation. The oxidations of para- and ortho-substituted benzaldehydes are more susceptible to the delocalization effect while the oxidation of meta-substituted compounds displays a greater dependence on the fi eld effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Aneja, Meenakshi,Kothari, Seema,Banerji, Kalyan K.
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p. 650 - 656
(2007/10/03)
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- Substituent effects on the base-catalysed hydrolysis of phenyl esters of ortho-substituted benzoic acids
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Fourteen model phenyl esters of 2-substituted benzoic acids were synthesised. Structures and purity of model compounds were confirmed by 1H and 13C NMR spectroscopy, as well as by HPLC and elemental analysis. Kinetics of base-catalysed hydrolysis of model phenyl esters occurring by the BAC2 mechanism were measured by UV spectrophotometry in 50% (v/v) aqueous dimethyl sulfoxide solutions at 25 °C under pseudo-first-order reaction conditions (c(NaOH) = 0.001-1.0 mol 1-1). Linear relation between JE- and log kobs with the slope close to unity was found for all model compounds. Neither one-parameter nor multiparameter Hammett-type description of variability of experimental data obtained for phenyl esters of 2-substituted benzoic acids was found. Two groups (conjugating and non-conjugating) were created by division of ortho-substituents in ortho-position using the AISE theory, based on their interaction with the reaction centre.
- Bauerova, Ingrid,Ludwig, Miroslav
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p. 770 - 784
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by hexamethylenetetramine-bromine
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The oxidation of thirty-six monosubstituted benzaldehydes by hexa-methylenetetramine-bromine (HABR), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to HABR. Michaelis-Menten-type kinetics were observed with respect to aldehyde. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of hexamethylenetetramine on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of γ suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Gangwani,Sharma,Banerji
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p. 615 - 622
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by benzyltrimethylammonium chlorobromate
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The oxidation of 35 monosubstituted benzaldehydes by benzyltrimethylammonium chlorobromate (BTMACB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both benzaldehyde and BTMACB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride or potassium bromide on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect, whereas the oxidation of ortho-and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Raju, V. Sitarama,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 3322 - 3325
(2007/10/03)
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- Dialkylhydrazides for directed orthometalations
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Dimethylhydrazides are shown to be excellent substrates for the directed orthometalation reaction. The advantage of using the hydrazide is that it is easily removed by treatment with H5IO6 or CuCl2 to give the carboxylic acid under very mild conditions, in contrast to other amides that generally require harshly acidic conditions to achieve hydrolysis. (C) 2000 Elsevier Science Ltd.
- Pratt, Scott A.,Goble, Michael P.,Mulvaney, Michael J.,Wuts, Peter G. M.
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p. 3559 - 3562
(2007/10/03)
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- Asymmetric oxidation catalyzed by myoglobin mutants
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The sperm whale myoglobin active site mutants (L29H/H64L and F43H/H64L Mb) have been shown to catalyze the asymmetric oxidation of sulfides and olefins. Thioanisole, ethyl phenyl sulfide, and cis-β-methylstyrene are oxidized by L29H/H64L Mb with more than
- Ozaki, Shin-Ichi,Yang, Hui-Jun,Matsui, Toshitaka,Goto, Yoshio,Watanabe, Yoshihito
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p. 183 - 192
(2007/10/03)
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- Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 12. Extrusion of Ph3P from sulfonyl ylides and reactivity of the resulting sulfonyl carbenes
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Twelve sulfonyl stabilised phosphorus ylides have been prepared and their behaviour upon flash vacuum pyrolysis at 600°C has been examined. Examples with an arylsulfonyl substituent undergo loss of Ph3PO to give intractable products but those with an arylmethylsulfonyl substituent separately lose Ph3P and SO2 to give products consistent with the intermediacy of sulfonyl carbenes. X-Ray structure determinations of one ylide from each series show a more significant P-O non-bonding interaction in the first case, providing some explanation for the different thermal reactivity.
- Aitken, R. Alan,Drysdale, Martin J.,Ferguson, George,Lough, Alan J.
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p. 875 - 880
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate
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The oxidation of 35 monosubstituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate (BBCP) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to BBCP. Michaelis - Menten-type kinetics were observed with respect to the aldehyde concentrations. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the four parametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho- and meta-substituted compounds which displays a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining activated complex. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Mohnot, Kavita,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 1310 - 1314
(2007/10/03)
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- Synthesis of pyrazolo[1,5-b][1,2]benzisothiazoles
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The synthesis of some pyrazolo[1,5-b] [1,2]benzisothiazoles is described. The route is based on the reaction between 3(5)-[2′-methylthiophenyl]pyrazoles and its derivatives with N-chlorosuccinimide.
- Moyroud, Joel,Chene, Alain,Guesnet, Jean-Luc,Mortier, Jacques
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p. 221 - 228
(2007/10/02)
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- The Reactions of Carbene Intermediates from the Reaction of Trialkyl Phosphites with Dialkyl Benzoylphosphonates: Intramolecular Cyclisations of 2-Substituted Dialkyl Benzoylphosphonates
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The reaction of dialkyl aroylphosphonates 1 with trialkyl phosphites leads to the formation of carbene intermediates 3 via the anionic intermediates 2.The carbene intermediates 3 (R = 2-Me, 2-Prn, 2-Bun, 2-MeS, 2-EtO and 2-EtS) have
- Griffiths, D. Vaughan,Griffiths, Penelope A.,Karim, Khalku,Whitehead, Belinda J.
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p. 901 - 925
(2007/10/03)
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- Directed lithiation of unprotected benzoic acids
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Benzoic acid gives the ortho-lithiated species 1 under standard conditions (s-BuLi-TMEDA-THF, -90 deg C).Reaction of 1 at -78 deg C with either methyl iodide, dimethyl disulfide, hexachloroethane, or 1,2-dibromotetrachloroethane gives the ortho-substituted product.Intramolecular competition between the carboxylic acid and methoxy, chloro, fluoro, or diethylamido functions in ortho- and -para-substituted benzoic acids establishes the carboxylic acid group to be of intermediate capacity in directing metallation.Complimentarity of directing effects is observed with the chloro and fluoro groups in the meta-substituted benzoic acid but not with the methoxy and trifluoromethyl groups.Electrophile introduction into meta- and para-lithiated benzoates occurs with equal efficacy and comparable scope.The 2,4-dihalogenobenzoic acids undergo hydrogen/metal exchange at the position flanked by both halogen substituents. 2,2-Difluoro-1,3-benzodioxole-4-carboxylic acid undergoes lithiation adjacent to the oxygen atom.By use of such methods, routes to benzoic acids contiguously tri- and tetra-substituted with a variety of functionalities have been developed.
- Bennetau, Bernard,Mortier, Jacques,Moyroud, Joel,Guesnet, Jean-Luc
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p. 1265 - 1272
(2007/10/02)
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- The Carboxylic Acid Group as an Effective Director of Ortho-Lithiation
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Treatment of PhCO2H in tetrahydrofuran with 2.2 equiv of a 1:1 sec-butyllithium/N,N,N',N'-tetramethyl-1,2-ethylenediamine complex at -90 deg C gave o-LiC6H4CO2Li, which was treated with electrophiles to give o-RC6H4CO2H (R = Me, SMe, Cl, Br) in good yields.
- Mortier, Jacques,Moyroud, Joeel,Bennetau, Bernard,Cain, Paul A.
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p. 4042 - 4044
(2007/10/02)
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- Alkylation Reactions by Means of Alkanols and Carbon Monoxide: An Efficient Synthesis of Thioethers and of Caffeine from Theophylline
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The reaction of sodium or potassium thiolates with alkanols and carbon monoxide provides a versatile route to produce thioethers in excellent yields.By analogy, the potassium salt of theophylline suffers a nearly quantitative conversion to caffeine when heated with methanol under CO pressure.The mechanism of these alkylation reactions is discussed. - Key Words: Nucleophilic alkylation / Thioethers / Caffeine / Carbon monoxide / Alkanols
- Bott, Kaspar
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p. 1955 - 1956
(2007/10/02)
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- Lipase-catalyzed kinetic resolution of a series of esters having a sulfoxide group as the stereogenic centre
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A series of methyl 2-(alkylsulfinyl)benzoates (alkyl = C1, n-C4, n-C8, n-C12 and n-C16) was investigated with respect to substrate behaviour and enantioselectivity in a lipase (Candida rugosa)-catalyz
- Allenmark,Andersson
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p. 2371 - 2376
(2007/10/02)
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- Separation of polar and steric effects in the oxidation of ortho-substituted benzaldehydes by ethyl chlorocarbamate
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Kinetics of oxidation of twelve ortho-substituted benzaldehydes by ethyl chlorocarbamate (ECC) to the corresponding benzoic acids have been studied.The reaction is first order each in , and +>.Addition of ethyl carbamate has no effect on the reaction rate. (EtOC(OH)NHCl)+ has been postulated as the reactive oxidizing species.The correlation of rates with single substituent parameter equations is poor.The correlation with Charton's eqution of inductive, resonance and steric parameters is satisfactory.However, excellent correlations are obtained, when Charton's steric parameter is used along with Taft's ?r and ?R+ substituent constants.The polar reaction constants have negative values.The reaction is subject to steric hindrance by the ortho-substituents.Mechanistic aspects are discussed.
- Varshney, Seema,Kothari, Seema,Banerji, Kalyan K.
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p. 205 - 209
(2007/10/02)
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- Correlation Analysis of the Reactivity in the Oxidation of Aromatic Aldehydes by N-Bromoacetamide
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The oxidation of thirty two para-, meta- and ortho-substituted benzaldehydes by N-bromoacetamide (NBA), to the corresponding benzoic acid, is first order with respect to the aldehyde, NBA and hydrogen ion.The oxidation of benzaldehyde exhibited a substantial primary kinetic isotope effect (kH/kD = 4.75).Addition of acetamide reduced the rate of oxidation.The postulated oxidising species is (H2OBr)+.The rates of the oxidation of the meta- and para-substituted aldehydes were separately correlated in Taft's and Swain's dual substituent parameter equations.For para-substituted aldehydes, the best correlation was obtained with ?I and ?R+ values, while the meta-substituted compounds correlated best with ?I and ?R0 values.The ortho-substituted aldehydes showed excellent correlation in a triparametric equation of Taft's ?I, ?R+ and Charton's steric parameters.The polar reaction constants have negative values.The reaction is subject to steric hindrance by the ortho-substituents.A mechanism involving transfer of a hydride from the aldehyde to the oxidant, in the rate-determining step, has been proposed.
- Gupta, Anita,Mathur, Sandhya,Banerji, Kalyan K.
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p. 201 - 223
(2007/10/02)
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