- Carbanion reactivity - σ-adduct formation and elimination in the reactions of the carbanion from bis(phenylsulfonyl)methane with 4-nitrobenzofurazan derivatives
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1H NMR studies in [2H6]-DMSO show that the carbanion. 4 from bis(phenylsulfonyl)methane reacts with 4,6- dinitrobenzofuroxan to yield a σ-adduct that undergoes base-catalysed elimination to yield an alkene derivative. Rate constants, measured spectrophotometrically, are reported for the corresponding reactions in methanol of 4 with 4-nitrobenzofurazan and some derivatives that give adducts at the 5-position. The intrinsic rate constant, ko, for this process has a value of 1.5±0.5. The 5-adducts undergo methoxide-catalysed elimination of phenylsulfinic acid to yield alkene derivatives and rate constants for this process are reported.
- Asghar, Basim H.M.,Crampton, Michael R.,Isanbor, Chukwuemeka
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Read Online
- Photoredox Catalyzed Sulfonylation of Multisubstituted Allenes with Ru(bpy)3Cl2 or Rhodamine B
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A highly regio- and stereoselective sulfonylation of allenes was developed that provided direct access to α, β-substituted unsaturated sulfone. By means of visible-light photoredox catalysis, the free radicals produced by p-toluenesulfonic acid reacted with multisubstituted allenes to obtain Markovnikov-type vinyl sulfones with Ru(bpy)3Cl2 or Rhodamine B as photocatalyst. The yield of this reaction could reach up to 91%. A series of unsaturated sulfones would be used for further transformation to some valuable compounds.
- Chen, Jingyun,Chen, Shufang,Jiang, Jun,Lu, Qianqian,Shi, Liyang,Xu, Zekun,Yimei, Zhao
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supporting information
(2021/11/09)
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- Abiological catalysis by myoglobin mutant with a genetically incorporated unnatural amino acid
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To inculcate biocatalytic activity in the oxygen-storage protein myoglobin (Mb), a genetically engineered myoglobin mutant H64DOPA (DOPA = L-3,4-dihydroxyphenylalanine) has been created. Incorporation of unnatural amino acids has already demonstrated their ability to accomplish many non-natural functions in proteins efficiently. Herein, the presence of redox-active DOPA residue in the active site of mutant Mb presumably stabilizes the compound I in the catalytic oxidation process by participating in an additional hydrogen bonding (H-bonding) as compared to the WT Mb. Specifically, a general acid-base catalytic pathway was achieved due to the availability of the hydroxyl moieties of DOPA. The reduction potential values of WT (E° = -260 mV) and mutant Mb (E° = -300 mV), w.r.t. Ag/AgCl reference electrode, in the presence of hydrogen peroxide, indicated an additional H-bonding in the mutant protein, which is responsible for the peroxidase activity of the mutant Mb. We observed that in the presence of 5 mM H2O2, H64DOPA Mb oxidizes thioanisole and benzaldehyde with a 10 and 54 folds higher rate, respectively, as opposed to WT Mb. Based on spectroscopic, kinetic, and electrochemical studies, we deduce that DOPA residue, when present within the distal pocket of mutant Mb, alone serves the role of His/Arg-pair of peroxidases.
- Chand, Subhash,Ray, Sriparna,Yadav, Poonam,Samanta, Susruta,Pierce, Brad S.,Perera, Roshan
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p. 1795 - 1808
(2021/05/21)
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- Visible-Light-Induced Radical Cascade Cyclizations of 1,7-Enynes with Sulfinic Acids: Direct Access to Sulfonated Chromanes and Sulfonated Tetrahydroquinolines under Metal-Free Conditions
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Visible-light-induced strategy to access sulfonated chromanes and sulfonated 1,2,3,4-tetrahydroquinolines via a radical cascade cyclization of 1-(arylethynyl)-2-(vinyloxy)benzenes and N-allyl-2-(arylethynyl)anilines with aromatic and aliphatic sulfinic acids has been developed. In the presence of TBHP (7.5 mol%) as an oxidant and Eosin Y (3.0 mol%) as a photocatalyst, the reactions undergo smoothly to afford the corresponding products in good yields at room temperature under metal-free conditions. This transformation features low loading of TBHP, mild reaction conditions, simple operation, broad functional-group tolerance, and good yields of products. (Figure presented.).
- Liu, Qi,Mei, Yousheng,Wang, Lei,Ma, Yongmin,Li, Pinhua
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supporting information
p. 5669 - 5680
(2020/10/28)
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- Photocatalytic α-Tertiary Amine Synthesis via C?H Alkylation of Unmasked Primary Amines
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A practical, catalytic entry to α,α,α-trisubstituted (α-tertiary) primary amines by C?H functionalisation has long been recognised as a critical gap in the synthetic toolbox. We report a simple and scalable solution to this problem that does not require any in situ protection of the amino group and proceeds with 100 percent atom-economy. Our strategy, which uses an organic photocatalyst in combination with azide ion as a hydrogen atom transfer (HAT) catalyst, provides a direct synthesis of α-tertiary amines, or their corresponding γ-lactams. We anticipate that this methodology will inspire new retrosynthetic disconnections for substituted amine derivatives in organic synthesis, and particularly for challenging α-tertiary primary amines.
- Alder, Catherine M.,Ballantyne, George,Cresswell, Alexander J.,Cunningham, William B.,Edwards, Lee J.,Grayson, Matthew N.,Kinsella, Anna G.,McKay, Blandine S. J.,Mules, Tom,Ryder, Alison S. H.,Turner-Dore, Jacob
-
supporting information
p. 14986 - 14991
(2020/06/20)
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- Insights into the electrochemical degradation of sulfamethoxazole and its metabolite by Ti/SnO2-Sb/Er-PbO2 anode
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Electrochemical degradation of sulfamethoxazole (SMX) and its metabolite acetyl-sulfamethoxazole (Ac-SMX) by Ti/SnO2-Sb/Er-PbO2 were investigated. Results indicated that the electrochemical degradation of SMX and Ac-SMX followed pseu
- Wang, Yanping,Zhou, Chengzhi,Wu, Jinhua,Niu, Junfeng
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supporting information
p. 2673 - 2677
(2020/06/01)
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- Synergistic combination of visible-light photo-catalytic electron and energy transfer facilitating multicomponent synthesis of β-functionalized α,α-diarylethylamines
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A synthetic strategy with the visible-light photo-catalytic synergistic combination of electron and energy transfer processes has been developed. The mild reaction conditions allow the radical-radical cross-coupling phenomenon for the multicomponent synthesis of β-arylsulfonyl(diarylphosphinoyl)-α,α-diarylethyl-amines from readily available arylsulfinic acids (diarylphosphine oxides), 1,1-diarylethylenes and arylazides.
- Wu, Yanan,Zhang, Yipin,Jiang, Mingjie,Dong, Xunqing,Jalani, Hitesh B.,Li, Guigen,Lu, Hongjian
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p. 6405 - 6408
(2019/06/07)
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- A Structural and Functional Model for the Tris-Histidine Motif in Cysteine Dioxygenase
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The iron(II) complexes [Fe(L)(MeCN)3](SO3CF3)2 (L are two derivatives of tris(2-pyridyl)-based ligands) have been synthesized as models for cysteine dioxygenase (CDO). The molecular structure of one of the complexes exhibits octahedral coordination geometry and the Fe?Npy bond lengths [1.953(4)–1.972(4) ?] are similar to those in the Cys-bound FeII-CDO; Fe?NHis: 1.893–2.199 ?. The iron(II) centers of the model complexes exhibit relatively high FeIII/II redox potentials (E1/2=0.988–1.380 V vs. ferrocene/ferrocenium electrode, Fc/Fc+), within the range for O2 activation and typical for the corresponding nonheme iron enzymes. The reaction of in situ generated [Fe(L)(MeCN)(SPh)]+ with excess O2 in acetonitrile (MeCN) yields selectively the doubly oxygenated phenylsulfinic acid product. Isotopic labeling studies using 18O2 confirm the incorporation of both oxygen atoms of O2 into the product. Kinetic and preliminary DFT studies reveal the involvement of an FeIII peroxido intermediate with a rhombic S= (Formula presented.) FeIII center (687–696 nm; g≈2.46–2.48, 2.13–2.15, 1.92–1.94), similar to the spectroscopic signature of the low-spin Cys-bound FeIIICDO (650 nm, g≈2.47, 2.29, 1.90). The proposed FeIII peroxido intermediates have been trapped, and the O?O stretching frequencies are in the expected range (approximately 920 and 820 cm?1 for the alkyl- and hydroperoxido species, respectively). The model complexes have a structure similar to that of the enzyme and structural aspects as well as the reactivity are discussed.
- Anandababu, Karunanithi,Ramasubramanian, Ramamoorthy,Wadepohl, Hubert,Comba, Peter,Johnee Britto, Neethinathan,Jaccob, Madhavan,Mayilmurugan, Ramasamy
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p. 9540 - 9547
(2019/07/04)
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- Allyl sulfone compound and preparation method and application thereof
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The invention discloses an allyl sulfone compound and a preparation method and application thereof. The preparation method comprises the following steps of sequentially adding allyl alcohol, sulfinicacid, palladium tetrakis(triphenylphosphine) and calcium bis(trifluoromethylsulfonyl)imide into a reaction solvent in an inert gas atmosphere, and carrying out a reaction under stirring for 12-48 h atthe temperature of 30 DEG C, wherein the equivalent ratio of allyl alcohol, sulfinic acid, palladiumtetrakis(triphenylphosphine) and calcium bis(trifluoromethylsulfonyl)imide is 1: (1.5-2): (1-3%): (5-10%); and removing the reaction solvent in the reaction liquid, and then performingpurifying to obtain the allyl sulfone compound. The preparation method disclosed by the invention is high in economy and wide in applicable substrate range; in addition, the obtained allyl sulfone compound has potential pharmaceutical activity and biological activity and is an important skeleton widely existing inbiologically and pharmaceutically active molecules.
- -
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Paragraph 0043-0048
(2020/01/12)
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- Reductive Cleavage of Secondary Sulfonamides: Converting Terminal Functional Groups into Versatile Synthetic Handles
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Sulfonamides are pervasive in pharmaceuticals and agrochemicals, yet they are typically considered as terminal functional groups rather than synthetic handles. To enable the general late-stage functionalization of secondary sulfonamides, we have developed a mild and general method to reductively cleave the N-S bonds of sulfonamides to generate sulfinates and amines, components which can further react in situ to access a variety of other medicinally relevant functional groups. The utility of this platform is highlighted by the selective manipulation of several complex bioactive molecules.
- Fier, Patrick S.,Kim, Suhong,Maloney, Kevin M.
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p. 18416 - 18420
(2019/11/20)
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- Direct Substitution of Secondary and Tertiary Alcohols to Generate Sulfones under Catalyst- and Additive-Free Conditions
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An environmentally benign protocol that affords propargylic sulfones containing highly congested carbon centers from easily accessible alcohols and sulfinic acids with water as the only byproduct is reported. The reaction proceeded via an in situ dehydrative cross-coupling process by taking advantage of the synergetic actions of multiple hydrogen bonds rather than relying on an external catalyst and/or additives to achieve high product distribution.
- Liu, Yanan,Xie, Peizhong,Sun, Zuolian,Wo, Xiangyang,Gao, Cuiqing,Fu, Weishan,Loh, Teck-Peng
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p. 5353 - 5356
(2018/09/13)
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- Total Synthesis, Stereochemical Assignment, and Divergent Enantioselective Enzymatic Recognition of Larreatricin
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A concise and efficient total synthesis of the lignan natural product larreatricin as well as an unambiguous assignment of configuration of its enantiomers are reported, resolving a long-held controversy. Enzyme kinetic studies revealed that different polyphenol oxidases show high and remarkably divergent enantioselective recognition of this secondary metabolite.
- Martin, Harry J.,Kampatsikas, Ioannis,Oost, Rik,Pretzler, Matthias,Al-Sayed, Emir,Roller, Alexander,Giester, Gerald,Rompel, Annette,Maulide, Nuno
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supporting information
p. 15756 - 15760
(2018/10/09)
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- Visible-Light Photoredox Catalyzed Oxidative/Reductive Cyclization Reaction of N-Cyanamide Alkenes for the Synthesis of Sulfonated Quinazolinones
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An efficient photocatalytic oxidative/reductive cyclization reaction of N-cyanamide alkenes with arylsulfinic acids or arylsulfonyl chlorides, which proceeds through C-S, C-C, and C-N bond formations, is reported. This photocatalytic reaction was carried out under mild conditions, which provides a new strategy for the synthesis of sulfonated quinazolinones. Furthermore, a one-pot procedure to achieve terminal alkenes has been explored via elimination of the obtained sulfonated quinazolinones under basic conditions.
- Qian, Ping,Deng, Yu,Mei, Haibo,Han, Jianlin,Zhou, Jie,Pan, Yi
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supporting information
p. 4798 - 4801
(2017/09/23)
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- Visible-Light Photocatalytic Bicyclization of 1,7-Enynes toward Functionalized Sulfone-Containing Benzo[a]fluoren-5-ones
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A new visible-light photocatalytic arylsulfonylation and bicyclization of C(sp3)-tethered 1,7-enynes with sulfinic acids has been developed, delivering functionalized sulfone-containing benzo[a]fluoren-5-ones with generally good yields. This Eosin Y-catalyzed approach makes use of visible light as a safe and eco-friendly energy source to drive cascade cyclization reactions, resulting in continuous multiple bond-forming events including C–S and C–C bonds to efficiently construct polycyclic-linked alkyl aryl sulfones. (Figure presented.).
- Huang, Min-Hua,Zhu, Yi-Long,Hao, Wen-Juan,Wang, Ai-Fang,Wang, De-Cai,Liu, Feng,Wei, Ping,Tu, Shu-Jiang,Jiang, Bo
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supporting information
p. 2229 - 2234
(2017/07/07)
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- Method for synthesizing aryl sulfonic acid by utilizing sulfur dioxide
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The invention relates to a method for synthesizing aryl sulfonic acid by utilizing sulfur dioxide. The method is characterized by comprising the following steps that S1, aromatic hydrocarbon is added into a solvent, stirring is performed to achieve complete dissolution, and then a catalyst is added; S2, under the stirring condition and the conditions of 0-100 DEG C and 0-10 atm, dried excessive sulfur dioxide gas or sulfur dioxide liquid are added, and reaction is performed for 0.5-50 hours; S3, the reaction liquid obtained in the step S2 is cooled to 10 DEG C or below, pressurized filtration is performed, and a catalyst is recovered; S4, filtrate is distilled to recover unreacted sulfur dioxide, then the solvent is recovered through distillation, the residual solid is the product aryl sulfonic acid, and the product yield is higher than 85%. The raw materials for the method for synthesizing the aryl sulfonic acid by utilizing the sulfur dioxide are cheap and easy to obtain, the product yield is high, the production process is safer, ad the severe environmental pollution of a traditional process is greatly reduced.
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Paragraph 0030-0035; 0054-0059
(2018/01/04)
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- Direct Irradiaton of Aryl Sulfides: Homolytic Fragmentation and Sensitized S-Oxidation
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The direct irradiation of diphenyl sulfide and p-substituted thioanisoles in the presence of oxygen was investigated by means of both steady state and laser flash photolysis experiments. Two competitive pathways took place from the triplet excited state o
- Bonesi, Sergio M.,Crespi, Stefano,Merli, Daniele,Manet, Ilse,Albini, Angelo
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p. 9054 - 9065
(2017/09/11)
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- A General, One-Pot Method for the Synthesis of Sulfinic Acids from Methyl Sulfones
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A simple and efficient method for converting methyl sulfones to sulfinic acids is described. The process involves alkylation with a benzylic halide, followed by in situ elimination of the resulting styrene in the presence of excess base to yield a sulfinic acid in a single reaction process. The usefulness of the alkylation-elimination sequence is demonstrated by generating a variety of sulfinic acids from methyl sulfones. Late stage functionalization and 14C-labeling of several biologically active methyl sulfones were accessed via sulfinate intermediates.
- Gauthier, Donald R.,Yoshikawa, Naoki
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supporting information
p. 5994 - 5997
(2016/12/09)
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- Consecutive visible-light photoredox decarboxylative couplings of adipic acid active esters with alkynyl sulfones leading to cyclic compounds
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Novel and efficient consecutive photoredox decarboxylative couplings of adipic acid active esters (bis(1,3-dioxoisoindolin-2-yl)-substituted hexanedioates) with substituted 1-(2-arylethynylsulfonyl)benzenes have been developed under visible-light photocatalysis. The successive photoredox decarboxylative C-C bond formation at room temperature afforded the corresponding cyclic compounds in good yields with tolerance of some functional groups.
- Li, Jingjing,Tian, Hua,Jiang, Min,Yang, Haijun,Zhao, Yufen,Fu, Hua
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p. 8862 - 8864
(2016/07/22)
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- Highly selective pd-catalyzed intermolecular fluorosulfonylation of styrenes
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A novel Pd-catalyzed intermolecular regio- and diastereoselective fluorosulfonylation of styrenes has been developed under mild conditions. This reaction exhibits a wide range of functional-group tolerance in styrenes and arylsulfinic acids to afford various β-fluoro sulfones. Preliminary mechanistic study reveals an unusual mechanism, in which a high-valent L2PdIIIF species side-selectively reacts with a benzylic carbon radical to deliver a C-F bond. This pathway is distinct from a previously reported radical fluorination reaction.
- Yuan, Zheliang,Wang, Hao-Yang,Mu, Xin,Chen, Pinhong,Guo, Yin-Long,Liu, Guosheng
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supporting information
p. 2468 - 2471
(2015/03/04)
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- Thermal oxidation to regenerate sulfone poisoned Pd-based catalyst: Effect of the valence of sulfur
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Sulfur deactivation is a serious problem which largely limits the industrial application of noble metals as catalysts. Here we report a thermal oxidation method to regenerate sulfone poisoned Pd/C catalyst applied in the hydrogenation of sodium-m-nitrobenzene sulfonate (SNS). It was found that the initial activity of Pd/C catalyst could be substantially recovered after treating it in air at temperatures as low as 100 °C. And the catalyst could be reused for at least 20 times without the significant loss of activity. The properties of deactivated and regenerated catalysts were studied in detail by BET measurement, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD), and Fourier transform infrared spectroscopy (FT-IR). The results indicated that the main surface sulfur species found on deactivated and regenerated Pd surfaces were Sn and sulfate (SO4), respectively. The change of the valence of sulfur species was found to be the key factor influencing the catalytic activity of the Pd-based catalyst. the Partner Organisations 2014.
- Xu, Tieyong,Zhang, Qunfeng,Jiang, Dahao,Liang, Qiuxia,Lu, Chunshan,Cen, Jie,Li, Xiaonian
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p. 33347 - 33354
(2014/08/18)
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- Copper-mediated cascade synthesis of diaryl sulfones via the sandmeyer reaction
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A convenient and efficient method for the copper-mediated cascade synthesis of diaryl sulfones via the Sandmeyer reaction has been developed. The protocol uses readily available aryl amines and arylsulfinic acids as the starting materials, isoamyl nitrite as the diazotizating reagent of the aryl amines, and the method shows mild reaction conditions and high tolerance towards various functional groups in the substrates. Georg Thieme Verlag Stuttgart New York.
- Yang, Xiaobo,Shi, Liangliang,Fu, Hua
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supporting information
p. 847 - 852
(2014/04/17)
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- Three-component reactions of ketene dithioacetals, aldehydes, and arenesulfinic acids: Facile synthesis of allylic sulfones
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A facile and efficient synthesis of allylic sulfones via sulfuric acid-mediated three-component reactions of easily available ketene dithioacetals, aldehydes, and arenesulfinic acids is presented. The reaction features low cost and good yields.
- Liang, Deqiang,Huang, Wenzhong,Yuan, Lin,Ma, Yinhai,Ouyang, Liping,Rao, Yuqin,Yang, Yuxian
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supporting information
p. 1930 - 1937
(2014/07/07)
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- Microwave-accelerated Pd-catalyzed desulfitative direct C2-arylation of free (NH)-indoles with arylsulfinic acids
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The rapid and efficient direct C2-arylation of free (NH)-indoles with arylsulfinic acids proceeded through a microwave-accelerated palladium-catalyzed desulfitation reaction. By using PdCl2 as a catalyst, silver acetate as an oxidant, and H2SO4 as an additive, arylsulfinic acids with both electron-donating and electron-withdrawing groups underwent desulfitative coupling with an array of free (NH)-indoles, thereby selectively providing C2-arylindoles in good yields. From C2 shining sea: The direct C2-arylation of free (NH)-indoles with arylsulfinic acids proceeded through a Pd-catalyzed desulfitation reaction. In the presence of an oxidant and an additive, 2-arylindoles were selectively afforded in good yields. Copyright
- Miao, Tao,Li, Pinhua,Wang, Guan-Wu,Wang, Lei
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p. 3185 - 3190
(2014/01/06)
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- One-step synthesis of racemic α-amino acids from aldehydes, amine components, and gaseous CO2 by the aid of a bismetal reagent
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α-Amino acids are essential resources for human life and are highly useful as building blocks for organic synthesis. The core framework of an α-amino acid can be divided into three basic components: an aldehyde, an amine, and carbon dioxide (CO2). We report herein that a one-step synthesis of α-amino acids has been successfully achieved from these three basic and inexpensive chemicals with a single operation, in which the mixture of an aldehyde, a sulfonamide, and gaseous CO2 was heated at 100 °C in the presence of Bu3Sn-SnBu3 and CsF. In this one-pot sequential protocol, two important intermediates (imine and α-amino stannane) are involved and the stannyl anion generated in situ plays a crucial role, particularly for the efficient stannylation of the imine in the presence of proton sources and for promoting retrostannylation of the undesired α-alkoxy stannane owing to its high stability and tolerance of the presence of proton sources. This methodology enabled the synthesis of a wide range of racemic arylglycine derivatives in high yields. Go retro! α-Amino acids are essential resources for human life and are highly useful as building blocks for organic synthesis. The core framework of an α-amino acid is retrosynthesized to an aldehyde, an amine, and carbon dioxide. A one-step synthesis of α-amin Copyright
- Mita, Tsuyoshi,Higuchi, Yuki,Sato, Yoshihiro
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p. 1123 - 1128
(2013/02/23)
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- DNA-based asymmetric organometallic catalysis in water
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Here, the first examples of DNA-based organometallic catalysis in water that give rise to high enantioselectivities are described. Copper complexes of strongly intercalating ligands were found to enable the asymmetric intramolecular cyclopropanation of α-diazo-β-keto sulfones in water. Up to 84% ee was achieved, in the presence of salmon testes DNA as the only source of chirality, using dipyrido[3,2-a:2′,3′-c]phenazine (dppz) derivatives as ligands.
- Oelerich, Jens,Roelfes, Gerard
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p. 2013 - 2017
(2013/08/25)
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- O-Substituted N-oxy arylsulfinamides and sulfonamides in Michael reactions
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O-Substituted N-oxy arylsulfinamides and sulfonamides undergo fast aza-Michael reaction in the presence of base and electron-deficient α,β-unsaturated olefins under mild conditions. With N-silyloxy benzenesulfinamides, no aza-Michael product is observed and a hetero aza-Brook type rearrangement takes place induced by the base. Room temperature N-desulfinylation of N-benzyloxybenzenesulfinamide is achieved using BF 3.Et2O. N-Alkoxy arylsulfonamides aza-Michael adducts are found to be generally highly stable under strongly acidic and basic conditions.
- Bonifacio, Vasco D. B.,Kumar, Rakesh P.,Prabhakar, Sundaresan,Lobo, Ana M.
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p. 266 - 276
(2011/11/06)
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- An efficient, multiply promiscuous hydrolase in the alkaline phosphatase superfamily
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We report a catalytically promiscuous enzyme able to efficiently promote the hydrolysis of six different substrate classes. Originally assigned as a phosphonate monoester hydrolase (PMH) this enzyme exhibits substantial second-order rate accelerations ((kcat/KM) /k w), ranging from 107 to as high as 1019, for the hydrolyses of phosphate mono-, di-, and triesters, phosphonate monoesters, sulfate monoesters, and sulfonate monoesters. This substrate collection encompasses a range of substrate charges between 0 and -2, transition states of a different nature, and involves attack at two different reaction centers (P and S). Intrinsic reactivities (half-lives) range from 200 days to 105 years under near neutrality. The substantial rate accelerations for a set of relatively difficult reactions suggest that efficient catalysis is not necessarily limited to efficient stabilization of just one transition state. The crystal structure of PMH identifies it as a member of the alkaline phosphatase superfamily. PMH encompasses four of the native activities previously observed in this superfamily and extends its repertoire by two further activities, one of which, sulfonate monoesterase, has not been observed previously for a natural enzyme. PMH is thus one of the most promiscuous hydrolases described to date. The functional links between superfamily activities can be presumed to have played a role in functional evolution by gene duplication.
- Van Loo, Bert,Jonas, Stefanie,Babtie, Ann C.,Benjdia, Alhosna,Berteau, Olivier,Hyvoenen, Marko,Hollfelder, Florian
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scheme or table
p. 2740 - 2745
(2010/10/03)
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- Catalyst-free alkylation of sulfinic acids with sulfonamides via sp 3 C-N bond cleavage at room temperature
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An unprecedented catalyst-free alkylation of sulfinic acids with sulfonamides has been developed via sp3 C-N bond cleavage at room temperature. In the absence of external catalysts and additives, a wide variety of N-benzylic and N-allylic sulfonamides couple with sulfinic acids to give structurally diversified sulfones in moderate to excellent yields. Furthermore, the reaction of N-(2-acyl)allylic sulfonamides with sulfinic acids provides a convenient access to trisubstituted allyl sulfones with exclusive Z selectivity.
- Liu, Cong-Rong,Li, Man-Bo,Cheng, Dao-Juan,Yang, Cui-Feng,Tian, Shi-Kai
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supporting information; experimental part
p. 2543 - 2545
(2009/10/10)
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- Addition reactions of benzenesulfinic acid with glycals and 1,2-dibromosugars
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The addition of benzenesulfinic acid to glycals was investigated under various conditions, and optimized yields of the glycosyl phenylsulfone products were obtained in the presence of tin tetrachloride as a catalyst. Double bond shift (Ferrier rearrangement) occurred in all cases except amicetal, which lacks a substituent at the allylic carbon. Glycosylation of benzenesulfinic acid with 1,2-dibromides was carried out using silver triflate as the promoter, and gave sulfinate esters as products by reaction at oxygen rather than at sulfur. The sulfinate esters were obtained as mixtures of stereoisomers at the stereogenic sulfur atom. Trapping of the sulfinates with carboxylate nucleophiles was observed during attempted oxidation with MCPBA. Copyright Taylor & Francis Group, LLC.
- Basava, Vikram,Flores, Broc,Giovine, Matthew,Licisyn, Thomas,Walck, Katelyn,Boyko, Walter,Giuliano, Robert
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experimental part
p. 389 - 400
(2009/04/11)
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- Hydrolysis rates of alkyl and aryl sulfinamides: evidence of general acid catalysis
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Sulfinamides are important in enantioselective synthesis, as rare post-translational modifications of proteins and as isosteres of the amide bond. Little is known about the rates of hydrolysis for aliphatic sulfinamides or the mechanism of hydrolysis. In this Letter, we show that sulfinamides hydrolyse by predominantly a non-specific acid/base catalysis with phosphate buffer but by varying the buffer concentration, it was possible to determine the hydrolysis rates of a range of sulfinamides with water through non-linear least squares regression.
- Piggott, Andrew M.,Karuso, Peter
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p. 7452 - 7455
(2008/03/13)
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- Kinetics and mechanisms of the acid-catalyzed hydrolyses of N-(4-substituted-arylsulfinyl)phthalimides
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The acid-catalyzed hydrolyses of N-(4-substituted-arylsulfinyl)phthalimides were studied in aqueous solutions of perchloric and sulfuric acids at 50.0 ± 0.1 and of hydrochloric acid at 40.0 ± 0.1°C. Analysis of the data by the Cox-Yates excess acidity method and substituent, temperature and solvent isotope effects indicate hydrolysis by an A2 mechanism at low acidity. At higher acidities a changeover to an A1 mechanism is observed. Copyright
- Kutuk, Halil,Bekdemir, Yunus,Soydas, Yasemin
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p. 224 - 228
(2007/10/03)
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- Substituted oxygen alicyclic compounds, including methods for synthesis thereof
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The invention provides new methods for preparation of cyclic oxygen compounds, including 2,5-disubstituted tetahydrofurans, 2,6-disubstituted tetrahydropyrans, 2,7-disubstituted oxepanes and 2,8-oxocanes. The invention also provides new cyclic oxygen compounds and pharmaceutical compositions and therapeutic methods that comprise such compounds.
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- The anionic route to tricyclanes
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A very mild anion induced intramolecular ring closure route to tricyclanes is reported. (C) 2000 Elsevier Science Ltd.
- Afarinkia, Kamyar,Mahmood, Farzana
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p. 1287 - 1290
(2007/10/03)
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- Buffer Catalysis of the Hydrolysis of Phenyl and Methyl Benzenesulfinates. Contrasting Behavior between Acyclic and Cyclic Analogs
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The hydrolysis of phenyl benzenesulfinate is catalyzed by both acid and base, and is strongly accelerated by the carboxylate and amine base components of the buffer. Carboxylates and amines constitute different groups in the Bronsted plots, falling nearly on two separate lines of β=1. The carboxylates are about 400-times more effective catalysts than the amines of similar basicity. Solvent deuterium isotope effects on the catalytic constants are small, and the buffer catalysis is considered to be nucleophilic. By contrast, the hydrolysis of the methyl ester was only weakly affected by the buffer, if at all. High efficiencies of oxygen nucleophiles in the catalysis of the hydrolysis of acyclic sulfinates are distinctive compared with the cyclic analogs, and are rationalized by a concerted SN2-like mechanism of the nucleophilic reaction at sulfur.
- Okuyama, Tadashi
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p. 3281 - 3287
(2007/10/03)
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- Unexpected deoxygenation of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) by thiyl radicals through the formation of arylsulphinyl radicals
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2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), upon reaction with thiophenols, undergoes deoxygenation leading mainly to the formation of tetramethylpiperidinium arylsulphinates and arylsulphonates. Other identified products of the reaction are aryldisulphides, 2,2,6,6-tetramethylpiperidine, S-aryl-arylthiosulphonates, N-arylsulphinyl- and N-arylsulphonyl-2,2,6,6-tetramethylpiperidine. The formation of the reaction products is discussed on the basis of the interaction of arylsulphinyl and arylsulphonyl radicals with TEMPO as well as on the basis of the evolution of the arylsulphinyl radical itself.
- Carloni,Carloni, Patricia,Damiani,Damiani, Elisabetta,Iacussi,Iacussi, Marco,Greci,Greci, Lucedio,Stipa,Stipa, Pierluigi,Cauzi,Cauzi, Daniele,Rizzoli,Rizzoli, Corrado,Sgarabotto,Sgarabotto, Paolo
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p. 12445 - 12452
(2007/10/02)
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- Kinetics of the Reaction of 2,4-Dinitrophenyl-4'-substituted Phenyl Sulfones with Morpholine in Methanol
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The rates of morpholine-desulfonylation of 2,4-dinitrophenyl-4'-substituted phenylsulfones (1-6: aryl = 4-Y-C6H4, Y = H, CH3, OCH3, Br, Cl and NO2) have been measured in methanol at different temperatures (25 deg C-40 deg C) and the activation parameters were calculated.A good Hammett correlation was obtained with ρ values of 0.43-0.75.The plot ΔH(excit.) versus ΔS(excit.) gave an isokinetic temperature at 339 deg K.
- El-Mallah, Nabila M.,Hamed, E. A.,El-Bardan, A. A.
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p. 319 - 328
(2007/10/03)
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- A General Synthesis of Aromatic Compounds Carrying Two Neopentyl Groups on Adjacent Positions
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3,4-Dineopentylthiophene (4) was synthesized in a good overall yield starting frm methyl neopentyl ketone. 3,4-Dineopentylthiophene-1,1-dioxide (5a), easily obtainable by oxidation of 4, undergoes Diels-Alder reactions with a variety of acetylenic dienophiles or their equivalent to furnish aromatic compounds carrying two neopentyl groups on adjacent positions.
- Nakayama, Juzo,Yoshimura, Koichi
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p. 2709 - 2712
(2007/10/02)
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- SYNTHESIS, SPECTRAL STUDIES AND C-S BOND FISSION OF SOME NOVEL ALKYL -3-NITROBENZOATES AND THEIR SULFINYL DERIVATIVES
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Methyl and ethyl-4--3-nitrobenzoates and the corresponding sulfinyl derivatives have been synthesized.The structure of these esters were proved by IR, NMR and mass spectra.A linear relationship between δ-ppm values of the benzylic protons and ?-Hammett values of the 4'-substituents has been found.The carbon-sulfur bond fission with 5percent sodium hydroxide solution in addition to the alkaline ester hydrolysis is discussed. Key words: Arylsulfonyl; arylsulfinyl nitrobenzoate; NMR; mass spectra; C-S bond fission.
- El-Bardan, Ali A.
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p. 153 - 164
(2007/10/02)
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- Convenient methods for the preparation of sulfur substituted allenecarboxylates
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2-Sulfinyl- and 2-sulfonylallenecarboxylates, as new 1,1-diacceptor substituted allenes, were prepared starting from methyl 4-hydroxy-4-methyl-2-pentynoate by a [2,3]-sigmatropic rearrangement. The sulfoxides could be reduced to the corresponding allenyl sulfides. A 2(5H)-furanone derivative was prepared by a side-reaction.
- Conrads,Mattay
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- Rate-limiting deprotonation of (arylsulfonyl)methyl perchlorates in dichloromethane. Evidence for proton tunneling and the high dynamic basicity of HMPA in a nonaqueous solvent
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Kinetic data are reported for the water-catalyzed hydrolysis of several (arylsulfonyl)methyl perchlorates in water and for the HMPA-catalyzed decomposition of the same substrates in dichloromethane.Under both conditions, the reaction exhibits general base catalysis and the covalent perchlorates react via rate-limiting deprotonation at the α-sulfonyl methylene moiety.Primary kinetic deuterium isotope effects (KDIE's) in water are indicative for a complete loss of zero-point energy in the transition state.The high symmetry of the transition state is supported by theBroensted β value of ca. 0.5.HMPA was found to be an effective general base catalyst in dichloromethane as the solvent.This reaction shows primary KDIE's (kH/kD = 9.3 at 25 deg C) which are about 1.5 times higher than the (semi)classical limit.In addition, the ratio of the pre-exponential Arrhenius factors is abnormally small (AH/AD = 0.14).These classically anomalous results are interpreted in terms of a contribution of quantum-mechanical tunneling to the transition state for HMPA-induced deprotonation.Possible reasons for the different kinetic characteristics of the deprotonation reaction in the aqueous and nonaqueous medium are given.
- Andel, Maarten A. van,Engberts, Jan B. F. N.
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p. 204 - 207
(2007/10/02)
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- A Novel Synthesis of Aromatic Sulfinic Acids
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Aromatic sulfinic acids were synthesized conveniently by the direct oxidation of thiols with 30percent aqueous hydrogen peroxide at room temperature in good yield.Keywords - oxidation; thiol; sulfinic acid; benzene sulfinic acid; hydrogen peroxide.
- Kamiyama, Tsutomu,Enomoto, Saburo,Inoue, Masami
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p. 2652 - 2653
(2007/10/02)
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- Elimination and Addition Reactions. Part 41. Nucleophilic Eliminative Fission of Cyclopropanes: the Coiled Spring Effect of Ring Strain on Nucleofugality and its Evaluation
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Rates have been measured of sulphonyl-activated eliminative ring fissions of a series of six cyclopropanes in which the leaving group is stabilised by alkoxycarbonyl, cyano, or sulphonyl groups.The measurements allow assignment of ranks (nucleofugalities) to carbon leaving groups in systems in which the connection to the leaving group is strained by incorporation in a cyclopropane ring.The values obtained are compered with those obtained for a unstrained (acyclic) analogues.Rank enhancements of about 9(log) units are obtained; these enhancements suggests that free energies of activation for leaving-group expulsion are reduced by about 53 kJmol-1, or about 46 percent of these excess of enthalpy of the strained ring, notwithstanding the small degree of ring fission in the transition structure.The effect of phenyl substitution at the leaving group suggests that cleavage of the ring is very little advanced in the transition structure, although this is variable with the nature of the leaving-group stabilisation.This is the first direct determination of the effect of strain on nucleofugality.
- Hughes, Simon,Griffiths, Gwerydd,Stirling, Charles J. M.
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p. 1253 - 1264
(2007/10/02)
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- PREPARATION OF SPIROKETALS BY REACTION OF ANIONS FROM 2-BENZENESULPHONYLTETRAHYDROPYRANS WITH EPOXIDES:SYNTHESIS OF THE C-11 TO C-25 FRAGMENT OF THE MILBEMYCINS
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Deprotonation of 2-benzenesulphonyltetrahydropyrans with n-butyllithium affords anions which react with substituted epoxides to give spiroketals upon acidification.Using this approach a highly convergent synthesis of the C-11 to C-25 fragment of the milbemycins was achieved.
- Greck, Christine,Grice, Peter,Ley, Steven V.,Wonnacott, Anne
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p. 5277 - 5280
(2007/10/02)
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- Nickel- and Palladium-Catalyzed Additions of Nucleophiles to Cyclic 1,3-Dienes
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Carbon nucleophiles have been found to add smoothly to 1,3-cyclohexadiene using either a preformed nickel-ligand complex or Ni(0) prepared by in situ reduction of Ni(II) in the presence of a ligand to give 1,2- and 1,4-addition products.Analogous adducts were also obtained from 1,3-cyclopentadiene and 1,3-cyclooctadiene, but the yields were considerably lower.Attempts to add benzenesufinic acid to 1,3-cyclohexadiene using Ni(0) were unsuccessful; this reaction was instead found to be catalyzed by Pd(0)-phosphite complexes.
- Andell, Ove S.,Baeckvall, Jan-E.,Moberg, Christina
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p. 184 - 189
(2007/10/02)
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- ELIMINATION AND ADDITION REACTIONS. PART 39. VARIATION OF NUCLEOFUGALITY WITH TRANSITION STATE STRUCTURE-1,3- AND 1,2-ELIMINATIONS FROM CARBANIONS COMPARED.
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Phenylsulphonyl-activated 1,3-eliminations have been investigated with the objective of determining nucleofugalities of six leaving groups.In cyclohexane-1,3-diyl and propane-1,3-diyl system unactivated 1,2-elimination of 'poor' leaving groups occurs faster than 1,3-elimination.In 2,2-dimethylpropane-1,3-diyl substrates, however, quantitative 1,3-eliminations occur and the nucleofugalities of Br, Cl, OTs, PhSO2, PhS, PhO, have been determined.In a linear free energy relationship extending over 15 pKa units and 12 rank units, an excellent correlation of nucleofugality with the pKa of the conjugate acid of the leaving group is found.It is concluded from the comparison with 1,2-eliminations previously studied that 1,3-elimination involves considerable leaving group separation and ring formation in the transition state.With bromide as leaving group, the 2,2-dimethylpropane-1,3-diyl system is 1000 times more reactive in cyclopropane formation than the propane-1,3-diyl system; this is the first quantitation of the Thorpe-Ingold effect in homocyclic ring formation.With chloride and tosylate leaving groups, smaller accelerations are observed.
- Issari, Bahram,Stirling, Charles J. M.
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p. 1043 - 1052
(2007/10/02)
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