- Clean protocol for deoxygenation of epoxides to alkenes: Via catalytic hydrogenation using gold
-
The epoxidation of olefin as a strategy to protect carbon-carbon double bonds is a well-known procedure in organic synthesis, however the reverse reaction, deprotection/deoxygenation of epoxides is much less developed, despite its potential utility for the synthesis of substituted olefins. Here, we disclose a clean protocol for the selective deprotection of epoxides, by combining commercially available organophosphorus ligands and gold nanoparticles (Au NP). Besides being successfully applied in the deoxygenation of epoxides, the discovered catalytic system also enables the selective reduction N-oxides and sulfoxides using molecular hydrogen as reductant. The Au NP catalyst combined with triethylphosphite P(OEt)3 is remarkably more reactive than solely Au NPs. The method is not only a complementary Au-catalyzed reductive reaction under mild conditions, but also an effective procedure for selective reductions of a wide range of valuable molecules that would be either synthetically inconvenient or even difficult to access by alternative synthetic protocols or by using classical transition metal catalysts. This journal is
- Fiorio, Jhonatan L.,Rossi, Liane M.
-
p. 312 - 318
(2021/01/29)
-
- Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale
-
A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log KB=LAB+LBB allows equilibrium constants, KB, to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LAB) and one for Lewis basicity (LBB). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical–organic descriptors and known thermodynamic data (ΔH (Formula presented.)). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.
- Mayer, Robert J.,Hampel, Nathalie,Ofial, Armin R.
-
supporting information
p. 4070 - 4080
(2021/01/29)
-
- Photorelease of Pyridines Using a Metal-Free Photoremovable Protecting Group
-
The photorelease of bioactive molecules has emerged as a valuable tool in biochemistry. Nevertheless, many important bioactive molecules, such as pyridine derivatives, cannot benefit from currently available organic photoremovable protecting groups (PPGs). We found that the inefficient photorelease of pyridines is attributed to intramolecular photoinduced electron transfer (PET) from PPGs to pyridinium ions. To alleviate PET, we rationally designed a strategy to drive the excited state of PPG from S1 to T1 with a heavy atom, and synthesized a new PPG by substitution of the H atom at the 3-position of 7-dietheylamino-coumarin-4-methyl (DEACM) with Br or I. This resulted in an improved photolytic efficiency of the pyridinium ion by hundreds-fold in aqueous solution. The PPG can be applied to various pyridine derivatives. The successful photorelease of a microtubule inhibitor, indibulin, in living cells was demonstrated for the potential application of this strategy in biochemical research.
- Dong, Zaizai,Fang, Xiaohong,Kou, Xiaolong,Tan, Weihong,Tang, Xiao-Jun,Wu, Yayun,Zhang, Zhen,Zhao, Rong,Zhou, Wei
-
supporting information
p. 18386 - 18389
(2020/08/24)
-
- Axial coordination reactions with nitrogenous bases and determination of equilibrium constants for zinc tetraarylporphyrins containing four β, β ′-fused butano and benzo groups in nonaqueous media
-
The axial coordination properties of six zinc tetraarylporphyrins with seven different nitrogenous bases were examined in CH2Cl2 for derivatives containing four β,β′-fused butano or benzo groups and the equilibrium constants (logK) determined using spectral titration methods. The examined compounds are represented as butano(YPh)4PorZn and benzo(YPh)4PorZn, where Por is the porphyrin dianion and Y is a CH3, H or Cl substituent on the para-position of each meso-phenyl ring of the macrocycle. The initial four-coordinate butano-And benzoporphyrins will axially bind one nitrogenous base to form five-coordinate derivatives in CH2Cl2 and this leads to a 4-22 nm red-shift of the Soret and Q bands. The logK values range from 1.98 to 4.69 for butano(YPh)4PorZn and from 3.42 to 5.36 for benzo(YPh)4PorZn, with the exact value depending upon the meso and β-substituents of the porphyrin and the conjugate acid dissociation constants (pKa) of the nitrogenous base.
- Ye, Lina,Fang, Yuanyuan,Ou, Zhongping,Wang, Liping,Xue, Songlin,Lu, Yang,Kadish, Karl M.
-
p. 196 - 206
(2019/02/19)
-
- HOMOGENEOUS PROCESS FOR HYDRODEHALOGENATING HALOGENATED HETEROARYL COMPOUNDS
-
The present invention provides a homogeneous process for hydrodehalogenating a halo-substituted C3-C20 heteroaryl starting material to form a non-halogenated C3-C20 heteroaryl product and/or a halo- substituted C3-C20 heteroaryl product, wherein the halo-substituted C3-C20 heteroaryl product has at least one less halogen substituents than the halo-substituted C3-C20 heteroaryl starting material, the process comprising the step of hydrogenating the halo-substituted C3-C20 heteroaryl starting material in the presence of a rhodium or ruthenium complex, molecular hydrogen, a base and a solvent, wherein the process is carried out in a monophasic solvent system and the molar ratio of base to each halogen substituent to be removed is at least 1 :1.
- -
-
Page/Page column 11-12
(2017/07/11)
-
- Glycinatocopper(II) complex as an efficient heterogeneous catalyst for aromatic Finkelstein reaction of aryl and heteroaryl bromides to chlorides
-
Glycinatocopper(II) complex 1, readily synthesized from copper chloride and glycine was characterized by various techniques including FTIR, XRD, TGA and SEM analysis. The as-synthesized copper complex was found to be a simple and efficient catalyst for the synthesis of aryl and heteroaryl chlorides via aromatic Finkelstein reaction of aryl and heteroaryl bromides in high to excellent yields. The developed glycinatocopper(II) catalyst could easily be recovered from the reaction mixture and reused successfully for several runs without any loss in catalytic efficiency. The developed methodology represents the first example of the use of heterogeneous catalyst for the synthesis of aryl and heteroaryl chlorides via aromatic Finkelstein reaction.
- Verma, Sanny,Saran, Sandeep,Jain, Suman L.
-
p. 178 - 183
(2014/02/14)
-
- Iron(III)-mediated photocatalytic selective substitution of aryl bromine by chlorine with high chloride utilization efficiency
-
An iron(III)-mediated photocatalytic method for the conversion of aryl, heteroaryl and polycyclic aromatic bromides to the corresponding chlorides with high selectivity has been achieved successfully. The mild reaction conditions and high chloride utilization efficiency promise a bright future for chlorination reactions. The Royal Society of Chemistry 2014.
- Wang, Ying,Li, Lina,Ji, Hongwei,Ma, Wanhong,Chen, Chuncheng,Zhao, Jincai
-
supporting information
p. 2344 - 2346
(2014/03/21)
-
- Activation of rhenium(I) toward substitution in fac -[Re(N,O′ -Bid)(CO)3(HOCH3)] by Schiff-base bidentate ligands (N,O′ -Bid)
-
A series of fac-[Re(N,O′-Bid)(CO)3(L)] (N,O′-Bid = monoanionic bidentate Schiff-base ligands with N,O donor atoms; L = neutral monodentate ligand) has been synthesized, and the methanol substitution reactions have been investigated. The complexes were characterized by NMR, IR, and UV-vis spectroscopy. X-ray crystal structures of the compounds fac-[Re(Sal-mTol)(CO)3(HOCH3)], fac-[Re(Sal-pTol)(CO) 3(HOCH3)], fac-[Re(Sal-Ph)(CO)3(HOCH 3)], and fac-[Re(Sal-Ph)(CO)3(Py)] (Sal-mTol = 2-(m-tolyliminomethyl)phenolato; Sal-pTol = 2-(p-tolyliminomethyl)phenolato; Sal-Ph = 2-(phenyliminomethyl)phenolato; Py = pyridine) are reported. Significant activation for the methanol substitution is induced by the use of the N,O bidentate ligand as manifested by the second order rate constants, with limiting kinetics being observed for the first time. Rate constants (25 C) (k1 or k3) and activation parameters (ΔH ka, kJ mol-1; ΔS ka, J K-1 mol-1) from Eyring plots for entering nucleophiles as indicated are as follows: fac-[Re(Sal-mTol)(CO)3(HOCH3)] 3-chloropyridine: (k 1) 2.33 ± 0.01 M-1 s-1; 85.1 ± 0.6, 48 ± 2; fac-[Re(Sal-mTol)(CO)3(HOCH3)] pyridine: (k1) 1.29 ± 0.02 M-1 s-1; 92 ± 2, 66 ± 7; fac-[Re(Sal-mTol)(CO)3(HOCH3)] 4-picoline: (k1) 1.27 ± 0.05 M-1 s-1; 88 ± 2, 53 ± 6; (k3) 3.9 ± 0.03 s-1; 78 ± 8, 30 ± 27; (kf) 1.7 ± 0.02 M-1 s-1; 86 ± 2, 49 ± 6; fac-[Re(Sal-mTol)(CO) 3(HOCH3)] DMAP (k3) 1.15 ± 0.02 s -1; 88 ± 2, 52 ± 7. An interchange dissociative mechanism is proposed.
- Brink, Alice,Visser, Hendrik G.,Roodt, Andreas
-
supporting information
p. 8950 - 8961
(2013/09/02)
-
- METHOD FOR THE PREPARATION OF CHLORINATED PYRIDINES
-
The invention discloses a method for the preparation of halogenated pyridines by decarbonylation of pyridine acyl halides.
- -
-
Page/Page column 20
(2013/03/26)
-
- Copper-catalyzed conversion of aryl and heteroaryl bromides into the corresponding chlorides
-
An efficient method for the synthesis of aryl and heteroaryl chlorides is described. The reactions of aryl and heteroaryl bromides with tetramethylammonium chloride proceeded smoothly in the presence of a copper catalyst under mild reaction conditions to produce the corresponding chlorides in satisfactory to excellent yields.
- Feng, Xiujuan,Qu, Yiping,Han, Yanlei,Yu, Xiaoqiang,Bao, Ming,Yamamoto, Yoshinori
-
supporting information
p. 9468 - 9470
(2012/10/29)
-
- Palladium-N-heterocyclic carbene an efficient catalytic system for the carbonylative cross-coupling of pyridine halides with boronic acids
-
Carbonylative cross-coupling of different pyridyl halides with various boronic acids was studied using catalytic systems constituted of N-heterocyclic carbene type ligands and palladium. These systems easily obtained in situ from the corresponding imidazolium salt and palladium acetate appear more efficient toward bromopyridines than catalysts based on hindered and basic alkylphosphines such as tricyclohexylphosphine. Their higher efficiency was also evidenced by coupling using chloro- or dichloropyridines and chloroquinolines, which practically do not react with catalytic systems based on phosphines.
- Maerten, Eddy,Sauthier, Mathieu,Mortreux, André,Castanet, Yves
-
p. 682 - 689
(2007/10/03)
-
- A general method for the deoxygenation of aromatic N-oxides using RuCl 3?xH2O
-
An efficient, simple and selective method for the deoxygenation of aromatic N-oxides, such as N-arylnitrones, azoxybenzenes, N-heteroarene N-oxides using ruthenium(III) chloride to afford deoxygenated products in excellent yields, is described.
- Kumar, Sanjay,Saini, Anil,Sandhu, Jagir S.
-
p. 8737 - 8739
(2007/10/03)
-
- Hiyama cross-coupling of chloro-, fluoro-, and methoxypyridyltrimethylsilanes: Room-temperature novel access to functional bi(het)aryl
-
(Chemical Equation Presented) The incorporation of chloro, fluoro, or methoxy substituents on the pyridine ring of pyridyltrimethylsilanes allowed us to perform efficient Hiyama cross-coupling with various (het)aryl halides. The reactions proceeded smoothly at room temperature leading to the corresponding functional bis(het)aryl in fair to excellent yields. The presence of pyridine nitrogen α to the trimethylsilyl group was requisite to achieve the cross-coupling.
- Pierrat, Philippe,Gros, Philippe,Fort, Yves
-
p. 697 - 700
(2007/10/03)
-
- An indium mediated efficient chemoselective deoxygenation of N-oxides and nitrones
-
A simple and inexpensive procedure for the deoxygenation of N-oxides, such as N-arylnitrones, azoxybenzenes and N-heteroarene N-oxides with indium trichloride in acetonitrile at ambient pressure is described. The procedure gives high yields of deoxygenated products.
- Ilias, Md,Barman, Dhiren C,Prajapati, Dipak,Sandhu, Jagir S
-
p. 1877 - 1879
(2007/10/03)
-
- Process for preparation of 2-chloropyridine
-
Described are processes for producing 2-chloropyridine by reacting pyridine with molecular chlorine in the vapor phase in the presence of a catalyst which includes an organic compound which generates free radicals under the conditions of the reaction.
- -
-
Page column 4-5
(2010/01/31)
-
- Selective palladium-catalysed carbonylations of dichloroquinoline and simple dichloropyridines
-
Dichloroquinoline and some dichloropyridines undergo selective alkoxycarbonylation in the presence of carbon monoxide, an alcohol and PdCl2(PPh3)2 as a catalyst, affording chloro-monoester and/or diesters in good yields under selected reaction conditions.
- Najiba, Douja,Carpentier, Jean-Francois,Castanet, Yves,Biot, Christophe,Brocard, Jacques,Mortreux, Andre
-
p. 3719 - 3722
(2007/10/03)
-
- New aspect of methanesulfonyl chloride: Unusual deoxygenations of pyridine N-oxides with methanesulfonyl chloride and triethylamine
-
Treatment of several pyridine N-oxides with an excess of methanesulfonyl chloride and triethylamine brought about a deoxygenation reaction to give efficiently the corresponding reduction products without chlorination of the pyridine nucleus.
- Morimoto, Yoshiki,Kurihara, Hajime,Yokoe, Chiho,Kinoshita, Takamasa
-
p. 829 - 830
(2007/10/03)
-
- Effective charge on the nucleophile and leaving group during the stepwise transfer of the triazinyl group between pyridines in aqueous solution
-
Second-order rate constants (kxpy) have been measured for the displacement reaction between substituted pyridines (xpy) and 1′-(2,6-diphenoxy-1,3,5-triazin-2-yl)pyridinium ion in aqueous solution. The rate constants for the reverse reaction (k-xpy) have also been measured for substituted pyridine leaving groups. The plots of log kxpy and log k-xpy against pKaxpy each consist of two intersecting linear correlations consistent with a two-step mechanism involving a Meisenheimer-like intermediate. The overall transfer of the triazin-2-yl group between substituted pyridines has a βeq value of 1.25. There is negligible coupling between the bonding changes in both steps, and the substituent effects indicate that bond formation is half complete in the addition step. Reaction of substituted pyridines with 2,6-diphenoxy-1,3,5-triazin-2-yl chloride has a similar bonding change in the addition step. The 1′-triazin-2-ylpyridinium ion species exist in aqueous solution in equilibrium with the pseudobase formed by addition of water at the 2-position of the pyridinium ring.
- Cullum, Neil R.,Renfrew, A. Hunter M.,Rettura, Donatella,Taylor, John A.,Whitmore, James M. J.,Williams, Andrew
-
p. 9200 - 9205
(2007/10/03)
-
- ORGANIC SYNTHESIS USING ORGANOSULFUR-NITRITES AND -NITRATES
-
Thionitrites or thionitrates have been considered to be unstable.However, bulky groups' thio-NOn such as t-butylthio-nitrites and -nitrates have been readily synthesized and found to be stable enough for the use of the useful organic syntheses as an excellent nitrosation and diazotization reagents under mild conditions.Direct conversion of amines to the corresponding halides in the presence of copper halides (II), fluorination of heterocyclic amines in the presence of sodium tetrafluoroborate, α- oximation of methylene groups in ketones, facile cleavage of C=N bond to ketones, and desulfurization of thioacetals and thioketals, and other useful organic syntheses are described.
- Kim, Yong Hae
-
p. 249 - 260
(2007/10/02)
-
- On the High-Yielding Chlorodediazonation not requiring Catalysis by Copper Salts
-
Reaction of benzenediazonium tetrafluoroborate, p-methoxybenzenediazonium tetrafluoroborate, p-ethoxycarbonylbenzenediazonium tetrafluoroborate and 3-pyridinediazonium tetrafluoroborate in a 3:1 mixture of tetrachloromethane and acetonitrile with ferrous and ferric chloride yields the corresponding aryl chlorides in nearly quantitative yield.The reaction mechanism seems to be similar to that of the classical Sandmeyer reaction involving an initial electron transfer from the reductant to the arenediazonium ion.On the other hand, treatment of 2-aminopyridine or 2-amino-4-methylpyridine with dinitrogen trioxide in dry dichloromethane in the presence of hydrogen chloride and tetrabutylammonium chloride but in the absence of redicing agents afforded 2-chloropyridine or 2-chloro-4-methylpyridine, respectively, in 95 percent yield in a reaction which either has a cation as intermediate or follows an SNAr mechanism.The reactivity of the diazonium ion seems to determine whether the chlorodediazoniation goes through an aryl radical or follows another route, possibly via the SNAr mechanism or the cation; most arenediazonium ions seem to react through the aryl radical, while 2-pyridinediazonium and most alkyldiazonium ions react via other routes.
- Daasbjerg, Kim,Lund, Henning
-
p. 157 - 162
(2007/10/02)
-
- Kinetics and mechanism of the formation of N-vinyl pyridinium cations in elimination reactions in aqueous base
-
The rates of the elimination reactions of N-(2-bromoethyl) pyridinium cations (1) and N,N'-ethylene bispyridinium dications (3) to give the corresponding N-vinyl pyridinium cations (2) have been measured spectrophotometrically in basic aqueous solutions (ionic strength 0.1, 25 deg C) for a variety of substituents in the pyridine rings of each of these classes of pyridinium cation.The reaction kinetics are first order in 1 or 3 and first order in hydroxide ion.Bronsted-type plots of the second-order rate constants (kOH) as a function of the basicity (as pKBH) of the corresponding substituted pyridine are nonlinear for each of 1 and 3 and can be interpreted in terms of E1cb reaction mechanism.For 1, the Bronsted-type plot displays two distinct ''concave down'' linear regions; rate-determining deprotonation for pKBH > 5.16 (slope = -0.30), and a change in rate-determining step to bromide ion departure for pKBH > 5.16 (slope -0.58).For 3, the Bronsted-type plot appears to be smoothly curved for symmetrically disubstituted bispyridinium dications, as a consequence of the multiple substituent effects upon each step of the E1cb reactions of these dications.However, log kOH for 3 is a smooth linear function of the previously reported log kOH for the E1cb reactions of N-(2-cyanoethyl) pyridinium cations over a range in which a change in rate-determining step has been directly demonstrated for these latter cations.Thus a change in rate-determining step as a function of pyridine basicity is also required within the E1cb mechanism for 3.The E1cb reactions of 1 are approximately 104-fold faster than the corresponding hydroxide ion catalyzed E2 eliminations from 2-phenylethyl bromides that are isoelectronic with 1.
- Bunting, John W.,Toth, Andrea,Kanter, James P.
-
p. 1195 - 1203
(2007/10/02)
-
- A Change in the Rate-Determining Step in the E1cB Reactions of N-(2-(4-Nitrophenyl)ethyl)pyridinium Cations
-
Second-order rate constants have been measured (aqueous solution, I = 1.0, 25 deg C) for the hydroxide ion catalyzed elimination reactions of 12 N-(2-(4-nitrophenyl)ethyl)pyridinium cations (3) bearing a variety of substituents in the pyridine ring.Broensted plots as a function of the basicity of the pyridine leaving group are concave-down, which is consistent with a change in rate-determining step within an E1cB mechanism.These plots are characterized by βlg = -0.17 for the rate-determining deprotonation for pKBH lg = -0.39 for the rate-determining expulsion of the pyridine nucleofuge from the carbanionic intermediate for pKBH > 6.5.Elimination reactions in basic D2O occur without any significant incorporation of deuterium into the 4-nitrostyrene product, and require the presence of a hydrogen-bonded carbanionic intermediate in which nucleofuge expulsion occurs faster than exchange of hydrogen-bonding water molecules.Rate-determining deprotonation in these elimination reactions occurs 50-fold more slowly than for the corresponding reactions of the N-quinuclidinium cations that have also been reported to have βlg = -0.17, but which do not show an analogous change in the rate-determining step upon variation of the nucleofuge basicity.The analogous elimination of the 1-methyl-3-imidazolium cation occurs a further 30-fold more slowly than that predicted for 3 having a pyridine leaving group of the same basicity as 1-methylimidazole.The E1cB reactions of 3 are similar to the analogous reactions of N-(2-cyanoethyl)pyridinium cations (1) in displaying a change in the rate-determining step with nucleofuge basicity; however, theβlg values for 1 and 3 are quite different for both k1 and k2/k-1.
- Bunting, John W.,Kanter, James P.
-
p. 6950 - 6954
(2007/10/02)
-
- An Efficient General Method for the Deoxygenation of N-Arylnitrones, Azoxybenzenes, and N-Heteroarene N-Oxides
-
A new general method for the deoxygenation of N-oxides such as N-arylnitrones, azoxybenzenes, and N-heteroarene N-oxides uses aluminum iodide in acetonitrile.The deoxygenated products are obtained in high yields.
- Konwar, Dilip,Boruah, Romesh C.,Sandhu, Jagir S.
-
p. 337 - 339
(2007/10/02)
-
- Equilibration of N-(2-cyanoethyl)pyridinium cations with substituted pyridines and acrylonitrile. A change in rate-determining step in an E1cb reaction
-
The rates of equilibration of N-(2-cyanoethyl)pyridinium cations (1) with the corresponding pyridines and acrylonitrile have been measured in aqueous solutions of ionic strength 0.1 at 25 °C. Second-order rate constants (kOH) have been obtained for the hydroxide ion catalyzed elimination reactions of 16 ring-substituted 1 having pyridine leaving groups of pKBH in the range 1.5-9.7. Bronsted plots of log kOH vs pKBH are "concave down" with two distinct linear regions having β1g = -0.30 (for pKBH 1g = -0.93 (for pKBH > 5.8). This observation is consistent with a change in rate-determining step within an E1cb reaction mechanism from rate-determining deprotonation of 1 (i.e., (E1cb)irrev) for pKBH rev) for pKBH > 5.8. This interpretation is supported by 1H NMR spectral observations in basic D2O, which show no incorporation of deuterium into the acrylonitrile product for pKBH BH > 5.8. Rates of nucleophilic attack of pyridines and pyridinone anions (pKBH > 6) upon acrylonitrile have also been measured. These display a linear Br?nsted plot of βnuc = 0.20. Combination of β1g and βnuc gives βeq = 0.13 for the Michael-type addition of pyridinium cations to acrylonitrile to produce 1. Although the rates of the addition of pyridines of pKBH nuc = 0.20 for pyridines of pKBH > 5.8 to rate-determining protonation of the carbanionic intermediate with βnuc = 0.83 for pyridine nucleophiles of pKBH irrev region but is extremely weak under the current experimental conditions.
- Bunting, John W.,Toth, Andrea,Heo, Christina K. M.,Moors, Rodney G.
-
p. 8878 - 8885
(2007/10/02)
-
- POTENTIOMETRIC STUDIES ON THE REACTION OF PICRIC ACID WITH SOME AROMATIC AMINES IN METHYL ISOBUTYL KETONE
-
The reaction between picric acid and some aniline and pyridine derivatives has been investigated in methyl isobutyl ketone by the potentiometric method.Overall picrate formation constants KBHA, ammonium cationic acid dissociation constants KBH+ and apparent ion-pair formation Ki* and dissociation Kd* constants have been determined.
- Smagowski, Henryk,Bartnicka, Halina
-
p. 201 - 209
(2007/10/02)
-
- THE PYRIDYL CATION AS A REACTIVE INTERMEDIATE IN THE PHOTOREACTION OF IODOPYRIDINES WITH BENZENES
-
The electrophilic behavior of the reactive entity in the photosubstitution of benzenes with 2-iodopyridine was found to be ascribable to the intermediary 2-pyridyl cation, rather than the electrophilic 2-pyridyl radical.
- Ohkura, Kazue,Seki, Koh-ichi,Terashima, Masanao,Kanaoka, Yuichi
-
p. 3433 - 3436
(2007/10/02)
-
- PHOTODECARBOXYLATIVE CHLORINATION OF CARBOXYLIC ACIDS VIA THEIR BENZOPHENONE OXIME ESTERS
-
Decarboxylative chlorination of various aromatic and aliphatic carboxylic acids is performed successfully by the photolysis of their benzophenone oxime esters in carbon tetrachloride and corresponding chloro compounds are prepared in good yields.High selective generation of the certain radical and efficiency of the stable radical precursor, benzophenone oxime ester, afford much advantage for radical chemistry.
- Hasebe, Masato,Tsuchiya, Takashi
-
p. 6287 - 6290
(2007/10/02)
-
- Mild Selective Deoxygenation of Amine Oxides by Tin-Tin Bonded Derivatives
-
A new method of deoxygenation of amine oxides with tin reagent is proposed.It utilizes the reductive properties of the tin-tin bond in hexabutyldistannane or 1,2-dichlorotetrabutyldistannane.Oxides of tertiary amines are reduced into amines by hexabutyldistannane in high yields, whereas pyridine N-oxides react cleanly with 1,2-dichlorotetrabutyldistannane to give the corresponding pyridines.These reactions occur under mild conditions and are very selective.
- Jousseaume, Bernard,Chanson, Evelyne
-
-
- HOMOTRANSMETALLATION DES HALOGENO-3 PYRIDINES BROMEES EN -2 OU -4 PAR LE N-BUTYLLITHIUM. PROPOSITION D'UN NOUVEAU MECANISME DE TELESUBSTITUTION DU BROME.
-
These are new examples of the homotransmetallation reaction.Instead of the ordinary bromo-metal exchange it is possible to obtain selectively from the 2-bromo 3-fluoro or 2-bromo 3-chloro pyridines the 2-bromo 3-halogeno 4-lithio pyridines, which is very interesting for synthetic utility.From the 4-bromo 3-halogeno pyridines, we can see an isomerization with an halogen dance mechanism and we obtain the 5-bromo 3-halogeno 4-lithio pyridines.In the case of the 2-bromo 3-fluoro pyridine we explain a telesubstitution of bromine from 2 to 4 by a transitory homotransmetallation reaction during the Li-Br exchange.
- Mallet, M.,Queguiner, G.
-
p. 2253 - 2262
(2007/10/02)
-
- PYRIDINIUM ION REACTIVITIES: SUBSTITUENT EFFECT ON THE REVERSE MENSCHUTKIN REACTION OF 1-METHYLPYRIDINIUM CATIONS WITH IODIDE ANION
-
Substituent effect on the reverse Menschutkin reaction of 1-methylpyridinium cations with iodide anion can be described in terms of the LArSR equation with =3.60 which provides evidence against very late transition state of the nitrogen-to-iodine transmethylation.
- Sawada, Masami,Takai, Yoshio,Chong, Chang,Hanafusa, Terukiyo,Misumi, Soichi
-
p. 5065 - 5068
(2007/10/02)
-
- Mercaptoimidazole derivatives
-
Novel substituted 2-mercaptoimidazoles of the formula STR1 in which at least one of the radicals R1 and R2 is a substituted or unsubstituted heteroaryl group and the other is a substituted or unsubstituted aryl group, R3 is hydrogen or lower alkyl, n is 0, 1 or 2 and R4 is a substituted or unsubstituted aliphatic hydrocarbon radical and their pharmaceutically usable salts exhibit anti-inflammatory, anti-nociceptive and/or antithrombotic activity.
- -
-
-