- Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
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The iron-catalyzed hydrogen transfer strategy has been applied to the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles and benzimidazoles.
- Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
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p. 15396 - 15405
(2020/12/02)
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- Rational design of fluorescent probes for targeted: In vivo nitroreductase visualization
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Nitroreductase (NTR) has been recognized as a biomarker for identifying the hypoxic status of cancers. Therefore, it is of high scientific interest to design effective fluorescent probes for tracking NTR activity. However, studies on elucidation of the structure-performance relationship of fluorescent probes and those providing valuable insight into optimized probe design have rarely been reported. Three BODIPY based fluorescent probes were made by conjugation of para-, ortho-, and meta-nitrobenzene to the BODIPY core via a thiolether bond, respectively. Our study revealed that the linkage and nitro substituent position significantly influence the capability of nitroreductase detection.
- Chen, Ji-An,Gao, Jie,Gu, Xianfeng,Li, Mimi,Tan, Jiahui,Yin, Xiaofan,Zhao, Zhen
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supporting information
p. 4744 - 4747
(2020/07/13)
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- Mitsunobu C-alkylation of β-alkoxycarbonyl 2-nitrobenzenesulfones and its use for the rapid synthesis of novel benzothiazine derivatives
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Herein, we report the first examples of the Mitsunobu alkylation of β-alkoxycarbonyl 2-nitrobenzenesulfones. Wang resin was acylated with α-halocarboxylic acids followed by the reaction with 2-nitrothiophenols. After oxidation with m-chloroperbenzoic acid, the immobilized β-alkoxycarbonyl 2-nitrobenzensulfones were subjected to alkylation with various alcohols. The reaction outcome strongly depended on the selection of the alkylating species. After the reduction of the nitro group, acid-mediated cleavage and subsequent cyclization, the C2-(di)substituted benzothiazin-3(4H)-one 1,1-dioxides were obtained in high crude purities and good overall yields.
- Drábiková, Martina,Kraj?ovi?ová, Soňa,Soural, Miroslav
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p. 6296 - 6306
(2017/10/06)
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- Dynamic kinetic resolution of allylic sulfoxides by Rh-catalyzed hydrogenation: A combined theoretical and experimental mechanistic study
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A dynamic kinetic resolution (DKR) of allylic sulfoxides has been demonstrated by combining the Mislow [2,3]-sigmatropic rearrangement with catalytic asymmetric hydrogenation. The efficiency of our DKR was optimized by using low pressures of hydrogen gas to decrease the rate of hydrogenation relative to the rate of sigmatropic rearrangement. Kinetic studies reveal that the rhodium complex acts as a dual-role catalyst and accelerates the substrate racemization while catalyzing olefin hydrogenation. Scrambling experiments and theoretical modeling support a novel mode of sulfoxide racemization which occurs via a rhodium π-allyl intermediate in polar solvents. In nonpolar solvents, however, the substrate racemization is primarily uncatalyzed. Computational studies suggest that the sulfoxide binds to rhodium via O-coordination throughout the catalytic cycle for hydrogenation.
- Dornan, Peter K.,Kou, Kevin G. M.,Houk,Dong, Vy M.
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supporting information
p. 291 - 298
(2014/01/23)
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- O-Nitrophenyl sulfoxides: Efficient precursors for the mild preparation of alkenes
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(Chemical Equation Presented) o-Nitrophenyl sulfoxides were found to be efficient synthetic precursors of various alkene types. The elimination occurs in toluene and NaOAc to generate substituted and terminal alkenes. Alkene products were easily obtained in high purity due to the simultaneous precipitation of the o-nitrophenyl sulfenic acid byproduct. The methods described have practical applications for the preparation of unsaturated compounds under mild, thermolytic conditions. 2009 American Chemical Society.
- Lu, Xiao,Long, Timothy E.
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supporting information; experimental part
p. 249 - 252
(2010/04/06)
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- PREPARATION OF ALKENES BY MILD THERMOLYSIS OF SULFOXIDES
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Embodiments of this disclosure, among others, encompass methods for generating alkenes under mild thermolytic conditions that can provide almost total conversion of a precursor compound to an alkene without isomerization or the need to chromatographically purify the final product By selectively blocking the amino and carboxy groups of the depvatized amino acid, the methods of the disclosure provide for the synthesis of a peptide having the vinylglycine moiety at either the carboxy or the amino terminus of the peptide The mild conditions for the thermolytic removal of an o-NO2-phenyl substituted aryl group ensure that there is minimal if any damage to thermally sensitive conjugates such as a peptide bearing the vinylglycine The methods of the present disclosure have practical applications for the preparation of unsaturated compounds under mild, thermolytic conditions.
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Page/Page column 29-30
(2010/07/02)
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- Preparation of vinylglycines by thermolysis of homocysteine sulfoxides
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The synthesis and efficacy of preparing Cbz-VG-OMe (1) by thermolysis of alkyl and aryl homocysteine sulfoxides were surveyed. This investigation determined that aryl sulfoxide analogs were more effective for the reaction and that the 2-nitrophenyl analog 10f possessed a unique ability to syn eliminate at temperatures as low as 100 °C. The thermolysis of sulfoxide 10f was additionally discovered to occur under toluene reflux and when sodium acetate was added, Cbz-VG-OMe (1) could be obtained in high purity by simple filtration of the precipitated sulfenic acid byproduct 12. This mild protocol which was also applied in the synthesis of VG dipeptide 13 would have utility in the general synthesis of olefins and alkenes from 2-nitrophenylsulfoxides.
- Patel, Sravan Kumar,Long, Timothy E.
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supporting information; experimental part
p. 5067 - 5070
(2009/12/01)
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- Unsymmetric aryl-alkyl disulfide growth inhibitors of methicillin-resistant Staphylococcus aureus and Bacillus anthracis
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This study describes the antibacterial properties of synthetically produced mixed aryl-alkyl disulfide compounds as a means to control the growth of Staphylococcus aureus and Bacillus anthracis. Some of these compounds exerted strong in vitro bioactivity. Our results indicate that among the 12 different aryl substituents examined, nitrophenyl derivatives provide the strongest antibiotic activities. This may be the result of electronic activation of the arylthio moiety as a leaving group for nucleophilic attack on the disulfide bond. Small alkyl residues on the other sulfur provide the best activity as well, which for different bacteria appears to be somewhat dependent on the nature of the alkyl moiety. The mechanism of action of these lipophilic disulfides is likely similar to that of previously reported N-thiolated β-lactams, which have been shown to produce alkyl-CoA disulfides through a thiol-disulfide exchange within the cytoplasm, ultimately inhibiting type II fatty acid synthesis. However, the mixed alkyl-CoA disulfides themselves show no antibacterial activity, presumably due to the inability of the highly polar compounds to cross the bacterial cell membrane. These structurally simple disulfides have been found to inhibit β-ketoacyl-acyl carrier protein synthase III, or FabH, a key enzyme in type II fatty acid biosynthesis, and thus may serve as new leads to the development of effective antibacterials for MRSA and anthrax infections.
- Turos, Edward,Revell, Kevin D.,Ramaraju, Praveen,Gergeres, Danielle A.,Greenhalgh, Kerriann,Young, Ashley,Sathyanarayan, Nalini,Dickey, Sonja,Lim, Daniel,Alhamadsheh, Mamoun M.,Reynolds, Kevin
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p. 6501 - 6508
(2008/12/21)
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- A comparison of commercial microwave reactors for scale-up within process chemistry
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Seven commercially available microwave reactors designed for limited scale-up have been investigated using a highly reliable and robust reaction (the Newman-Kwart rearrangement). The use of a single reaction has enabled the comparison to be made across the range of different reactor types and scales. Overall, all reactors gave reliable scale-up from small scale, and performance equivalent to one another on large scale. A more detailed comparison between them is given in the concluding section.
- Moseley, Jonathan D.,Lenden, Philip,Lockwood, Mark,Ruda, Katinka,Sherlock, Jon-Paul,Thomson, Anthony D.,Gilday, John P.
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- N-alkylthio beta-lactams, alkyl-coenzyme a asymmetric disulfides, and aryl-alkyl disulfides as anti-bacterial agents
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The present invention provides N-alkylthio β-lactams and disulfide compounds (e.g., alkyl-coenzyme A asymmetric disulfides or aryl-alkyl disulfides), compositions containing such compounds, and method of their use as anti-bacterial agents.
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Page/Page column 9
(2008/12/07)
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- A rapid and efficient cleavage of organic disulfides to mercaptans using ZrCl4/NaBH4
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A practical and cheaper reagent system ZrCl/NaBH4 is used for the reductive cleavage of organic disulfides to mercaptans under mild conditions, in excellent yields.
- Purushothama Chayr,Rajaram,Iyengar
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p. 3905 - 3911
(2007/10/03)
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- Oxidative cleavage of S-Arylmercaptoacetic acids by pyridinium chlorochromate: Kinetic and correlation analysis
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Kinetics of oxidation of 24 S-Arylmercaptoacetic acids (SAMA) by pyridinium chlorochromate (PCC) have been studied in acid medium. The product of oxidation is the corresponding thiophenol. The rate data of meta- and para-substituted acids have been correlated well with σI, σ°R values and the meta-compounds correlate well with F,R values. The reaction constants are negative and of smaller magnitudes. Further, the ortho-substituted acids show a good correlation with triparametric equation involving Taft's σI and σ°R and charton's steric parameter v. There is no considerable steric contribution to the total orthosubstituent effect. Based on these observations, the mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
- Kabilan,Girija,Rajagopal
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p. 683 - 688
(2007/10/03)
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- Structure-based design and synthesis of substituted 2-butanols as nonpeptidic inhibitors of HIV protease: Secondary amide series
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The design, synthesis, and crystallographic analysis of protein- inhibitor complexes is described for a novel series of nonpeptidic HIV protease (HIV Pr) inhibitors. Beginning with a cocrystal structure of a Phe- Pro peptidomimetic bound to the HIV Pr, design was initiated that resulted in the substituted 2-butanol compound 8 as the lead compound (K(i) = 24.5 μM, racemic mixture). Modifications on the initial compound were then made on the basis of its cocrystal structure with HIV Pr and inhibition data, resulting in compounds with enhanced potency against the enzyme (compound 18, K(i) = 0.48 μM). These inhibitors were found to bind to the enzyme essentially as predicted on the basis of the original design hypothesis. Stereospecific synthesis of individual enantiomers confirmed the prediction of a binding preference for the S alcohol stereochemistry. Modest antiviral activity was demonstrated for several of the more potent HIV Pr inhibitors in a HIV-1 infected CEM-SS cell line.
- Reich, Siegfried H.,Melnick, Michael,Pino, Mark J.,Fuhry, Mary Ann M.,Trippe, Anthony J.,Appelt, Krzysztof,Davies II, Jay F.,Wu, Bor-Wen,Musick, Linda
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p. 2781 - 2794
(2007/10/03)
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- Oxidative Cleavage of S-Arylmercaptoacetic Acids by Sodium Perborate: Kinetic and Correlation Study
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Kinetics of oxidation of twenty six S-arylmercaptoacetic acids (SAMA) (I) by sodium perborate (PB) have been studied in acid medium.The product of oxidation is the corresponding thiophenol.The rate data of meta- and para-substituted acids have been correlated with DSP equations.While the para-compounds correlate well with ?I and ?0R values, the meta-compounds correlate well with ?I and ?-R values.The reaction constants are negative and of smaller magnitudes.Further, the ortho-substituted acids show a good correlation with a triparametric equation involving Taft's ?I and ?0R and Charton's steric parameter ν.There is a considerable steric contribution to the total ortho-substituent effect.Based on these observations, mechanism involving the formation of protonated arylsulfinylacetic acid intermediate, followed by an intramolecular rearrangement leading to the product thiophenol has been proposed.
- Kabilan, S.,Pandiarajan, K.,Krishnasamy, K.,Sankar, P.
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p. 443 - 452
(2007/10/02)
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- Synthesis, characterization, and Ca2+ antagonistic activity of diltiazem metabolites.
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Diltiazem is a calcium antagonist widely used in the treatment of angina and hypertension. The contributions of metabolites of diltiazem to the vasorelaxant effects of diltiazem were investigated. The synthesis and spectroscopic characterization of eight major cis-diltiazem metabolites are described. Three of the compounds--N, O-didemethylated metabolite (21), O-demethylated metabolite (22), and diltiazem N-oxide (27)--have been recently reported and have not previously been synthesized. The identities of all eight synthetic metabolites have been verified with samples obtained from human urine using combined LC-MS/MS. The Ca2+ antagonistic activities of diltiazem and its metabolites (except 27) were studied on hamster aorta preparations depolarized with KCl. The order of potencies (IC50 +/- SE, microM) is as follows: diltiazem (0.98 +/- 0.47) greater than 17 (2.46 +/- 0.38) greater than or equal to 23 (3.27 +/- 1.02) greater than 26 (20.2 +/- 10.5) greater than 22 (40.4 +/- 15.4) greater than or equal to 25 (45.5 +/- 18.1) greater than 21 (112.2 +/- 33.2) greater than or equal to 24 (126.7 +/- 24.2). Structure-activity relationships are also discussed.
- Li,Farmer,Xie,Quilliam,Pleasance,Howlett,Yeung
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p. 3246 - 3253
(2007/10/02)
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- β-D-phenylthioxylosides, their method of preparation and their use as therapeutic agents
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The present invention relates, by way of novel industrial products, to the β-D-phenylthioxyloside compounds of the formula STR1 in which: X represents a sulfur atom or an oxygen atom; R1, R2 and R3, which are identical or different, each represent a hydrogen atom, a nitro group, a cyano group, a group --CO--R (in which R represents a C1 -C4 alkyl group or a trifluoromethyl group), an amino group, an acetamido group (NHCOCH3), a C1 -C4 alkoxy group, a trifluoromethyl group or a phenyl group substituted by one or more cyano, nitro or trifluoromethyl groups, it being possible for R1 and R2, taken together, to form, with the phenyl group to which they are bonded, a β-naphthalenyl group which is unsubstituted or substituted by one or more cyano, nitro or trifluoromethyl groups; and Y represents the hydrogen atom or an aliphatic acyl group. These compounds are useful as therapeutic agents, especially as venous antithrombotics.
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- Conversion of o-Nitrothiophenols into o-Aminobenzenesulphonic Acids
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The mechanism of conversion of o-nitrothiophenols into o-aminobenzenesulphonic acids in aqueous dioxane has been investigated with particular reference to evidence for the rate-determining formation of a cyclic intermediate.This intermediate is susceptible to interception by both external and internal nucleophilic functions, and the sulphonic acid is shown by isotope labelling experiments to take two oxygen atoms from H2(18)O in the reaction mixture, under conditons in which neither starting materials nor products exchange with H2(18)O.A tentative pathway is advanced.
- Bamfield, Peter,Greenwood, David,Lotey, Harvinder,Stirling, Charles J. M.
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p. 691 - 696
(2007/10/02)
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- Quinones. Part 11. The Reaction of o-Aminothiophenol with o-Benzo- and o-Naphtho-quinones: A New Route to 1H-Phenothiazin-1-ones
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1H-Phenothiazin-1-ones can be obtained by the condensation of o-aminothiophenol with 3,5-di-t-butyl- and 3-t-butyl-5-phenyl-o-benzoquinones.In the absence of large blocking groups the phenothiazinones are unstable.A methyl group at C-4 leads via the quinone-methide tautomer, to formation of a spiro-dimer the crystal structure of which was determined by X-ray analysis.By further reaction with o-aminothiophenol, 1H-phenothiazin-1-ones yield triphenodithiazines (benzothiazinophenothiazines). o-Naphthoquinones do not form benzo-1H-phenothiazin-1-ones with o-aminothiophenol.The parent compound yields 4-hydroxy-3H-benzophenothiazin-3-one by initial thiol addition at C-4 followed by rearrangement.
- Mackenzie, Neil E.,Surendrakumar, Sivagnanasundram,Thomson, Ronald H.,Cowe, Heather J.,Cox, Philip J.
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p. 2233 - 2242
(2007/10/02)
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- Process for preparing threo-2-hydroxy-3-(4-methoxyphenyl)-3-(2-nitrophenylthio)-propionic ester
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A threo-2-hydroxy-3-(4-methoxyphenyl)-3-(2-nitrophenylthio)propionic ester of the formula: STR1 wherein R is an ester residue, is prepared by condensing a trans-3-(4-methoxyphenyl)glycidic ester of the formula: STR2 wherein R is the same as defined above, with 2-nitrothiophenol in the presence of a Lewis acid.
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- SYNTHESIS AND CONFIGURATIONAL STUDIES OF ARYL CYCLOPROPYL SULFONES
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The cycloaddition of arylthiocarbenes to styrene gave stereospecifically cis-1-(arylthio)-2-phenylcyclopropanes, which were subsequently oxidized to the corresponding sulfones.The cyclopropanation of α,β-unsaturated sulfones with dimethylsulfonium methylide yielded stereoselectively trans-1-(arylsulfonyl)-2-arylcyclopropanes.The configurational assignments of these compounds have been arrived at on the basis of IR and PMR spectral data.Chemical shifts for ring protons and other substituents reveal that all the substituents tend to cause protons cis to them to appear at higher fields than those trans to them.This has been used as a criterion to distinguish between cis and trans aryl cyclopropyl sulfones.
- Reddy, D. Bhaskar,Balaji, T.,Reddy, B. Venkataramana
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p. 297 - 306
(2007/10/02)
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- 149. Notizen zur Synthese von 2-Aminophenylsulfonen
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Syntheses of the alkyl, cycloalkyl and aryl 2-aminophenyl sulfones 10 were achieved by oxidation of the corresponding 2-nitrophenyl sulfides 7 to the 2-nitrophenyl sulfones 9 followed by ethanolic Bechamp-reduction.The sulfides 7 in turn were obtained by either reactions of 2-nitro-thiophenol (8) with the appropriate alkyl and cycloalkyl halides or of 2-chloro-nitrobenzene (5) with the relevant thiols.Condensation of 2-nitrobenzenesulfinic acid (3) with bromoacetic acid in aqueous alkaline solution led - presumably via 2-nitrophenylsulfonylacetic acid (4) - to methyl2-nitrophenyl sulfone (1), reduction of which gave 2-aminophenyl methyl sulfone (2).Treatment of 2-aminothiophenol (11) with t-butyl alcohol in aqueous sulfuric acid gave 2-aminophenyl t-butyl sulfide (12), which was acetylated to o-t-butylthio-acetanilide (13).Oxidation of the latter to o-t-butylsulfonyl-acetanilide (14) followed by hydrolysis led to 2-aminophenyl t-butyl sulfone (15).
- Courtin, Alfred,Tobel, Hans-Rudolf von,Auerbach, Guenther
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p. 1412 - 1419
(2007/10/02)
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- THE SYNTHESIS OF o-NITROBENZENETHIOLS: AN ADVANTAGEOUS NUCLEOPHILIC DISPLACEMENT ON o-CHLORONITROBENZENES
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Reaction of substituted o-chloronitrobenzenes with sodium sulphide in DMSO occurs rapidly and gives the corresponding o-nitrobenzenethiols, following a convenient one-step pathway.Better yields are obtained when stoicheiometric amounts of sulphur, dissolved in a little carbon disulphide, are added in the presence of ethyl methyl ketone as solvent.
- Battistoni, Paolo,Bruni, Paolo,Fava, Gabriele
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p. 301 - 304
(2007/10/02)
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