- Chain carbonylation of methoxymethyl chloride by using AgSbF6 catalyst under high pressure of CO
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The chain carbonylation of methoxymethyl chloride (1) by the use of AgSbF6 catalyst smoothly proceeded under high pressure of carbon monoxide to give methyl methoxyacetate after treatment with methanol. The reaction was highly dependent on the CO pressure and the reaction temperature, indicating the presence of equilibrium processes. From the temperature dependence of the equilibrium constant, the enthalpy change of the reaction was calculated to be -25.4 kJ mol-1.
- Ohga, Yasushi,Netsu, Fuminori,Mori, Sadayuki,Kudo, Kiyoshi,Komatsu, Koichi,Sugita, Nobuyuki
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Read Online
- Heteropolyacid-catalyzed synthesis of chloromethyl methyl ether
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An efficient (in terms of experiment and time) synthetic procedure for chloromethyl methyl ether (MOM-Cl) is described using heteropolyacids as catalysts.
- Kishore, Pilli Satyananda,Viswanathan, Balasubramanian,Varadarajan, Thirukullam Kanthadai
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- Monodisperse microbeads of hypercrosslinked polystyrene for liquid and supercritical fluid chromatography
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Monodisperse styrene-divinylbenzene (1 wt %) copolymer microbeads are obtained via the elaborate method of high-productivity precipitation polymerization. The crosslinking of this copolymer with chloromethyl methyl ether in the presence of Friedel-Crafts catalyst yields porous hypercrosslinked polymers with degrees of crosslinking that range from 200 to 500%. Microbead sorbents are shown to be suited for selective stationary phases for high-performance liquid chromatography and supercritical fluid chromatography.
- Tsyurupa,Blinnikova,Il'In,Davankov,Parenago,Pokrovskii,Usovich
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- Kinetic studies of the oxidation of dimethyl ether and its chain reaction with Cl2
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The reaction between dimethyl ether radicals and molecular oxygen proceeds along two distinct pathways at temperatures between 230 and 350 K. Above about 100 Torr total pressure the peroxy radical, CH3OCH2O2, is predominantly formed. As the pressure is reduced, a channel leading to the formation of OH and two formaldehyde molecules becomes progressively more important. Real time kinetic measurements of these reactions are made using time-resolved UV spectroscopy to monitor CH3OCH2 loss and CH3OCH2O2 formation along with transient IR absorption to probe formaldehyde production. The OH radicals are identified via their UV spectrum. The reaction can be described via a modified Lindemann mechanism using the three parameters kro2,∞, kro2,0, and kprod,0, which represent the high- and low-pressure limits of the O2 addition reaction and the low-pressure limit of the OH/formaldehyde channel. At 295 K they have values of (1.1 ± 0.1) × 10-11 cm3 s-1, (2.6 ± 0.9) × 10-29 cm6 s-1, and (6 ± 2) × 10-12 cm3 s-1, respectively. At Ptot = ~120 Torr the reaction exhibits a negative temperature dependence with kr+o2 = (3.1+1.0-0.8) × 10-12 e(326±80)/T cm3 s-1. Experiments in the absence of oxygen were performed to investigate the CH3OCH2-mediated chain reaction between chlorine and dimethyl ether. Analysis of time-resolved UV spectra reveals rate constants of kr+c12 = (1.8+0.7-0.5) × 10-11 e(360±120)/T cm3 s-1 and kr+r = (1.8+0.6-0.5) × 10-11 e(200±100)/T cm3 s-1, respectively, for the chain propagation reaction between CH3OCH2 and molecular chlorine and for the chain-terminating recombination reaction.
- Maricq, M. Matti,Szente, Joseph J.,Hybl, John D.
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- Synthesis of methoxymethylhexachloroantimonate
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1. A method was developed for the synthesis of methoxymethylhexachloroantimonate, in which connection all of the operations were carried out in vacuo. 2. The decomposition into molecular forms, which is characteristic for MMH solutions, depends to a large degree on the polarity of the medium.
- Komarov,Rozenberg,Enikolopyan
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- A modified low-cost preparation of chloromethyl methyl ether (MOM-Cl)
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The versatile reagent chloromethyl methyl ether (MOM-Cl) is synthesized by using inexpensive starting materials in a large scale. A modification of the existing methods reduces material costs by more than 80%.
- Reggelin, Michael,Doerr, Sebastian
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Read Online
- Synthesis of 1,3-diketo derivatives of calix[4]arene with nonyl substituents at the lower rim as novel efficient sensibilizers of Tb3+ luminescence
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Novel bis- and tetra-1,3-diketo derivatives of calix[4]arene with nonyl substituents at the lower rim have been synthesized. Their conformational and tautomeric composition have been determined; spectral parameters and complex formation properties with Tb3+ have been studied. Substitution of two 1,3-diketo groups with bromine under going from tetra- to bis 1,3-diketone derivatives was resulted in twofold increase luminescence intensity in their terbium complexes. Lifetime of the excited state of the terbium luminescence of the corresponding complexes as well as lifetime of excited triplet level of the 1,3-diketonate ligands have been determined.
- Podyachev,Gimazetdinova, G. Sh.,Sudakova,Lapaev,Syakaev,Nagimov
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- PROCESS FOR PREPARING AN ALKOXYMETHYL ALKYNYL ETHER COMPOUND HAVING A TERMINAL TRIPLE BOND
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The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4):H-CtriplebondC(CH2)aOCH2OCH2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and "a" represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H-CtriplebondC(CH2)aOH (1), wherein "a" is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH2OCH2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH3(CH2)b][CH3(CH2)c]NC6H5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.
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Paragraph 0107-0109; 0119-0121; 0127-0129; 0132-0134; ...
(2021/06/26)
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- PROCESS FOR PREPARING AN ALKOXYMETHYL ALKYNYL ETHER COMPOUND HAVING A TERMINAL TRIPLE BOND
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The present invention provides a process for preparing an alkoxymethyl alkynyl ether compound having a terminal triple bond of the following formula (4): H—C≡C(CH2)aOCH2OCH2R (4), wherein R represents a hydrogen atom, an n-alkyl group having 1 to 9 carbon atoms, or a phenyl group, and “a” represents an integer of 1 to 10, the method comprising subjecting an alkynol compound having a terminal triple bond of the following formula (1): H—C≡C(CH2)aOH (1), wherein “a” is as defined above, to an alkoxymethylation with a halomethyl alkyl ether compound of the following formula (3): RCH2OCH2X (3), wherein X represents a halogen atom, and R is as defined above, in the presence of a dialkylaniline compound of the following formula (2): [CH3(CH2)b][CH3(CH2)c]NC6H5 (2), wherein b and c represent, independently of each other, an integer of 0 to 9, to form the alkoxymethyl alkynyl ether compound (4) having a terminal triple bond.
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Paragraph 0092-0093; 0101-0102; 0107-0108; 0111-0112; ...
(2021/07/02)
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- Fluorine analogs of dicamba and tricamba herbicides; Synthesis and their pesticidal activity
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Fluorine analogs of the dicamba and tricamba herbicides were synthesized. Their herbicide activities were compared with the activities of the pattern herbicides dicamba and tricamba.
- Huras, Bogumi?a,Zakrzewski, Jerzy,Zelechowski, Krzysztof,Kie?czewska, Anna,Krawczyk, Maria,Hupko, Jaros?aw,Jaszczuk, Katarzyna
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p. 181 - 192
(2021/02/27)
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- Synthesis and Antifungal Activity of Chromones and Benzoxepines from the Leaves of Ptaeroxylon obliquum
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This study reports the first total synthesis of the bioactive oxepinochromones 12-O-acetyleranthin (8) (angular isomer) and 12-O-acetylptaeroxylinol (9) (linear isomer). The antifungal activity of these compounds and their derivatives was determined against Candida albicans and Cryptococcus neoformans. Most compounds had good selectivity between the two fungi and showed moderate to good activity. 12-O-Acetyleranthin (8) had the highest activity against C. albicans, with an MIC value of 9.9 μM, while 12-O-acetylptaeroxylinol (9), the compound present in Ptaeroxylon obliquum, had the highest activity against C. neoformans, with an MIC value of 4.9 μM.
- Malefo, Modibo S.,Ramadwa, Thanyani E.,Famuyide, Ibukun M.,McGaw, Lyndy J.,Eloff, Jacobus N.,Sonopo, Molahlehi S.,Selepe, Mamoalosi A.
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p. 2508 - 2517
(2020/09/15)
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- Trisubstituted Imidazoles with a Rigidized Hinge Binding Motif Act As Single Digit nM Inhibitors of Clinically Relevant EGFR L858R/T790M and L858R/T790M/C797S Mutants: An Example of Target Hopping
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The high genomic instability of non-small cell lung cancer tumors leads to the rapid development of resistance against promising EGFR tyrosine kinase inhibitors (TKIs). A recently detected triple mutation compromises the activity of the gold standard third-generation EGFR inhibitors. We have prepared a set of trisubstituted imidazoles with a rigidized 7-azaindole hinge binding motif as a new structural class of EGFR inhibitors by a target hopping approach from p38α MAPK inhibitor templates. On the basis of an iterative approach of docking, compound preparation, biological testing, and SAR interpretation, robust and flexible synthetic routes were established. As a result, we report two reversible inhibitors 11d and 11e of the clinically challenging triple mutant L858R/T790M/C797S with IC50 values in the low nanomolar range. Furthermore, we developed a kinome selective irreversible inhibitor 45a with an IC50 value of 1 nM against the EGFR L858R/T790M double mutant. Target binding kinetics and metabolic stability data are included. These potent mutant EGFR inhibitors may serve as a basis for the development of structurally novel EGFR probes, tools, or candidates.
- Juchum, Michael,Günther, Marcel,D?ring, Eva,Sievers-Engler, Adrian,L?mmerhofer, Michael,Laufer, Stefan
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supporting information
p. 4636 - 4656
(2017/06/13)
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- Mallotojaponins B and C: Total Synthesis, Antiparasitic Evaluation, and Preliminary SAR Studies
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(Chemical Equation Presented). The first total syntheses of mallotojaponin B and C as well as several analogues have been achieved. Biological evaluation of the synthesized compounds against Plasmodium falciparum and Trypanosoma brucei have also been carried out.
- Grayfer, Tatyana D.,Grellier, Philippe,Mouray, Elisabeth,Dodd, Robert H.,Dubois, Jo?lle,Cariou, Kevin
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supporting information
p. 708 - 711
(2016/03/01)
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- Lung Cancer: EGFR Inhibitors with Low Nanomolar Activity against a Therapy-Resistant L858R/T790M/C797S Mutant
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The treatment of non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) inhibitors is made challenging by acquired resistance caused by somatic mutations. Third-generation EGFR inhibitors have been designed to overcome resistance through covalent binding to the Cys 797 residue of the enzyme, and these inhibitors are effective against most clinically relevant EGFR mutants. However, the high dependence of these recent EGFR inhibitors on this particular interaction means that additional mutation of Cys 797 results in poor inhibitory activity, which leads to tumor relapse in initially responding patients. A new generation of irreversible and reversible mutant EGFR inhibitors was developed with strong noncovalent binding properties, and these compounds show high inhibitory activities against the cysteine-mutated L858R/T790M/C797S EGFR.
- Günther, Marcel,Juchum, Michael,Kelter, Gerhard,Fiebig, Heiner,Laufer, Stefan
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supporting information
p. 10890 - 10894
(2016/09/03)
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- A chloromethyl methyl ether and its armor oxygen methyl protection method for the synthesis of the compounds of
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The invention provides chloromethyl methyl ether and a synthesis method of a compound protected by methoxymethyl thereof. The chloromethyl methyl ether (MOMCl) is a common protective reagent in organic synthesis. Commonly used synthesis methods are tedious in operation and long in reaction time. The synthesis method provided by the invention comprises: with trifluoromethane sulfonic acid or perchloric acid as a catalyst, reacting acyl chloride with dimethoxymethane to synthesize the chloromethyl methyl ether. The chloromethyl methyl ether produced in situ can directly act with a hydroxyl compound and organic alkali dissolved in an organic solvent to generate a product with hydroxyl protected by MOM. The method has the advantages of high reaction speed and simple reaction operation. Therefore, the method can be applicable to the production and application of a continuous flow reactor.
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Paragraph 0025; 0026; 0027; 0028
(2016/10/10)
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- TETRAHYDROQUINOLINE COMPOSITIONS AS BET BROMODOMAIN INHIBITORS
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The present invention relates to inhibitors of bromo and extra terminal (BET) bromodomains that are useful for the treatment of cancer, inflammatory diseases, diabetes, and obesity, having Formula (I): wherein W, X, Y, Z, R1, R2, R5, and R8 are as described herein.
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Paragraph 0217
(2015/06/03)
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- The synthesis and analysis of advanced lignin model polymers
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If the lignin-first biorefinery concept becomes a reality, high quality lignins close in structure to native lignins will become available in large quantities. One potential way to utilise this renewable material is through depolymerisation to aromatic chemicals. This will require the development of new chemical methods. Here, we report the synthesis and characterisation of advanced lignin model polymers to be used as tools to develop these methods. The controlled incorporation of the major linkages in lignin is demonstrated to give complex hardwood and softwood lignin model polymers. These polymers have been characterised by 2D HSQC NMR and GPC analysis and have been compared to isolated lignins.
- Lancefield,Westwood
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supporting information
p. 4980 - 4990
(2015/11/16)
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- Facile formation of methylenebis(chalcone)s through unprecedented methylenation reaction. Application to antiparasitic and natural product synthesis
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The formation of methylenebis(chalcone)s has been discovered during deprotection with methoxymethyl groups from trihydroxychalcones. Studies on this methylenation reaction led to a mechanism hypothesis that was extended to other chalcones and to dihydrochalcone, acetophenone, benzophenone and flavone derivatives. This new method was applied to the rapid synthesis of natural product piperanduncin C. These original methylenebis compounds were also evaluated for their antiparasitic activity. Copyright
- Thevenin, Marion,Mouray, Elisabeth,Grellier, Philippe,Dubois, Joelle
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p. 2986 - 2992
(2014/05/20)
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- RESORCINOL COMPOUNDS FOR DERMATOLOGICAL USE
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Provided herein are methods and compositions comprising resorcinol derivatives for the use of treating, regulating or preventing a skin condition characterized by oxidative stress or a degenerative process. Methods of preventing, lightening or reducing the appearance of visible discontinuities of the skin resulting from skin pigmentation, skin aging, or other disorders are also disclosed.
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Paragraph 0124
(2014/09/29)
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- First total synthesis of Boehmenan
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The first total synthesis of dilignan Boehmenan has been achieved. A biomimetic oxidative coupling of the ferulic acid methyl ester in the presence of silver oxide is the crucial step in the synthesis sequence, generating the dihydrobenzofuran skeleton. Hydroxyl group was protected with DHP and reducted with LiAlH 4 to afford the intermediate diol. The diol was condensated with the derivative of ferulic acid, then removed the protecting groups, to get Boehmenan. Meanwhile, a study on the ring-opening reaction of the intermediate dihydrobenzofuran neolignan under base conditions was described.
- Xia, Yamu,Dai, Xiaoli,Liu, Haixin,Chai, Chen
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p. 813 - 820
(2014/07/07)
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- IMPROVED PROCESS FOR THE PREPARATION OF 2-SUSTITUTED-2-(6-(SUBSTITUTED)-7-METHYLBENZO[D][1,3]DIOXOL-4-YL)ACETIC ACID DERIVATIVES
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Present invention relates to an improved and commercial process for the preparation of 2-sustituted-2-(6-(substituted)-7-methylbenzo[d][1,3]dioxol-4-yl)acetic acid derivatives of formula-I [Formula should be inserted here], wherein R1 is a O-protecting group such as methoxymethyl, ethoxymethyl, trialkylsilyl, arylmethyl, tetrahydropyran-2-yl, allyl; X is hydroxyl, halogen, mesylate, triflate, tosylate, acetate; Y is oxygen atom, NH or sulfur atom; R2 is C1-C6 alkyl. 2,4-Dihydroxy-3-methylbenzaldehyde is selectively protected at C-4 position in the form of an ether compound of formula-XII, oxidized the aldehyde function to get the diol of formula-XIII, and condensed with ethyl glyoxalate under Casiraghi reaction conditions to get the compound of formula-XV. Compound of formula-XV is converted to compound of formula-I by conventional chemistry. Compounds of formula-I are key intermediates in the synthesis of ecteinascidines like trabectedin
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Page/Page column 10
(2014/01/09)
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- Total synthesis of the marine antibiotic pestalone and its surprisingly facile conversion into pestalalactone and pestalachloride A
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Surprise, surprise! The total synthesis of the marine natural product pestalone (1), a highly substituted benzophenone with strong antibiotic acitivity, has provided insight into the surprising tendency of this and related molecules to undergo intramolecular Cannizzaro-Tishchenko-type reactions. Pestalone can be readily converted into pestalachloride A, a strongly antifungal metabolite isolated from an endophytic fungus, by simple treatment with ammonia at pH 8.
- Slavov, Nikolay,Cvengros, Jan,Neudoerfl, Joerg-Martin,Schmalz, Hans-Guenther
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supporting information; experimental part
p. 7588 - 7591
(2010/12/25)
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- A systematic study on the activation of simple polyethers by MoCl 5 and WCl6
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MoCl5, 1a, and WCl6, 1b, activate 1,3-dioxolane at room temperature in chlorinated solvents: the compound [MoOCl 3{OC(H)OCH2CH2Cl}]2, 2, has been isolated from MoCl5/dioxolane. The mixed oxo-chloro species WOCl 4, 1c, reacts with 1,3-dioxolane, selectively giving the coordination adduct WOCl4(κ1-C3H6O 2), 3. Dimethoxymethane, CH2(OMe)2, undergoes activation including C-H bond cleavage when reacted with 1a to give the molybdenum complexes [MoOCl3{OC(H)OMe}]2, 4, and Mo 2Cl5(OMe)5, 5. The reactions of 1b with CH 2(OR)2 (R = Me, Et) proceed via O-abstraction with formation of the oxo-derivatives WOCl4[O(R)CH2Cl] (R = Me, 6a; R = Et, 6b) in admixture with equimolar amounts of RCl. The reactions of 1a,b with CMe2(OMe)2 lead to mesityl oxide, MeC(O)CHC(Me)2. A series of simple diethers of general formula ROCH2(CHR′)OR′′ are activated by 1a,b in CDCl 3, usually via cleavage of C-O bonds at high temperature. The complex WCl5(OCH2CH2OMe), 7, has been detected in solution as an intermediate species in the course of the degradation of 1,2-dimethoxyethane (dme) by 1b. The activation of CH(OMe)3 by 1 is limited to C-O bonds and selectively gives methyl chloride and methylformate, which has been found coordinated in WOCl4[OC(H)OMe], 8. The organic fragments produced in the reactions have been detected by GC-MS and NMR analyses, upon hydrolysis of the reaction mixtures. Compounds 2 and 5, which have had their molecular structures ascertained by X-ray diffraction, represent rare examples of crystallographically-characterized dinuclear Mo(v) species containing both halides and oxygen ligands.
- Dolci, Sara,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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experimental part
p. 5367 - 5376
(2010/08/04)
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- The first asymmetric halogen/metal-exchange reaction: Desymmetrization of alcohols with enantiotopic bromoarene substituents
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Desymmetrizations of the prochiral bis(bromoaryl)alcohols 1 and 4 were effected by treatment with iPr2Mg and enantiomerically pure lithium alkoxides. The resulting arylmagnesium compounds were quenched with various electrophiles. The absolute and (if relevant) relative configurations of the resulting products were determined. The best ee/yield combination was obtained for the protonolysis furnishing monobromoalcohol (R)-2 (53% ee, 51% yield). The latter was converted into (R)-orphenadrine, an antihistaminic and anticholinergic drug.
- Saelinger, Daniel,Brueckner, Reinhard
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experimental part
p. 6688 - 6703
(2010/02/28)
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- Synthesis and evaluation of dithiolethiones as novel cyclooxygenase inhibitors
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3H-1,2-Dithiole-3-thiones substituted with a 3,5-di-tert-butyl-4-hydroxyphenyl (DTBHP) or a 3,5-di-tert-butyl-4-methoxyphenyl group at the C5 position were prepared and their ability to inhibit the cyclooxygenase isoenzymes, COX-1 and COX-2 was evaluated. Both compounds were potent inhibitors of COX-2 (relative to rofecoxib), and while the phenol was a weak inhibitor of COX-1, the methyl ether gave no measurable inhibition. Docking studies of the two compounds into the COX-1 and -2 active sites showed that the methyl ether could only fit in the COX-2 active site whereas the phenol could be docked into both COX-1 and -2. This study reports a new mode for inhibitor binding to COX-1 and -2 and a novel structural scaffold for the development of COX-2 selective inhibitors.
- Zanatta, Shannon D.,Manallack, David T.,Jarrott, Bevyn,Williams, Spencer J.
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scheme or table
p. 459 - 461
(2011/03/20)
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- PYRROLE ANTIFUNGAL AGENTS
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The invention provides compounds of formula (I), and pharmaceutically and agriculturally acceptable salts thereof; wherein: R1, R2, R3, R4, R5, R6, A1, L1 and n are as defined herein. These compounds and their pharmaceutically acceptable salts are useful in prevention or treatment of a fungal disease. Compounds of formula (I), and agriculturally acceptable salts thereof, may also be used as agricultural fungicides.
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Page/Page column 107
(2009/12/05)
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- Synthesis and fate of o-carboxybenzophenones in the biosynthesis of aflatoxin
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o-Carboxybenzophenones have long been postulated to be intermediates in the oxidative rearrangement of anthraquinone natural products to xanthones in vivo. Many of these Baeyer-Villiger-like cleavages are believed to be carried out by cytochrome P450 enzymes. In the biosynthesis of the fungal carcinogen, aflatoxin, six cytochromes P450 are encoded by the biosynthetic gene cluster. One of these, AflN, is known to be involved in the conversion of the anthraquinone versicolorin A (3) to the xanthone demethylsterigmatocystin (5) en route to the mycotoxin. An aryl deoxygenation, however, also takes place in this overall transformation and is proposed to be due to the requirement that an NADPH-dependent oxidoreductase, AflM, be active for this process to take place. What is known about other fungal anthraquinone → xanthone conversions is reviewed, notably, the role of the o-carboxybenzophenone sulochrin (25) in geodin (26) biosynthesis. On the basis of mutagenesis experiments in the aflatoxin pathway and these biochemical precedents, total syntheses of a tetrahydroxy-o-carboxybenzophenone bearing a fused tetrahydrobisfuran and its 15-deoxy homologue are described. The key steps of the syntheses entail rearrangement of a 1,2-disubstituted alkene bearing an electron-rich benzene ring under Kikuchi conditions to give the 2-aryl aldehyde 43 followed by silyltriflate closure to a differentially protected dihydrobenzofuran 44. Regiospecific bromination, conversion to the substituted benzoic acid, and condensation with an o-bromobenzyl alcohol gave esters 47 and 50. The latter could be rearranged with strong base, oxidized, and deprotected to the desired o-carboxybenzophenones. These potential biosynthetic intermediates were examined in whole-cell and ground-cell experiments for their ability to support aflatoxin formation in the blocked mutant DIS-1, defective in its ability to synthesize the first intermediate in the pathway, norsolorinic acid. Against expectation, neither of these compounds was converted into aflatoxin under conditions where the anthraquinones versicolorin A and B readily afforded aflatoxins B1 and B2. This outcome is evaluated further in a companion paper appearing later in this journal.
- Henry, Kevin M.,Townsend, Craig A.
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p. 3300 - 3309
(2007/10/03)
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- Simple, rapid procedure for the synthesis of chloromethyl methyl ether and other chloro alkyl ethers
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Zinc(II) salts catalyze the reaction between acetals and acid halides to provide haloalkyl ethers in near-quantitative yield. Reactions from millimole to mole scale are typically complete in 1-4 h with 0.01 mol % catalyst. The solutions of haloalkyl ethers thus obtained can be utilized directly in reactions in which the presence of the ester byproduct does not interfere. Excess haloalkyl ether is destroyed on workup, thereby minimizing exposure to this class of carcinogenic compounds.
- Berliner, Martin A.,Belecki, Katherine
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p. 9618 - 9621
(2007/10/03)
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- Discovery and optimization of new chromium catalysts for ethylene oligomerization and polymerization aided by high-throughput screening
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High throughput screening (HTS) of a 205 member Schiff base salicylaldimine ligand library derived from salicylaldehydes bearing bulky ortho-substituents, i.e., 9-anthracenyl, 1,4,5,8-tetramethylanthracenyl or triptycenyl, reacted in-situ with (p-tolyl)CrCl2(thf)3, identified two new classes of highly active chromium based systems for the Oligomerization and polymerization of ethylene, respectively. The polymerization system comprises bidentate ortho-substituted anthracenyl Schiff bases bearing small primary or secondary alkyl imine substituents. The Oligomerization catalysts are based upon tridentate orthotriptycenyl-substituted Schiff bases with pyridylmethyl or quinolyl substituents. Validation tests confirmed polymerization productivities of up to 3000 g·mmol-1h-1bar-1 for the polymerization catalyst systems while the oligomerization catalysts gave productivities up to 10 000 g·mmol-1h-1bar -1. Key catalyst precursors have been characterized by X-ray crystallography.
- Jones, David J.,Gibson, Vernon C.,Green, Simon M.,Maddox, Peter J.,White, Andrew J. P.,Williams, David J.
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p. 11037 - 11046
(2007/10/03)
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- Preparation of chloromethyl methyl ether revisited
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Chloromethyl methyl ether (MOMCl) may be prepared in high yield from decanoyl chloride and dimethoxymethane in the presence of H2SO4.
- Chong, J. Michael,Shen, Lixin
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p. 2801 - 2806
(2007/10/03)
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- Electrophilic Aromatic Substitution. 13.1 Kinetics and Spectroscopy of the Chloromethylation of Benzene and Toluene with Methoxyacetyl Chloride or Chloromethyl Methyl Ether and Aluminum Chloride in Nitromethane or Tin Tetrachloride in Dichloromethane. the Methoxymethyl Cation as a Remarkably Selective Common Electrophile
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Vacuum line kinetics studies have been made of the reaction in nitromethane between benzene and/or toluene, methoxyacetyl chloride (MAC), and AlCl3 to produce benzyl or xylyl chlorides, CO, and a CH3OH- AlCl3 complex. For both arenes, the rate law appears to be R = (k3/[AlCl3]0) [AlCl3]2-[MAC]. When chloromethyl methyl ether (CMME) is substituted for MAC, a similar rate law is obtained. Both chloromethylation reactions yielded similar, large kT/kB ratios (500-600) and similar product isomer distributions with low meta percentages (~0.4) which suggest CH3OCH2+ or the CH3OCH2+Al2Cl7 - ion pair as a common, remarkably selective, electrophile. The kinetics of MAC decomposition to CMME and CO in the presence of AlCl3 yielded the rate law R = k2[AlCl3]0[MAC]. Here AlCl3 is a catalyst (no CH3OH is formed), and thus the rate law is equivalent to the chloromethylation rate law. All three reactions have comparable reactivities, which is consistent with rate-determining production of the electrophile. Kinetics studies of benzene or toluene with SnCl4 and MAC or CMME in dichloromethane were also completed. With MAC and benzene the rate law is R = k3[SnCl4]0[MAC][benzene] and with toluene R = k2[SnCl4]0[MAC]. MAC decomposition, again followed by CO production, was unaffected by the presence of either aromatic and obeyed the rate law R = k2′ [SnCl4]0[MAC] where k2 ≈ k2′ Chloromethylation with CMME followed the rate law R = k3[SnCl4]0[CMME][arene] for benzene and toluene and produced a kT/kB ratio and product isomer distributions very similar to those determined with AlCl3 in nitromethane, further supporting a common electrophile. Low-temperature 13C and 119Sn FT-NMR and Raman spectroscopic studies suggest the existence of a weak 1:1 adduct between MAC and SnCl4 of the type RCXO → SnCl4, with electron donation to the metal through carboxy oxygen. Finally, an explanation is provided for the range of chloromethylation kT/kB values and product isomer percentages published in the literature.
- Dehaan, Franklin P.,Djaputra, Markus,Grinstaff, Mark W.,Kaufman, Craig R.,Keithly, James C.,Kumar, Amit,Kuwayama, Mark K.,Dale Macknet,Na, Jim,Patel, Bimal R.,Pinkerton, Michael J.,Tidwell, Jeffrey H.,Villahermosa, Randy M.
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p. 2694 - 2703
(2007/10/03)
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- Far-IR spectra, barriers to internal rotation, r0 structural parameters and ab initio calculations of chloromethyl methyl ether
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The far-IR spectra from 350 to 50 cm-1 of gaseous chloromethyl methyl ether, ClCH2OCH3, along with three of the deuterium isotopomers, have been recorded at a resolution of 0.10 cm-1.The fundamental asymmetric torsional and methyl torsional modes are extensively mixed and have been observed at 180 and 133 cm-1, respectively.An estimate is given for the potential function governing the asymmetric torsion.On the basis of a one-dimensional model the barrier to internal rotation of the methyl moiety is determined to be 556 +/- 5 cm-1 (1.59 +/- 0.01 kcal mol%-1).Utilizing previously reported rotational constants for seven isotopomers, r0 structural parameters are determined.The heavy atom parameters (distances in angstroems angles in degrees) are: r(C1-Cl) = 1.818 +/- 0.003; r(C1-O) = 1.371 +/- 0.004; r(C&2-O) = 1.430 +/- 0.001; ClC1O = 113.01 +/- 0.07; C1OC2 = 114.03 +/- 0.10 and dihedral ClC1OC2 = 70.20 +/- 0.15.A complete vibrational assignment is given for the ClCD2OCD3 molecule.The fundamental vibrational frequencies, barrier to internal rotation and structural parameters which have been obtained experimentally are compared with those obtained from ab initio Hartree-Fock calculations employing the 3-21G* and 6-31G* basis sets along with the 6-31G* basis set with electron correlation at the MP2 level.All of these results are discussed and compared with the corresponding quantities obtained for some similar molecules.
- Guirgis, G. A.,Veken, B. J. van der,Liu, Jian,Durig, J. R.
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p. 1947 - 1966
(2007/10/02)
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- Dual Reactivity of Methoxymethyl Benzenesulfonate in Nucleophilic Substitution
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Hydrolysis of methoxymethyl benzenesulfenate is catalyzed by both acid and base.Acid-catalyzed hydrolysis is further accelerated by various nucleophiles like halide ions, thiocyanate, dialkyl sulfide, and the substrate itself.The catalytic constants coincide with those for ethyl benzenesulfenate within 2-fold in magnitude.The nucleophilic reactivity strongly suggests the reaction at the sulfenyl sulfur, but examination of the products from the 18O-labeled substrate showed that the bond cleavage occurs mostly between the oxygen and the proformyl carbon except for the acid-catalyzed water reaction which undergoes the S-O cleavage.A mechanism for a nucleophilic reaction at the sulfur to form a sulfurane intermediate which breaks down with the C-O cleavage is presented.The hydrolysis rate is also strongly dependent on the second order of buffer concentrations in carboxylate and tertiary amine buffer solutions.The third-order term involves both the general acid and the conjugate base of the buffer, and the latter reacts at the sulfur as a nucleophile in the rate-determining step but leads to the C-O cleavage in the same way as the other catalytic nucleophiles.
- Okuyama, Tadashi,Fueno, Takayuki
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p. 2672 - 2683
(2007/10/02)
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- Cross Aldol Products from α-Haloalkoxysilanes and Silyl Enol Ethers
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α-Haloalkoxysilanes have been prepared by cleavage of the C-S bond in O,S-acetals with sulfuryl chloride, and by cleavage of C-Sn bond in α-silyloxystannanes by bromine.The α-haloalkoxysilanes, both after isolation or after preparation in situ react with silyl enol ethers to yield silyl-protected cross aldol products.The reaction is catalyzed by Lewis acids.
- Antonsen, Oeyvind,Benneche, Tore,Gundersen, Lise-Lotte,Undheim, Kjell
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p. 172 - 177
(2007/10/02)
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- Intramolecular Catalysis of the Hydrolysis of an Acetal by an Internally Hydrogen-bonded Hydroxy Group
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The hydrolysis of 1-methoxymethoxy-8-hydroxynaphthalene in aqueous solution at pH 2-4 is catalysed by the hydronium ion and the value of the catalytic coefficient is similar to that for 1-methoxymethoxynaphthalene.In the range pH 5-10 a pH-independent reaction with solvent is dominant and the rate coefficient for the neutral hydrolysis is estimated to be ca. 40-fold higher for 1-methoxymethoxy-8-hydroxynaphthalene than for 1-methoxymethoxynaphthalene.This is attributed to intramolecular catalysis by the hydrogen-bonded hydroxy group.As bond breakage and charge development occur in the transition state the internal hydrogen bond in the leaving group is strengthened.
- Hibbert, Frank,Spiers, Karen J.
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p. 377 - 380
(2007/10/02)
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- SULFURIC ACID CATALYZED DECARBONYLATION OF ALKOXYACETYL CHLORIDES
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Sulfuric acid catalyzes the decarbonylation of alkoxyacetyl chlorides to produce the corresponding chloromethyl alkyl ethers in fairly good yields.
- Basavaiah, D.,Rao, P. Dharma,Gowriswari, V. V. L.
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p. 1411 - 1414
(2007/10/02)
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- Mechanism of Reactions of N-(Methoxymethyl)-N,N-dimethylanilinium Ions with Nucleophilic Reagents
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The prediction that the oxocarbonium ion derived from formaldehyde should have a "lifetime" of ca. 10-15 s that gives rise to an enforced preassociation or concerted reaction mechanism has been tested by examining the reactions of N-(methoxymethyl)-N,N-dimethylanilinium ions in water in the presence of added nucleophilic reagents.These compounds undergo well-behaved second-order reactions with nucleophiles and give the amount of substitution product that is expected from the rate increase in the presence of nucleophile.Structure-reactivity correlations exhibit behavior intermediate between that expected for SN2 (Swain-Scott) and carbonium ion (N+) reactions.The small values of s = 0.3 and βnuc = 0.14 and large values of β1g = -0.7 to -0.9 indicate a transition state that can be described either as an open transition state for SN2 displacement or as an oxocarbonium ion that is stabilized by weak interactions with the entering and leaving groups.Secondary α-deuterium isotope effects for the second-order reactions range from (kH/kD)/D = 0.99 for fluoride ion to 1.18 for iodide ion.Solvolysis and the second-order reaction with n-propylamine exhibit values of ΔS(ex) = -1.2 and -2.1 cal K-1 mol-1, respectively, and display similar changes in rate in mixed water-alcohol solvents.It is suggested that the lifetime of the carbonium ion species in the presence of nucleophiles is so short that the reaction mechanism must be concerted.
- Knier, Barry L.,Jencks, William P.
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p. 6789 - 6798
(2007/10/02)
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- Polyene compounds
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Novel 9-substituted or unsubstituted thienyl-3,7-dimethyl-nona-2,4,6,8-tetraene derivatives, useful as antitumor agents as well as processes for their preparation and novel intermediates are disclosed.
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