- Synthesis of Vicinal Quaternary All-Carbon Centers via Acid-catalyzed Cycloisomerization of Neopentylic Epoxides
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We report our studies on the development of a catalytic cycloisomerization of 2,2-disubstituted neopentylic epoxides to produce highly substituted tetralins and chromanes. Termination of the sequence occurs via Friedel-Crafts-type alkylation of the remote (hetero)arene linker. The transformation is efficiently promoted by sulfuric acid and proceeds best in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as the solvent. Variation of the substitution pattern provided detailed insights into the migration tendencies and revealed a competing disproportionation pathway of dihydronaphthalenes.
- Schmid, Matthias,Sokol, Kevin R.,Wein, Lukas A.,Torres Venegas, Sofia,Meisenbichler, Christina,Wurst, Klaus,Podewitz, Maren,Magauer, Thomas
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supporting information
p. 6526 - 6531
(2020/09/02)
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- NOVEL NEISSERIA MENINGITIDIS SEROGROUP Y OLIGOMER AND PROCESS FOR SYNTHESIZING THEREOF
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The present invention relates to novel oligomers of Neisseria meningitidis serogroup Y capsular polysaccharide repeating unit (Men-Y oligomers) and process for synthesizing novel Men- Y oligomers. Inparticular, the present invention relates to the chemical synthesis of the tetramer of Men- Y capsular polysaccharide repeating unit capable of being used as a candidate in the development of semisynthetic or fully synthetic conjugate vaccine against meningococcal serogroup Y bacterial infection.
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Paragraph 0055; 0056; 0057; 0059; 0060
(2018/04/03)
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- Preparation method of climbazole
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The invention discloses a preparation method of climbazole. According to the method, toluene, chloroetherketone, imidazole and a catalyst, serving as raw materials, react under 100 DEG C to 110 DEG Cfor 4 hours while the temperature is kept, and then the climbazole with the purity being up to 99 percent is prepared by methods, such as crystallization, purification, alkaline wash and recrystallization. Through a lot of experiments, the invention screens out the best climbazole preparation method, the whole process design is reasonable, the process is easy and efficient to operate, in particular, the best reaction conditions screened out, which include catalyst variety, reaction solvent, reaction temperature, reaction time and steps, such as crude reaction of methylbenzene and the climbazole, and alkaline wash thereof, can greatly increase reaction yield (up to 92 percent or above), side reaction is reduced, the reaction rate is increased, the production cost is greatly reduced, and therefore the preparation method of the climbazole has a good application prospect.
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Paragraph 0055; 0056; 0057; 0059; 0060
(2018/04/03)
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- Photodegradation of Azole Fungicide Triadimefon
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To examine the photostability of the fungicide triadimefon [1-(4-chlorophenoxy)-3,3-dimethyl-1H-(1,2,4-triazol-1-yl)butan-2-one] in the field, model experiments with organic solvents were performed. Photolysis in methanol, hexane, and acetone resulted in considerable formation of 1-(4-chlorophenoxy)-3,3-dimethylbutan-2-one, 1-[(4-chlorophenoxy)methyl]-1H-1,2,4-triazole, 1H-(1,2,4-triazol-1-yl)-3,3-dimethylbutan-2-one, and 1-phenoxy-3,3-dimethyl-1H-(1,2,4-triazol-1-yl)butan-2-one. The rate of photodegradation in different solvents followed first-order rate kinetics with a significant correlation coefficient.
- Nag, Subir K.,Dureja, Prem
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p. 294 - 298
(2007/10/03)
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- Phototransformation of triadimefon on glass and soil surfaces
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Photodegradation of triadimefon has been studied on glass and soil surfaces. A number of photoproducts have been isolated and characterised by NMR, IR and MS. Photolysis resulted in considerable amounts of 1-(4- chlorophenoxymethyl)-1,2,4-triazole, 1-(4-chlorophenoxy)-2,2-dimethyl-1- (1,2,4-triazol-1-yl)propane, 1-(1,2,4-triazol-1-yl)-3,3-dimethylbutan-2-one and 1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-ol. Rates of photodegradation on glass and soil surfaces under UV and sunlight followed first-order kinetics with a significant correlation coefficient. Photodegradation was greater on alluvial soil than on laterite soil.
- Nag,Dureja
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p. 247 - 252
(2007/10/03)
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- Synthesis, X-ray Structure and Reactions of (2-Oxoalkyl)triarylbismuthonium Salts
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Treatment of triarylbismuth difluorides 1 with silyl enol ethers 2 in the presence of boron trifluoride-diethyl ether or trimethylsilyl trifluoromethanesulfonate (triflate) gave (2-oxoalkyl)triarylbismuthonium tetrafluoroborates 3 and triflates 4 in good yields.A similar reaction of the difluorides 1 with hexamethyldisiloxane in the presence of the latter acid reagent led to the formation of oxybis(triarylbismuth) ditriflates 5.X-Ray crystallographic analyses of compounds 3a, 4a and 5a showed that the first two onium salts have a distorted tetrahedral geometry and the last, a μ-oxo type compound, has a distorted trigonal bipyramidal geometry around the bismuth centre.The stability of these bismuthonium salts may reasonably be attributed to the intramolecular coordinative interaction between the bismuth and oxygen atoms and also low nucleophilicity of the counter ions employed.The bismuthonium salt 3f readily underwent onium exchange with the phosphine 6 and the sulfide 9 to afford the corresponding phosphonium and sulfonium salts 7 and 10.The salts 3 and 4 also underwent coupling with a variety of nucleophiles such as the enolate 11, piperidine 13, the phenoxides 15, the thiolates 17, the sulfinate 19 and the halides 21 to afford the corresponding α-substituted ketones 12, 14, 16, 18, 20 and 22 in moderate to good yields, together with a good recovery of triphenylbismuthine 8.
- Matano, Yoshihiro,Azuma, Nagao,Suzuki, Hitomi
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p. 1739 - 1748
(2007/10/02)
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- Fungicidal imidazol-1-yl-carboxylic acid ester derivatives
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This invention provides an imidazol-1-yl-carboxylic acid ester derivative represented by the formula STR1 wherein R1 is lower alkyl, cycloalkyl or R3 (CH3)2 C--(wherein R3 is halogenomethyl, acyloxymethyl or alkoxycarbonyl), R2 is a hydrogen atom, lower alkyl or cycloalkyl, X is a hydrogen atom, halogen atom, lower alkyl, cycloalkyl, lower alkenyl, lower alkoxyl, lower alkenyloxy, lower alkynyloxy, lower alkylthio, haloalkyl, haloalkenyl, substituted or unsubstituted phenyl, substituted or unsubstiuted benzyl, substituted or unsubstituted phenoxy, nitro, cyano, --COR4 l (wherein R4 is lower alkoxyl, lower alkenyloxy, benzyloxy, lower alkylamino or anilino)or STR2 (wherein R5 and R6 are each lower alkyl, acyl, sulfonyl or lower alkoxycarbonyl), n is an integer of from 1 to 3, Y and Z are the same or different and are each an oxygen atom or sulfur atom, a is 0 or 1, and b is 1 or 2, process for preparing the derivative, and a fungicidal composition comprising the derivative as an active component.
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- Preparation of 1-aryloxy-methyl ketones
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A process for the preparation of a 1-aryloxy-methyl ketone of the formula STR1 in which R1, R2 and R3 each independently is hydrogen, optionally substituted alkyl, alkenyl, alkynyl or optionally substituted aryl, or R1 and R2 together are an alkylene chain, R4 each independently is halogen, alkyl, alkoxy, optionally substituted aryl or nitro, and n is 0, 1, 2 or 3, comprising hydrolyzing a 1-halogeno-2-aryloxy-1-alkene of the formula STR2 in which Hal is chlorine or bromine, under acidic conditions at a temperature from about 20° to 150° C. until it is about 95 to 100% complete, adding a base, and then bringing the reaction to completion under weakly alkaline conditions at about 20° to 150° C. Advantageously all stages of the reaction are effected in a single vessel at a temperature from about 40° to 100° C. and in the presence of an inert organic solvent, optionally in admixture with water as a solution or as a two-phase system, about 1 mol of a monobasic acid and 2 mols of alkali metal carbonate being employed per mol of the 1-halogeno-2-aryloxy-1-alkene. The end products are known intermediates for fungicides.
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- Preparation of 3,3-dimethyl-1-phenoxy-butan-2-ols as fungicide intermediates
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3,3-Dimethyl-1-phenoxy-butan-2-ols of the formula STR1 in which Y is a halogen atom, an optionally substituted phenyl radical, an optionally substituted phenoxy radical or a nitro, cyano, alkyl, alkoxy, alkoxycarbonyl or cycloalkyl radical, and n is 0, 1, 2 or 3, exhibit plant growth stimulating properties and are also useful in the synthesis of known fungicides. They are produced from tert-butyloxirane and the corresponding phenols.
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