Search results for "Yield"
showing 10 items of 1338 documents
Synthesis of (+)-pechueloic acid and (+)-aciphyllene. Revision of the structure of (+)-aciphyllene
2007
Abstract 1α H ,7α H ,10α H -Guaia-4,11-dien-3-one and its 1β H ,10β H diastereomer, easily obtained from (+)-dihydrocarvone, are good starting materials for the synthesis of natural guaiane derivatives. Allylic oxidation of the 1α H ,10α H isomer gave as main product its 13-hydroxy derivative and a small amount of (+)-7β-hydroxy-1α H ,10α H -guaia-4,11-dien-3-one, whereas the 1β H ,10β H diastereomer afforded selectively the (−)-7α-hydroxy-1β H ,10β H enantiomer in excellent yield. From the 13-hydroxy derivative (+)-pechueloic acid and (+)-methyl pechueloate were synthesized. Deoxygenation at C 3 of the 1β H ,10β H guaiadienone afforded a guaiadiene with the reported structure for aciphylle…
Influence of operational variables on the photodegradation kinetics of Monuron in aqueous titanium dioxide dispersions
1994
The degradation of Monuron [N′—(4-chlorophenyl)—N, N dimethyl urea] in aqueous TiO 2 dispersions irradiated in the near-UV region has been investigated using a Pyrex batch photoreactor. The influence on the degradation kinetics of pH, initial Monuron concentration and catalyst concentration has been studied. The mineralization of the pollutant was also investigated. Measurements of photon absorbed flows allowed to determine the quantum yield values; they were found to increase by increasing the initial pH of the dispersion.
Giant Crown-Shaped Polytungstate Formed by Self-Assembly of CeIII-Stabilized Dilacunary Keggin Fragments
2010
Single crystals of Na40K6[Ni(H2O)6]3 [K@K7Ce24Ge12W120O456 (OH)12(H2O)64]· 178H2O are synthesized by addition of KCl to a NaOAc/AcOH buffer solution containing Ce(NO3)3, GeO2, Na2WO4, and NiCl2 followed by slow evaporation at room temperature (24% yield).
Versuche zur umsetzung von methylendiphenolen mit glucosederivaten und zur kondensation von O-phenylglucosidderivaten
1981
Attempts to apply known methods of glucosidation to oligo[(hydroxyphenylene)methylene]s were not satisfying. The reaction of 4,4'-dimethyl-2,2'-methylenediphenol (1a) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide gave a monoglucoside in 11% yield. A second attempt, the condensation of suitable O-phenylglucoside derivatives was unsuccessful. From a series of O-phenylglucosides (4) only 4-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyloxy)benzylbromide could be condensed with O-(4-hydroxymethylphenyl)-2,3,4,6-tetra-O-acetylglucopyranose to the corresponding diglucoside of 4,4'-oxydimethylenediphenol (7). Condensation reactions of the O-phenylglucoside 4k, to obtain an O-glucosidized poly[…
5,6,7-Trimethoxy-2,3-dihydro-1H,8H-benzo[a]pyrrolo[3,4-c]carbazole-1,3-dione dimethyl sulfoxide solvate
2005
The crystal structure of the title compound, C21H16N2O5·C2H6OS, was determined to investigate the electrocyclic reactivity of 3,4-diaryl-1H-pyrrole-2,5-diones (3,4-bisarylmaleimides) to the yield corresponding carbazole derivatives.
Synthese von Cyclo-urethanen
1962
Die Bis-chlorkohlensaureester einiger Oligoathylenglykole HO—(CH2CH2O)nH (n = 1–6) wurden mit Hexamethylendiamin, m-Toluylendiamin bzw. p-Phenylendiamin zu den entsprechenden Cyclodi-urethanen umgesetzt. Die Ausbeute in Abhangigkeit von der Ringgrose ergibt ein Maximum bei einer Ringgliederzahl von etwa 17. Ebenso wird die katalysierte Reaktion von Diisocyanaten mit Diolen zur Darstellung von Cyclo-urethanen benutzt. In Gegenwart von Di-n-butylzinndilaurat werden Austauschreaktionen sowohl zwischen Hydroxylendgruppen und Urethangruppen als auch zwischen Urethangruppen beobachtet. The bis-chlorocarbonates of some oligo-ethylene glycols HO—(CH2CH2O)nH (n = 1–6) were reacted with hexamethylene…
6-Amino-7-Azaindoles synthesis from 2,6-diamino pyridine and diols
2021
Abstract 6-Amino-7-azaindole has been prepared by combination of diaminopyridine and diols by means of an acceptorless dehydrogenative condensation. In addition, amino pyridines may also yield towards pyrrolo[3,2-b]pyrrole systems. All of these transformation have been performed with accessible heterogeneous catalysts: Pd/C and ZnO.
Efficient palladium catalyzed synthesis of heteroaromatic sulfoxides
2007
Abstract The present Letter describes the efficient synthesis of novel heteroaromatic sulfoxides by means of a palladium catalyzed heteroarylation of sulfenate anions. Triazolopyridine, pyridine and thiophene sulfoxides can be obtained under mild conditions and in high yield from the corresponding heteroaryl bromides.
Leaving Group and Regioselectivity Switches in the Aminoalkylation Reaction of Indoles and Related Heterocycles with α-Amido Sulfones
2013
The regioselective aminoalkylation of indoles and related heterocycles with α-amido sulfones under basic conditions has been studied. The reaction that employed the MeMgBr/MgBr2 system provided high yields of 3-(1-carbamoylalkyl)indoles. On the other hand, the reaction that used Cs2CO3 afforded 1-(1-carbamoylalkyl)indoles exclusively in high yields. The first reaction constitutes a switch of the leaving group of the α-amido sulfone in comparison to previously reported reactions between indoles and α-amido sulfones, which provided 3-(1-arylsulfonylalkyl)indoles. The second reaction constitutes a switch in the regioselectivity. The extensions of these C- and N-aminoalkylations starting from p…
Pyrrole Studies. Part 40.1Synthesis of 2- and 3-Substitoted 1-Methylindoles from Vinylpyrroles.
1988
Abstract 4-Substituted-2-vinylpyrroles are more reactive than 2-substituted-4-vinylpyrroles in their reaction with DMAD to yield, respectively, 6/7- and 4,5-dihydroindoles, which are readily dehydrogenated to give indoles possessing electron-withdrawing substitutents at the 3- and 2-positions.