共查询到20条相似文献,搜索用时 15 毫秒
1.
Pews-Davtyan A Tillack A Ortinau S Rolfs A Beller M 《Organic & biomolecular chemistry》2008,6(6):992-997
Improved palladium catalysts for the Suzuki coupling of 3-bromo-1-methyl-4-(2-methyl-3-indolyl)maleimide have been developed. The coupling of both aryl- and heteroarylboronic acids proceeds smoothly in good to excellent yields at low catalyst loading. 相似文献
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A novel synthesis of 2-aryl-2H-indazoles via a palladium-catalyzed intramolecular amination reaction
[reaction: see text] A variety of 2-aryl-2H-indazoles were synthesized by the palladium-catalyzed intramolecular amination of the corresponding N-aryl-N(o-bromobenzyl)hydrazines. Of several sets of reaction conditions surveyed, the combination of Pd(OAc)2/dppf/tBuONa gave the best results. This method applies to a wide scope of substrates containing electron-donating and electron-withdrawing substituents. 相似文献
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Adri van den Hoogenband Jos H.M. Lange Wouter I. Iwema-Bakker Jack A.J. den Hartog Jord van Schaik Rolf W. Feenstra Jan Willem Terpstra 《Tetrahedron letters》2006,47(26):4361-4364
An unprecedented synthetic approach to novel 4-aryl-1-methyloxindoles is described. The method involves the intramolecular palladium-catalyzed amidation of N-methyl-2,6-dibromophenylacetamide followed by an in situ Suzuki cross-coupling reaction with a (hetero)arylboronic acid in a one-pot reaction. 相似文献
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The Heck coupling of haloarenes with various alkenes was successfully performed in the presence of 0.5 mole % Pd(OAc)2 and 1.0 mole % d-glucosamine as an additive with K2CO3 as the optimal base in a mixture of H2O/iPrOH (φ r = 2: 1) as the reaction solvent at 80°C after 6 h. d-Glucosamine was found to be an inexpensive, air-stable, easy to available, and efficient additive in palladium-catalyzed Heck reactions of aryl iodides (67–95 % conversion) and bromides (38–72 % conversion). 相似文献
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Trideep Rajale Shikha SharmaDaniel A. Stroud Daniel K. Unruh Emily MiaouKimberly Lai David M. Birney 《Tetrahedron letters》2014
An efficient Pd-catalyzed Suzuki cross-coupling reaction of sterically crowded 4-chlorocoumarin derivatives with air- and moisture-stable potassium organotrifluoroborates is developed. This methodology has been used to generate a series of novel alkyl, aryl, and vinyl substituted coumarin derivatives in good to excellent yields. The twisted conformation of the vinyl groups in the X-ray crystal structures of (2-oxo-4-vinyl-2H-chromen-3-yl)methyl acetate (2) and (2-oxo-4-vinyl-2H-chromen-3-yl)methyl 2,2,2-trichloroacetimidate (3), along with the atropisomerism of 3-(hydroxymethyl)-4-(2-methoxyphenyl)-2H-chromen-2-one (1d), are evidence of the steric crowding in these adducts. 相似文献
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A simple and novel method to the synthesis of 3-fluoro-4-aryl-2-pyridone from a Michael-adduct of fluoronitroacetate and α,β-unsaturated ketone is reported. With (NH4)2CO3 as the N-source and TsOH as the promoted acid, a series of fluorinated-pyridones was obtained with moderate to good yields. 相似文献
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[reaction: see text] The formation of 2-aminobenzimidazoles via intramolecular C[bond]N formation between an aryl halide and a guanidine moiety can be achieved using either copper or palladium catalysis. Inexpensive copper salts such as CuI are generally superior to the use of palladium catalysts. Regioselective cyclizations, where R(3) = H, can be achieved in high yield under CuI/1,10-phenanthroline-catalyzed conditions, whereas palladium catalysis results in the formation of regioisomeric products. 相似文献
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N,N-Dimethyl-beta-alanine was found to be a more powerful phosphine-free ligand than the previously reported ligand, N,N-dimethylglycine, in the Pd-catalyzed Heck reaction for a variety of aryl bromides, aryl iodides, and activated aryl chlorides with a practical turnover number of 10(3). Both kinetic and theoretical studies suggested that N,N-dimethyl-beta-alanine led to faster oxidative addition of an aryl halide to Pd than N,N-dimethylglycine. [reaction: see text] 相似文献
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A new synthesis of 4-carbamoyl-3-hydroxycoumarin is reported. The synthesis of carbanilates of 3-hydroxycoumarin and their novel rearrangement to the carboxamides is also described. 相似文献
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An inexpensive and highly efficient Pd(OAc)(2)/Dabco catalytic system has been developed for the cross-coupling of aryl halides with arylboronic acids. A combination of Pd(OAc)(2) and Dabco (triethylenediamine) was observed to form an excellent catalyst, which affords high TONs (turnover numbers; TONs up to 950 000 for the reaction of PhI and p-chlorophenylboronic acid) for Suzuki-Miyaura cross-coupling of various aryl iodides and bromides with arylboronic acids. [reaction: see text] 相似文献
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A new one-pot room-temperature palladium-catalyzed synthesis of 7-aryltetralones was discovered. This tandem process includes a palladium-catalyzed gamma-selective arylation of the enone 4 followed by a dehydrogenation-aromatization of the initial cross-coupling product. [reaction: see text] 相似文献
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[formula: see text] A novel type of palladium-catalyzed cascade cyclization-coupling reaction that proceeds with suppressed beta-hydride elimination has been found. One of the N-sulfonyl oxygens is suggested to coordinatively stabilize an alkylpalladium intermediate, thus preventing the intermediate from the usual beta-elimination. This is the first sequential palladium-catalyzed coupling reaction where the Suzuki and Heck reactions can compete. The reaction provides an efficient synthetic route to 4-methylene-3-arylmethylpyrrolidines, which are not readily available by other routes. 相似文献
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A novel phosphine-catalyzed intermolecular [3 + 2] cycloaddition of ynones and N-substituted isatins was developed. In this reaction, substituted ynones, serving as a C(3) synthon, were successfully applied in intermolecular annulation reactions. A number of functionalized spirooxazolines were obtained in high yields and stereoselectivity. 相似文献
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Treatment of pyridine-2-carboxaldehyde with activated alkenes such as alkyl vinyl ketones and cyclic enones in the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides a novel facile one-pot synthesis of indolizine derivatives, thus for the first time describing an electrophile induced Baylis-Hillman reaction. 相似文献
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Results of the detailed investigations on the bromination of the methyl group of 3-aryl-5-methyl-isoxazole-4-carboxylate, a precursor to obtain 3-aryl-5-formyl-isoxazole-4-carboxylate, are described. The products generated during the study have been utilized as substrates for the synthesis of isoxazole-fused heterocycles. 相似文献
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Mehdi Adib Mohammad Mahdavi Farzad Malihi Hamid Reza Bijanzadeh 《Tetrahedron letters》2009,50(52):7246-3194
A novel synthesis of 5-(alkylamino)-4-aryl-3-isoxazolecarboxamides is described. Heating a mixture of an isocyanide and a nitrostyrene in water afforded the title compounds in excellent yields. 相似文献