共查询到20条相似文献,搜索用时 15 毫秒
1.
Sandeep Chaudhary 《Tetrahedron letters》2009,50(20):2437-1681
We have investigated the use of microwaves in a direct biaryl coupling reaction for the synthesis of analogs of the aporphine alkaloid nantenine. Our study shows that the aporphine core may be rapidly accessed from benzyl-tetrahydroisoquinoline substrates with this method. This is the first report of a microwave-assisted direct biaryl coupling reaction in the synthesis of aporphine molecules. 相似文献
2.
A copper-mediated annulative direct coupling of o-alkynylphenols with 1,3,4-oxadiazoles proceeds smoothly even under ambient conditions to afford the corresponding biheteroaryls. The reaction system represents a new avenue for the construction of biheteroaryl molecules of interest in their biological and physical properties. 相似文献
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An efficient synthesis of the angiotensin II inhibitor valsartan (Diovan) is presented. Two routes were evaluated, both making use of an advanced version of our decarboxylative coupling for the construction of the biaryl moiety. Thus, in the presence of a catalyst system consisting of copper(II) oxide, 1,10-phenanthroline, and palladium(II) bromide, 2-cyanocarboxylic acid was coupled with 1-bromo(4-dimethoxymethyl)benzene in 80% yield and with 4-bromotoluene in 71% yield. The valsartan synthesis using 1-bromo(4-dimethoxymethyl)benzene was completed in four steps overall with a total yield of 39%, via a novel route that presents substantial economical and ecological advantages over the literature process, as it is more concise and stoichiometric amounts of expensive organometallic reagents are avoided. 相似文献
6.
Tomoki Yoshizumi 《Tetrahedron letters》2008,49(10):1598-1600
The direct arylation of 1,3-benzoazole compounds with aryl iodides is effectively promoted by CuI with use of PPh3 and Na2CO3 or K3PO4 as ligand and base, respectively, in DMF or DMSO to produce the corresponding 2-arylated products with good yields. 相似文献
7.
Ramesh A. Joshi 《Tetrahedron letters》2004,45(1):195-197
Selective N-arylation of aminopurines and aminopyrimidines 1-3 with arylboronic acids 4-6 was explored using copper(II) acetate and the corresponding N-arylated purine and pyrimidine derivatives 7-15 were obtained in moderate to good yields. 相似文献
8.
Xianfeng Li Anna Katrin Szardenings Christopher P. Holmes Liang Wang Ashok Bhandari Lihong Shi Marc Navre Larry Jang J. Russell Grove 《Tetrahedron letters》2006,47(1):19-22
A new method for the synthesis of functionalized biaryl α-ketophosphonic acids has been developed. The key step involves the use of sodium bromobenzoyl phosphonates to react with polymer-bound boronic acids via microwave-assisted aqueous Suzuki coupling. This approach provides rapid access to a wide range of diverse biaryl analogues containing an α-ketophosphonic acid moiety. 相似文献
9.
Mediated by copper acetate, an efficient approach to the C-N bond formation via direct aminolysis of dithioacetals 2 and 5 with ammonia, primary or secondary amines are developed under mild conditions. Enaminones 3 and 6 were thus obtained in high to excellent yields with high chemoselectivity. This type of aminolysis reaction presents a new synthetic application of the dithioacetal functionality. [reaction: see text] 相似文献
10.
Treatment of a benzyl substituted meso-ditriflate with boronic acids in the presence of palladium acetate, triphenylphosphine and caesium fluoride results in intermolecular Suzuki coupling followed by vinyl triflate-arene cyclisation to provide, in high yields, single regioisomers of tricyclic-carbocycles. 相似文献
11.
Copper-mediated, palladium-catalyzed coupling of thiol esters with aliphatic organoboron reagents 总被引:1,自引:0,他引:1
Thiol esters and B-alkyl-9-BBN derivatives couple in the presence of a copper(I) carboxylate mediator and a palladium catalyst. In contrast to copper-mediated, palladium-catalyzed cross-couplings of thioorganics with boronic acids, the current coupling reaction of 9-BBN derivatives is facilitated by the addition of a base such as Cs(2)CO(3). Under optimized conditions, a variety of thiol esters react with different B-alkyl-9-BBN derivatives giving ketones in moderate to excellent yields. 相似文献
12.
Lafrance M Rowley CN Woo TK Fagnou K 《Journal of the American Chemical Society》2006,128(27):8754-8756
Penta-, tetra-, tri-, and difluorobenzenes undergo direct arylation with a wide range of arylhalides in high yield. Inverse reactivity is observed compared to the common electrophilic aromatic substitution pathway since electron-deficient, C-H acidic arenes react preferentially. Computational studies indicate that C-H bond cleavage occurs via a concerted carbon-palladium and carbon-hydrogen bond cleaving event involving a carbonate or a bromide ligand. The reactions are rapid, require only a slight excess of the perfluoroarene reagent, and utilize commercially available, air-stable catalyst precursors. 相似文献
13.
Changhua TangZiyuan Li Yiyun WangJinyi Xu Lingyi KongHequan Yao Xiaoming Wu 《Tetrahedron letters》2011,52(26):3275-3278
The first total synthesis of a sesquiterpenoid, tenuifolin, was achieved in seven linear steps. Phenyliodine(III) bis(trifluoacetate) (PIFA) mediated oxidative biaryl coupling was employed as a key step to construct the central seven-membered ring with a double bond. The double bond formation was also exploited. 相似文献
14.
Pileio G 《The Journal of chemical physics》2011,134(21):214505
The intermolecular contribution to the relaxation of singlet states has been derived on the basis of a translational-rotational diffusion model that describes molecules as impenetrable spheres which translate and rotate in an isotropic low-viscosity medium. The equations for the relaxation rate constants obtained are discussed and the dependence on physical parameters is exploited. Theoretical predictions are compared with experiments when the intermolecular relaxation is due to both protons and deuterons present in the sample. An agreement between experiments and theory of ±4% was obtained when the physical parameters are estimated from first-principles calculation. 相似文献
15.
The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies and couplings between the chlorophyll molecules, and due to the fact that different fluctuations will partially be caused by the same environmental factors, correlations between the various fluctuations will occur. We argue that fluctuations of the couplings should, in general, not be neglected, as these have a considerable impact on population transfer rates, decoherence rates, and the efficiency of photosynthetic complexes. Furthermore, while correlations between transition energy fluctuations have been studied, we provide the first quantitative study of the effect of correlations between coupling fluctuations and transition energy fluctuations, and of correlations between the various coupling fluctuations. It is shown that these additional correlations typically lead to changes in interchromophore transfer rates and population oscillations and can lead to a limited enhancement of the light harvesting efficiency. 相似文献
16.
A direct diastereoselective titanium-mediated intermolecular coupling of internal alkynes with dialkyl carbonates under Kulinkovich-type reaction conditions is presented. The influence of the structures of the coupling partners on the yields and regioselectivities of this transformation is described. 相似文献
17.
[reaction: see text]. Chiral 1,5-diaza-cis-decalins have been examined as ligands in the enantioselective oxidative biaryl coupling of substituted 2-naphthol derivatives. Under the optimal conditions employing a 1,5-diaza-cis-decalin copper(I) iodide complex with oxygen as the oxidant, rapid and highly selective couplings could be achieved (90-93% ee, 85% yield). 相似文献
18.
《Tetrahedron letters》2014,55(50):6899-6902
A metal-free intramolecular biaryl coupling mediated by DDQ and BF3·OEt2 was developed. The reaction proceeds smoothly at room temperature to give seven- and eight-membered heterocyclic biaryl compounds in up to 95% yields. Only 1 equiv of DDQ sufficed for the reaction, obviating the use of a large excess of oxidants and undesired chlorination pathway in metal-mediated process. 相似文献
19.
Significant progress has been made in the direct arylation of simple arenes. A number of catalyst systems have been developed which enable the intramolecular direct arylation of aryl chlorides, bromides and iodides in high yield as well as conditions capable of achieving intermolecular direct arylation with simple arenes. This account describes recent progress by our group and others in the development of these reactions. 相似文献