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1.
The on‐surface coupling reactions of terminal alkynes catalyzed by exogenous cupric ions on chemically inert highly oriented pyrolytic graphite (HOPG) surface have been investigated by scanning tunnelling microscopy. In the presence of exogenous cupric ions, diyne‐linked nanostructures generated via homocoupling of terminal alkynes are the exclusive products, whereas no coupling reaction occurs for the terminal alkynes on the surface in the absence of the cupric ions, suggesting that exogenous cupric ions are efficient to catalyze the highly chemoselective on‐surface reaction of terminal alkynes. The HOPG surface displays a template effect to the growth and alignment of the products on the surface. As a result, 2D arrays of diyne‐linked zigzag polymers and 2D diyne‐linked porous polymers are fabricated from ditopic monomer 3,6‐diethynylcarbazole and tritopic monomer 1,3,5‐tris‐(4‐ethynylphenyl) benzene, respectively. This synthetic strategy combining the high selectivity of cupric ion catalyst as well as the template effect of on‐surface synthesis approach could be a general strategy to fabricate diyne‐linked nanostructures and nanomaterials on solid surfaces. 相似文献
2.
《Tetrahedron letters》2004,45(47):8717-8720
The first total synthesis of 7(S),16(R),17(S)-Resolvin D2, a lipid mediator derived from docosahexaenoic acid, has been achieved. The key features of our synthetic strategy encompass a Co-salen hydrolytic kinetic resolution of a terminal epoxide combined with a chiral pool strategy. 相似文献
3.
Manojit Pal 《Tetrahedron letters》2003,44(45):8221-8225
An efficient synthesis of 2-alkyl/aryl substituted benzo[b]furans/nitrobenzo[b]furans in water has been accomplished via Pd/C catalyzed reaction of o-iodophenols with terminal alkynes in the presence of PPh3, CuI and prolinol. This method can tolerate a variety of functional groups present in the alkynes as well as base labile nitro group in the o-iodophenols. The protocol does not require the use of a phase transfer catalyst or water-soluble phosphine ligands and is free from the use of any organic co-solvent. 相似文献
4.
Sahaj GuptaSudhir K. Sharma Anil K. MandadapuHarsh M. Gauniyal Bijoy Kundu 《Tetrahedron letters》2011,52(33):4288-4291
A simple, highly efficient three-component reaction involving acid chlorides, terminal alkynes, and ethyl 2-amino-1H-indole-3-carboxylates, for the synthesis of highly diversified pyrimido[1,2-a]indoles has been described. The salient feature of the reaction involves sequential Sonogashira and [3+3] cyclocondensation reactions. 相似文献
5.
A general and practical synthesis of 2-substituted 6-oxopyrrolo[3,2,1-ij]quinolines has been achieved following a single-step Pd/C-mediated coupling-cyclization strategy. The methodology involves the reaction of 8-iodo-4-oxo-1,4-dihydro quinoline-3-carboxylic acid ethyl ester with a variety of terminal alkynes in the presence of 10% Pd/C-PPh3-CuI as a catalyst system in EtOH. The reaction mechanism and utility of the methodology have been discussed. 相似文献
6.
Yun-Hua Wang 《Tetrahedron》2010,66(35):7136-6130
A simply performed procedure for the [Rh(cod)Cl]2/cationic 2,2′-bipyridyl system-catalyzed [2+2+2] cycloaddition of α,ω-diynes with terminal and internal alkynes was achieved in water under air at 60 °C. The reaction proceeded smoothly with 1 equiv α,ω-diynes and 3 equiv alkynes in the presence of 20 mol % KOH for 1 h or 9 h, resulting in the formation of tri- and tetra-substituted benzene derivatives in moderate to high yields. After separation of the organic products by extraction, the residual aqueous solution could be reused for further reactions until complete degradation of its catalytic activity. 相似文献
7.
Manjoorahmed Asamdi Mohammedumar M. Shaikh Prakashsingh M. Chauhan Kishor H. Chikhalia 《Tetrahedron》2018,74(27):3719-3727
An efficient and novel method using palladium catalyst for the synthesis of benzo[d][1,2]diazepines by [5 + 2] annulation of N-arylhydrazones with alkynes has been developed. This methodology undergoes through eight membered palladacycle serving as a backbone for the formation of CC/CN bond to provide benzodiazepine derivatives in moderate to good yield. 相似文献
8.
New functionalized quinuclidines were prepared via palladium-catalyzed addition reactions of terminal alkynes (donors) to internal alkynes (acceptors). The enantiopure terminal alkynes were derivatives of quincoridine and quincorine, two semi-natural Cinchona alkaloids. The processes exhibited high chemoselectivity and excellent diastereoselectivity, the E-enynes being obtained as single products in almost all cases. The synthesis of new tetra and pentasubstituted benzene derivatives in good yields by [2+2+2] benzannulation of the diynes, obtained by the palladium-catalyzed homodimerization of 10,11-didehydro quincoridine and 10,11-didehydro quincorine, with terminal alkynes and in fair yield by [4+2] benzannulation of an enyne derivative of 10,11-didehydro quincoridine with 2,4-hexane-diyne are reported. 相似文献
9.
Rémi Lavernhe Dr. Qian Wang Prof. Dr. Jieping Zhu 《Angewandte Chemie (International ed. in English)》2023,62(22):e202303537
Transition-metal-catalyzed [4+2] heteroannulation of α,β-unsaturated oximes and their derivatives with alkynes has been developed into a powerful strategy for the synthesis of pyridines. It nevertheless lacks regioselectivity when unsymmetrically substituted alkynes are used. We report herein the unprecedented synthesis of polysubstituted pyridines by a formal [5+1] heteroannulation of two readily accessible building blocks. A copper-catalyzed aza-Sonogashira cross-coupling between β,γ-unsaturated oxime esters and terminal alkynes affords ynimines, which, without isolation, undergo an acid-catalyzed domino reaction involving ketenimine formation, 6π-electrocyclization and aromatization to afford pyridines. Terminal alkynes served as a one-carbon donor to the pyridine core in this transformation. Di- through pentasubstituted pyridines are accessible with complete regioselectivity and excellent functional-group compatibility. The first total synthesis of anibamine B, an indolizinium alkaloid with potent antiplasmodial activity, was accomplished featuring this reaction as a key step. 相似文献
10.
The synthesis of 1,6-dihydropyrrolo[2,3-g]indazole derivatives is described. The indolic ring system is constructed via a Larock palladium-catalyzed annulation using terminal and internal alkynes. Additionally, when using internal alkynes for this reaction, we found that a directing effect on regioselectivity was mediated by the ester group of alkyl 3-substituted propiolate derivatives. 相似文献
11.
Zhenfa Zhang 《Tetrahedron letters》2011,52(21):2667-2669
Expeditious syntheses of cis-1-methyl-2,3,3a,4,5,9b-hexahydro-1H-pyrrolo-[3,2h]isoquinoline/[2,3-f]quinoline have been developed. The syntheses started with commercially available materials and afforded excellent overall yields in straightforward steps. Intramolecular azomethine ylide-alkene [3+2] cycloaddition is the key step in the construction of these pyrroloisoquinoline and pyrroloquinoline scaffolds. This route is much more atom-economic than those reported in the literature and is appropriate for scale-up synthesis. 相似文献
12.
Generally, synthesis of hydantoin derivatives involve use of carbonyl compounds which in turn require multistep synthesis. Here, we report a new approach to assemble spirohydantoins via [2+2+2] cyclotrimerization reaction using commercially available, inexpensive hydantoin as a starting material. 相似文献
13.
Sirisilla Raju Venkateswara Rao Batchu R. Vasu Dev P. Rajender Kumar Manojit Pal 《Tetrahedron letters》2006,47(1):83-88
We describe here, the first palladium-mediated tandem C-C bond forming reaction between 3-iodothiophene-2-carboxylic acid and terminal alkynes to afford the unexpected 5-substituted 4-alkynylthieno[2,3-c]pyran-7-ones in good yields. 相似文献
14.
The RhCl3·3H2O/i-Pr2NEt-catalyzed [2+2+2] cyclotrimerization of alkynes has been achieved. The reaction can be widely used for various alkynes and provides tri- or hexa-substituted benzenes regioselectively in high yields. The [2+2+2] cycloaddition of diynes and alkynes is also developed, and it affords benzene derivatives in moderate to high yields. 相似文献
15.
Alexander S. Tikhomirov Andrey E. Shchekotikhin Yuri N. Luzikov Alexander M. Korolev Maria N. Preobrazhenskaya 《Tetrahedron》2014
A new facile route to the synthesis of 4,11-dimethoxyanthra[2,3-b]furan-5,10-dione and its novel 2-substituted derivatives was proposed. The developed scheme was based on a Pd-catalyzed cross-coupling/heterocyclization domino reaction of 3-bromo-2-hydroxy-4,11-dimethoxyanthraquinone with terminal alkynes. 相似文献
16.
Issa Yavari Salome AhmadianMajid Ghazanfarpur-Darjani Yazdan Solgi 《Tetrahedron letters》2011,52(6):668-670
A copper-catalyzed synthesis of N-sulfonylamidines via three-component coupling of sulfonyl azides, terminal alkynes, and trialkylamines is reported. 相似文献
17.
18.
Yi Wang 《Journal of fluorine chemistry》2007,128(9):1052-1057
A site-specific synthesis of 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes is described. The reactions of heterocyclic aromatic aldehydes with a Wittig reagent, followed by Sonogashira reaction with terminal alkynes, and subsequent base-catalyzed cyclization site-specifically provide 4-substituted-6-fluoro(carboalkoxyl)benzo[b]furans and benzo[b]thiophenes in good yields. 相似文献
19.
Mira Beshai 《Tetrahedron letters》2008,49(48):6794-6796
Terminal alkynes were prepared in near quantitative yields via dehydrohalogenation of (Z)-1-iodo-1-alkenes with tetrabutylammonium fluoride (TBAF) under mild conditions. The methodology was expanded to include a one-pot, direct synthesis of terminal alkynes from aldehydes without the necessity of isolating and purifying the intermediate iodoalkene. 相似文献
20.
New 2-substituted pyrazolo[5,1-b][1,3]oxazoles are synthesized through the Sonogashira coupling reaction of 2-iodomethyl-6-methylpyrazolo[5,1-b][1,3]oxazole with terminal alkynes in the presence of a palladium catalyst. This process is carried out in the absence of any copper salt, and provides an eco-friendly and efficient method for the synthesis of the products in water in good-to-high yields. Some of the compounds synthesized were screened for their in vitro anti-oxidant activity using the DPPH (2,2-diphenyl-2-picrylhydrazyl) assays. 相似文献