The Experts below are selected from a list of 1461 Experts worldwide ranked by ideXlab platform
Matthias F Bickelhaupt - One of the best experts on this subject based on the ideXlab platform.
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indenyl effect due to metal slippage computational exploration of rhodium catalyzed acetylene 2 2 2 Cyclotrimerization
ChemPhysChem, 2014Co-Authors: Laura Orian, Marcel Swart, Matthias F BickelhauptAbstract:The mechanism of CpRh (Cp=cyclopentadienyl) and IndRh (Ind=indenyl)-catalyzed acetylene [2+2+2] Cyclotrimerization has been revisited aiming at finding an explanation for the better performance of the latter catalyst found experimentally. The hypothesis that an ancillary ligand of the precatalyst remains bonded to the metal center throughout the whole catalytic cycle, based on the experimental evidence that the nature of this ligand can exert some control in coCyclotrimerization of different alkynes, is considered. Strong hapticity variations occur in both the CpRh- and IndRh-catalyzed processes. As the Ind ligand undergoes a more facile slippage than Cp, the energy profile is far smoother in the IndRh-catalyzed Cyclotrimerization. This difference in the energetics of the process translates into an enhanced activity of the IndRh catalyst, in nice agreement with experiment.
Martin Kotora - One of the best experts on this subject based on the ideXlab platform.
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synthesis of new bipyridine n n dioxides and their application in asymmetric allylation of benzaldehyde and aldol addition to acetophenone
Monatshefte Fur Chemie, 2019Co-Authors: Ivana Cisařova, Eva Bednařova, David Necas, Michal Dusek, Frederic Lamaty, Martin KotoraAbstract:Two methods for the synthesis of new axially chiral bipyridine N,N′-dioxides based on catalytic [2+2+2] Cyclotrimerization of diynes with nitriles were developed. The N,N′-dioxides were used as catalysts in enantioselective allylation of benzaldehyde with allyltrichlorosilane and aldol reaction of trichlorosilyl ketene acetal of methyl acetate with acetophenone.
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a 2 2 2 Cyclotrimerization approach to selectively substituted fluorenes and fluorenols and their conversion to 9 9 spirobifluorenes
Chemistry: A European Journal, 2015Co-Authors: Reinhard P Kaiser, Filip Hessler, Jiři Mosinger, Ivana Cisařova, Martin KotoraAbstract:Synthesis of selectively substituted fluorenes and fluorenols was achieved by using catalytic [2+2+2]Cyclotrimerization. Various starting diynes were reacted with different alkynes in the presence of a catalytic amount of Wilkinson's catalyst (RhCl(PPh3)3) providing the compounds possessing the fluorene scaffold in good isolated yields. A set of four regioselectively substituted fluorenols was converted to the corresponding 9,9'-spirobifluorenes and their spectral characteristics were measured.
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co and homoCyclotrimerization reactions of protected 1 alkynyl 2 deoxyribofuranose synthesis of c nucleosides c di and c trisaccharide analogues
ChemInform, 2008Co-Authors: Petr Novak, Martin Kotora, Sylva Cihalova, Miroslav Otmar, Michal HocekAbstract:Abstract Cyclotrimerization of β- or α-ethynyl-3,5-di- O -toluoyl-2-deoxy- d -ribofuranose with α,ω-diynes proceeded smoothly under Rh-catalysis to afford the corresponding β- or α-benzene C -nucleoside derivatives. Analogous co-Cyclotrimerization of α- or β-propynyl- and -phenylethynyl-3,5-di- O -toluoyl-2-deoxy- d -ribofuranose with α,ω-diynes gave the corresponding arene derivatives only under microwave irradiation in the presence of a Rh-catalyst in moderate yields. Attempted homoCyclotrimerization of β- or α-ethynyl-3,5-di- O -toluoyl-2-deoxy- d -ribofuranose under Rh-catalysis led only to enynes while the use of Ru-catalyst gave the desired 1,2,4- and 1,3,5-tri-(2-deoxyribofuranose-1-yl)benzene.
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preparation of highly substituted 6 arylpurine ribonucleosides by ni catalyzed Cyclotrimerization scope of the reaction
Journal of Organic Chemistry, 2006Co-Authors: Pavel Turek, Michal Hocek, Petr Novak, Radek Pohl, Martin KotoraAbstract:Transition metal complex catalyzed coCyclotrimerization of protected alkynylpurine ribonucleosides 1 with various diynes 2 gave rise to a series of 6-arylpurine nucleosides 3 that were further deprotected to free nucleosides 4. Generally, the best yields of Cyclotrimerizations were obtained with a catalytic system Ni(cod)2/2PPh(3). On the other hand, CoBr(PPh(3))3 proved to be a superior catalyst for Cyclotrimerization of 1 with dipropargyl ether 2g. In addition, Ni catalysis is also suitable for direct Cyclotrimerization of unprotected alkynylpurine ribonucleosides 5 to the corresponding 6-arylpurinylribosides 4.
Gaddamedi Sreevani - One of the best experts on this subject based on the ideXlab platform.
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Diversity-oriented synthesis of spirothiazolidinediones and their biological evaluation.
Beilstein journal of organic chemistry, 2019Co-Authors: Sambasivarao Kotha, Gaddamedi Sreevani, Lilya U. Dzhemileva, Milyausha M. Yunusbaeva, Usein M. Dzhemilev, Vladimir A. D’yakonovAbstract:We report a new synthetic approach to assemble spirothiazolidinediones via a [2 + 2 + 2] Cyclotrimerization reaction and the derivatives were further functionalized through DA chemistry and click reaction. Using flow cytometry, it was shown for the first time that the new benzyl alcohol derivatives of thiazolidine-2,4-dione generated here are efficient apoptosis inducers in the HeLa, Hek293, U937, Jurkat, and K562 cell lines.
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synthesis of benzyl halide derivatives of spirohydantoins via 2 2 2 Cyclotrimerization reaction
Tetrahedron Letters, 2018Co-Authors: Sanbasivarao Kotha, Gaddamedi SreevaniAbstract:Abstract 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.
Alexander Deiters - One of the best experts on this subject based on the ideXlab platform.
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phenanthridine synthesis via 2 2 2 Cyclotrimerization reactions
Organic and Biomolecular Chemistry, 2008Co-Authors: Lakshminath Sripada, Jesse A Teske, Alexander DeitersAbstract:A concise synthesis of phenanthridines via a microwave-assisted [2+2+2] Cyclotrimerization reaction has been developed.
Chepuri V. Ramana - One of the best experts on this subject based on the ideXlab platform.
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Alkyne [2 + 2 + 2]-Cyclotrimerization Approach for Synthesis of 6,7-Cyclopropylallocolchicinoids
The Journal of Organic Chemistry, 2016Co-Authors: Atul A. More, Chepuri V. RamanaAbstract:Employing a cobalt-catalyzed [2 + 2 + 2] alkyne Cyclotrimerization as the final step, the short and efficient synthesis of cyclopropylallocolchicinoid and its analogues having functional group variations at C9 and/or C10 and C11 of ring C has been accomplished.
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Alkyne [2 + 2 + 2]-Cyclotrimerization Approach for Synthesis of 6,7‑Cyclopropylallocolchicinoids
2016Co-Authors: Atul A. More, Chepuri V. RamanaAbstract:Employing a cobalt-catalyzed [2 + 2 + 2] alkyne Cyclotrimerization as the final step, the short and efficient synthesis of cyclopropylallocolchicinoid and its analogues having functional group variations at C9 and/or C10 and C11 of ring C has been accomplished
