Search results for "Iminium"
showing 10 items of 75 documents
CCDC 1414523: Experimental Crystal Structure Determination
2016
Related Article: Vanessa Soto-Cerrato, Pilar Manuel-Manresa, Elsa Hernando, Silvia Calabuig-Fariñas, Alicia Martínez-Romero, Víctor Fernández-Dueñas, Kristoffer Sahlholm, Thomas Knöpfel, María García-Valverde, Ananda M. Rodilla, Eloisa Jantus-Lewintre, Rosa Farràs, Francisco Ciruela, Ricardo Pérez-Tomás, and Roberto Quesada|2015|J.Am.Chem.Soc.|137|15892|doi:10.1021/jacs.5b09970
Iminium Catalysis (n → π*)
2016
On the Road to MM′X Polymers: Redox Properties of Heterometallic Ni···Pt Paddlewheel Complexes
2014
On the quest of heterometallic mixed-valence MM'X chains, we have prepared two stable discrete bimetallic compounds: the reduced (PPN)[ClNi(μ-OSCPh)4Pt] (PPN = bis(triphenylphosphine)iminium; OSCPh = benzothiocarboxylato) and the oxidized [(H2O)Ni(μ-OSCPh)4PtCl] species. The role of the aqua and chlorido axial ligands is crucial to facilitate oxidation of the {Ni(μ-OSCPh)4Pt} core. Experimental and theoretical analyses indicate that a NiPt-Cl/Cl-NiPt isomerization process occurs in the oxidized species. The electronic structure of the reduced system shows two unpaired electrons, one located in a d(x(2)-y(2)) orbital of the Ni(II) ion and a second in the antibonding d(z(2)-dz(2)) combination…
Investigation of Isoindolo[2,1-a] quinoxaline-6-imines as Topoisomerase I Inhibitors with Molecular Modeling Methods
2017
Background: Isoindolo[2,1-alpha] quinoxalines constitute an important class of compounds which demonstrated potent antiproliferative activity against different human tumor cell lines and topoisomerase I inhibitors. In particular, their water soluble imine or iminium salts recently synthesized showed potent growth inhibitory effect on NCI-60 tumor cell line panel and biological studies performed on the most active compounds demonstrated that they cause DNA damage via topoisomerase I poisoning. Objective: Herein, we investigate with molecular modeling methods, the common features responsible for topoisomerase I inhibition of the water-soluble isoindolo[2,1-alpha] quinoxalin-6-imines, by compa…
CCDC 1402129: Experimental Crystal Structure Determination
2016
Related Article: Carla Queirós, Andreia Leite, Maria G. M. Couto, mLuís Cunha-Silva, Giampaolo Barone, Baltazar de Castro, Maria Rangel, André M. N. Silva, Ana M. G. Silva|2015|Chem.-Eur.J.|21|15692|doi:10.1002/chem.201502093
Aminosäureester als chirale Hilfsgruppen in Lewis-Säure-katalysierten Diels-Alder-Reaktionen
1990
Amino Acid Esters as Chiral Auxiliaries in Lewis Acid Catalyzed Diels-Alder Reactions Cyclopentadiene, cyclohexadiene and alkyl-substituted butadienes react with N-acryloyl-, N-crotonoyl- and N-(4-nitro-cinnamoyl)-(S)-proline benzyl and allyl ester in the presence of Lewis acids to give the cycloadducts in high yields and with stereoselectivities of up to 97:3 for the endo isomers. The sense of the asymmetric induction in these reactions can be directed by the use of differently coordinating catalysts (e.g. TiCl4: (2R):(2S) = 96:4; EtAlCl2: (2R):(2S) = 10:90 at 0°C). In the TiCl4-catalyzed reactions with the fumaric acid derivatives the ratio of the diastereomers reaches values of up to 112…
2014
Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…
ChemInform Abstract: Radical Addition to Iminium Ions and Cationic Heterocycles
2015
Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta react…
1,3-Benzyl Migration in Iminium Ions: Evidence for a Fast Free-Radical Chain Reaction
2011
The “exocyclic” 1,3-benzyl shift observed in iminium salts derived from 1-benzyl-1,2,3,4-tetrahydroisoquinolines is related to the “endocyclic” Knabe rearrangement. A crossover experiment, isotopic labelling, the study of initiators and inhibitors as well as DFT calculations of gas-phase model structures provide evidence for a free-radical pathway under kinetic entropy control that is not affected by “slow” radical traps.
Unveiling the Intramolecular Ionic Diels–Alder Reactions within Molecular Electron Density Theory
2021
The intramolecular ionic Diels–Alder (IIDA) reactions of two dieniminiums were studied within the Molecular Electron Density Theory (MEDT) at the ωB97XD/6-311G(d,p) computational level. Topological analysis of the electron localization function (ELF) of dieniminiums showed that their electronic structures can been seen as the sum of those of butadiene and ethaniminium. The superelectrophilic character of dieniminiums accounts for the high intramolecular global electron density transfer taking place from the diene framework to the iminium one at the transition state structures (TSs) of these IIDA reactions, which are classified as the forward electro density flux. The activation enthalpy ass…