0000000001300170
AUTHOR
Gerhard Raabe
From attraction to repulsion : anion–π interactions between bromide and fluorinated phenyl groups
Anion–π interactions in crystals of fluorobenzyl ammonium salts depend on the degree of fluorination at the aromatics.
Anion Receptors Based on a Quinoline Backbone
2-Amido-8-urea substituted quinoline derivatives are potent receptors for the binding of halide or benzoate anions in chloroform. The selectivity and affinity of the receptors for fluoride can be tuned by variation of the substituents at the receptor side chains. Computational considerations show that the cleft of the receptors provides space for effective binding of F–, but not bigger anions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
CF3: An Electron-Withdrawing Substituent for Aromatic Anion Acceptors? “Side-On” versus “On-Top” Binding of Halides
The ability of multiple CF3 -substituted arenes to act as acceptors for anions is investigated. The results of quantum-chemical calculations show that a high degree of trifluoromethyl substitution at the aromatic ring results in a positive quadrupole moment. However, depending on the polarizability of the anion and on the substitution at the arene, three different modes of interaction, namely Meisenheimer complex, side-on hydrogen bonding, or anion-π interaction, can occur. Experimentally, the side-on as well as a η(2) -type π-complex are observed in the crystal, whereas in solution only side-on binding is found.
Asymmetric Synthesis of Spiro Tetrahydrothiophene-indan-1,3-diones via a Squaramide-Catalyzed Sulfa-Michael/Aldol Domino Reaction
Synthesis 48(08), 1131-1138(2016). doi:10.1055/s-0035-1560412
Shedding Light on the Interactions of Hydrocarbon Ester Substituents upon Formation of Dimeric Titanium(IV) Triscatecholates in DMSO Solution
Abstract The dissociation of hierarchically formed dimeric triple lithium bridged triscatecholate titanium(IV) helicates with hydrocarbyl esters as side groups is systematically investigated in DMSO. Primary alkyl, alkenyl, alkynyl as well as benzyl esters are studied in order to minimize steric effects close to the helicate core. The 1H NMR dimerization constants for the monomer–dimer equilibrium show some solvent dependent influence of the side chains on the dimer stability. In the dimer, the ability of the hydrocarbyl ester groups to aggregate minimizes their contacts with the solvent molecules. Due to this, most solvophobic alkyl groups show the highest dimerization tendency followed by…
A Supramolecular Chiral Auxiliary Approach: “Remote Control ”of Stereochemistry at a Hierarchically Assembled Dimeric Helicate
Dimeric hierarchically-assembled titanium(IV) helicates are in solvent-dependent equilibrium with the corresponding monomers. Statistically formed mixtures of such complexes bearing chiral stereocontrolling ligands and achiral diene-substituted ligands show high diastereoselectivity and reasonable enantioselectivity in the Diels-Alder reaction with maleimides if the reaction proceeds with the dimer but not with the monomer. Thus, solvent dependent switching between the monomer and dimer enables on/off switching of the enantioselectivity.
Cooperativity of H-bonding and anion–π interaction in the binding of anions with neutral π-acceptors
A rare anion-π complex between bromide and a neutral receptor is reported and related receptor systems are studied with a series of anions. The interaction is observed in the solid state and in solution, and further evidence for it is obtained by a computational study.
Asymmetric Synthesis of Tetrahydrobenzofurans and Annulated Dihydropyrans via Cooperative One-Pot Organo- and Silver-Catalysis
Synthesis : journal of synthetic organic chemistry 48(19), 3207-3216(2016). doi:10.1055/s-0035-1561468
Asymmetric, Three-Component, One-Pot Synthesis of Spiropyrazolones and 2,5-Chromenediones from Aldol Condensation/NHC-Catalyzed Annulation Reactions
A novel one-pot, three-component diastereo- and enantioselective synthesis of spiropyrazolones has been developed involving the aldol condensation of an enal to generate α,β-unsaturated pyrazolones, which react with a second equivalent of enal through an N-heterocyclic carbene (NHC)-catalyzed [3+2] annulation. The desired spirocyclopentane pyrazolones are obtained in moderate to good yields and good to excellent stereoselectivities. Alternatively, starting from cyclic 1,3-diketones, 2,5-chromenediones are available through [2+4] annulation.
Anion–π Interactions in Salts with Polyhalide Anions: Trapping of I 4 2−
The directionality of interaction of electron-deficient π systems with spherical anions (e.g,. halides) can be controlled by secondary effects like NH or CH hydrogen bonding. In this study a series of pentafluorophenyl-substituted salts with polyhalide anions is investigated. The compounds are obtained by aerobic oxidation of the corresponding halide upon crystallization. Solid-state structures reveal that in bromide 2, directing NH-anion interactions position the bromide ion in an η(1)-type fashion over but not in the center of the aromatic ring. The same directing forces are effective in corresponding tribromide salt 3. In the crystal, the bromide ion is paneled by four electron-deficient…
CCDC 1950786: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1040204: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1919187: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1917460: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1040206: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1040201: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1474771: Experimental Crystal Structure Determination
Related Article: Uğur Kaya, Pankaj Chauhan, Kristina Deckers, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Synthesis|48|3207|doi:10.1055/s-0035-1561468
CCDC 1474975: Experimental Crystal Structure Determination
Related Article: Uğur Kaya, Pankaj Chauhan, Kristina Deckers, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Synthesis|48|3207|doi:10.1055/s-0035-1561468
CCDC 1040203: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1438663: Experimental Crystal Structure Determination
Related Article: David Van Craen, Markus Albrecht, Gerhard Raabe, Fangfang Pan, Kari Rissanen|2016|Chem.-Eur.J.|22|3255|doi:10.1002/chem.201600158
CCDC 1040202: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1442230: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Pankaj Chauhan, Daniel Hack,Arne R. Philipps, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Chem.-Eur.J.|22|5123|doi:10.1002/chem.201600515
CCDC 1040207: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1919188: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1040205: Experimental Crystal Structure Determination
Related Article: Markus Albrecht, Yi Hai, Okan Köksal, Gerhard Raabe, Fangfang Pan, Arto Valkonen and Kari Rissanen|2016|Chem.-Eur.J.|22|6596|doi:10.1002/chem.201600249
CCDC 1446165: Experimental Crystal Structure Determination
Related Article: Lei Wang, Sun Li, Pankaj Chauhan, Daniel Hack,Arne R. Philipps, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Chem.-Eur.J.|22|5123|doi:10.1002/chem.201600515
CCDC 1437740: Experimental Crystal Structure Determination
Related Article: Suruchi Mahajan, Pankaj Chauhan, Marcus Blümel, Rakesh Puttreddy, Kari Rissanen, Gerhard Raabe, Dieter Enders|2016|Synthesis|48|1131|doi:10.1055/s-0035-1560412
CCDC 1919186: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1917415: Experimental Crystal Structure Determination
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639