0000000001306206
AUTHOR
Sandra Kaabel
CaCl2, Bisoxazoline, and Malonate: A Protocol for an Asymmetric Michael Reaction
A mild protocol for the asymmetric Michael addition of dimethyl malonate to various α,β-unsaturated carbonyl compounds was developed. The salient feature of this methodology is that a cheap and environmentally friendly Lewis acid, CaCl2, was used as a catalyst. An aminoindanol- and pyridine-derived ligand provided in the presence of CaCl2 Michael adducts in moderate to high enantioselectivities. The scope of the reaction was demonstrated.
Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
A novel eight-membered macrocycle of the hemicucurbit[n]uril family, chiral (all-R)-cyclohexanohemicucurbit[8]uril (cycHC[8]) binds anions in a purely protic solvent with remarkable selectivity. The cycHC[8] portals open and close to fully encapsulate anions in a 1 : 1 ratio, resembling a molecular Pac-Man™. Comprehensive gas, solution and solid phase studies prove that the binding is governed by the size, shape and charge distribution of the bound anion. Gas phase studies show an order of SbF6− ≈ PF6− > ReO4− > ClO4− > SCN− > BF4− > HSO4− > CF3SO3− for anion complexation strength. An extensive crystallographic study reveals the preferred orientations of the anions within the octahedral cav…
Formation and trapping of the thermodynamically unfavoured inverted-hemicucurbit[6]uril
Amplification of a thermodynamically unfavoured macrocyclic product through the directed shift of the equilibrium between dynamic covalent chemistry library members is difficult to achieve. We show for the first time that during condensation of formaldehyde and cis-N,N'-cyclohexa-1,2-diylurea formation of inverted-cis-cyclohexanohemicucurbit[6]uril (i-cis-cycHC[6]) can be induced at the expense of thermodynamically favoured cis-cyclohexanohemicucurbit[6]uril (cis-cycHC[6]). The formation of i-cis-cycHC[6] is enhanced in low concentration of the templating chloride anion and suppressed in excess of this template. We found that reaction selectivity is governed by the solution-based template-a…
Synthesis and Characterisation of Chiral Triazole-Based Halogen-Bond Donors: Halogen Bonds in the Solid State and in Solution
A general platform for the synthesis of various chiral halogen-bond (XB) donors based on the triazole core and the characterisation of factors that influence the strength of the halogen bond in the solid state and in solution are reported. The characterisation of XB donors in the solid state by X-ray crystallography and in solution by 1H NMR titration can be used to aid the design of new XB donors. We describe the first example of a XB between iodotriazoles and thioureas in solution. In addition, the enantiodiscrimination of acceptors in solution through halogen-bond participation is described.
Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
A novel eight-membered macrocycle of the hemicucurbit[n]uril family, chiral (all-R)-cyclohexanohemicucurbit[8]uril (cycHC[8]) binds anions in a purely protic solvent with remarkable selectivity. The cycHC[8] portals open and close to fully encapsulate anions in a 1 : 1 ratio, resembling a molecular Pac-Man™. Comprehensive gas, solution and solid phase studies prove that the binding is governed by the size, shape and charge distribution of the bound anion. Gas phase studies show an order of SbF6− ≈ PF6− > ReO4− > ClO4− > SCN− > BF4− > HSO4− > CF3SO3− for anion complexation strength. An extensive crystallographic study reveals the preferred orientations of the anions within the octahedral cav…
Template-controlled synthesis of chiral cyclohexylhemicucurbit[8]uril
Enantiomerically pure cyclohexylhemicucurbit[8]uril (cycHC[8]), possessing a barrel-shaped cavity, has been prepared in high yield on a gram scale from either (R,R,N,N')-cyclohex-1,2-diylurea and formaldehyde or cycHC[6]. In either case, a dynamic covalent library is first generated from which the desired cycHC can be amplified using a suitable anion template.
Asymmetric Organocatalytic Wittig [2,3]-Rearrangement of Oxindoles
A highly enantioselective organocatalytic [2,3]-rearrangement of oxindole derivatives is presented. The reaction was catalyzed by squaramide, and this provides access to 3-hydroxy 3-substituted oxindoles in high enantiomeric purities.
Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution† †Electronic supplementary information (ESI) available: MS, NMR, dynamic NMR and computational details and a DFT-based video of complexation. CCDC 1514736–1514741, 1521388. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c6sc05058a Click here for additional data file. Click here for additional data file. Click here for additional data file.
Chiral (all-R)-cyclohexanohemicucurbit[8]uril binds anions in a 1 : 1 ratio in pure methanol like a molecular Pac-Man™ with remarkable selectivity based on the size, shape and charge distribution of the anion.
Asymmetric Organocatalytic Michael Addition–Cyclization Cascade of Cyclopentane-1,2-dione with Substituted α,β-Unsaturated Aldehydes
An asymmetric organocatalytic Michael addition–cyclization cascade reaction has been developed using cyclopentane-1,2-dione as a Michael donor and α,β-unsaturated aldehydes as Michael acceptors. Bicyclic hemiacetals were obtained in excellent yields and enantioselectivities. On the basis of the results, a one-pot reaction has been developed to obtain chiral 3-substituted cyclopentane-1,2-diones and substituted dihydropyrans in good yields and excellent enantioselectivity.
CCDC 1569570: Experimental Crystal Structure Determination
Related Article: Elena Prigorchenko, Sandra Kaabel, Triin Narva, Anastassia Baškir, Maria Fomitšenko, Jasper Adamson, Ivar Järving, Kari Rissanen, Toomas Tamm, Riina Aav|2019|Chem.Commun.|55|9307|doi:10.1039/C9CC04990H
CCDC 1514740: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1056977: Experimental Crystal Structure Determination
Related Article: Kristin Lippur , Sandra Kaabel , Ivar Järving , Kari Rissanen , and Tõnis Kanger|2015|J.Org.Chem.|80|6336|doi:10.1021/acs.joc.5b00769
CCDC 1514737: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1522088: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522089: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522081: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1447017: Experimental Crystal Structure Determination
Related Article: Maksim Ošeka, Mariliis Kimm, Sandra Kaabel, Ivar Järving, Kari Rissanen, and Tõnis Kanger|2016|Org.Lett.|18|1358|doi:10.1021/acs.orglett.6b00291
CCDC 1522087: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522085: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1447018: Experimental Crystal Structure Determination
Related Article: Maksim Ošeka, Mariliis Kimm, Sandra Kaabel, Ivar Järving, Kari Rissanen, and Tõnis Kanger|2016|Org.Lett.|18|1358|doi:10.1021/acs.orglett.6b00291
CCDC 1514738: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1514739: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1522082: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
Chiral hemicucurbit[8]uril as an anion receptor: selectivity to size, shape and charge distribution
Chiral (all-R)-cyclohexanohemicucurbit[8]uril binds anions in a 1 : 1 ratio in pure methanol like a molecular Pac-Man™ with remarkable selectivity based on the size, shape and charge distribution of the anion.
CCDC 1522086: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522080: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522079: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522084: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1522083: Experimental Crystal Structure Determination
Related Article: Mikk Kaasik, Sandra Kaabel, Kadri Kriis, Ivar Järving, Riina Aav, Kari Rissanen, Tönis Kanger|2017|Chem.-Eur.J.|23|7337|doi:10.1002/chem.201700618
CCDC 1521388: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1514736: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A
CCDC 1514741: Experimental Crystal Structure Determination
Related Article: Sandra Kaabel, Jasper Adamson, Filip Topić, Anniina Kiesilä, Elina Kalenius, Mario Öeren, Mart Reimund, Elena Prigorchenko, Aivar Lõokene, Hans J. Reich, Kari Rissanen, Riina Aav|2017|Chemical Science|8|2184|doi:10.1039/C6SC05058A