105560-52-9Relevant articles and documents
Adaptive Behavior of Dynamic Orthoester Cryptands
Shyshov, Oleksandr,Brachvogel, René-Chris,Bachmann, Tobias,Srikantharajah, Rubitha,Segets, Doris,Hampel, Frank,Puchta, Ralph,von Delius, Max
, p. 776 - 781 (2017)
The integration of dynamic covalent bonds into macrocycles has been a tremendously successful strategy for investigating noncovalent interactions and identifying effective host–guest pairs. While numerous studies have focused on the dynamic responses of macrocycles and larger cages to various guests, the corresponding constitutionally dynamic chemistry of cryptands remains unexplored. Reported here is that cryptands based on orthoester bridgeheads offer an elegant entry to experiments in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents. In such dynamic mixtures, the alkali metal ions Li+, Na+, K+, Rb+, and Cs+exhibit pronounced preferences for the formation of cryptands of certain sizes and donor numbers, and the selection is rationalized by DFT calculations. Reported is also the first self-assembly of a chiral orthoester cryptate and a preliminary study on the use of stereoisomers as subcomponents.
Syntheses, characterisation and solid-state study of alkali and ammonium BArF salts
Carreras, Lucas,Rovira, Laura,Vaquero, Mónica,Mon, Ignasi,Martin, Eddy,Benet-Buchholz, Jordi,Vidal-Ferran, Anton
, p. 32833 - 32841 (2017)
A new synthetic protocol for synthesising a number of BArF derivatives has been developed. Single crystal X-ray analysis of an array of alkali metal and ammonium salts has allowed the determination of the coordination sphere and/or the map of short contacts of the positively charged atoms. The increasing number of coordination bonds and/or short contacts between the alkali metal cation and the surrounding atoms has been rationalised in terms of the size of the alkali metal centre. It has also been demonstrated that an increase in the number of coordination bonds and/or short contacts translates into longer M-F distances. In the case of the ammonium BArF salts, the N-B distances are shorter than the M-B distances in the alkali metal BArF salts, indicating stronger interactions between the cationic nitrogen and the anionic boron than those between the boron and the alkali metal centres. Finally, a study of the structures of alkali metal hydrated and THF-solvated BArF salts showed that the interactions between the metal centre and the surrounding atoms depend not only on the size of the alkali metal centre but also on the occupancy of the first coordination sphere.
Supramolecularly Regulated Ligands for Asymmetric Hydroformylations and Hydrogenations
Vidal-Ferran, Anton,Mon, Ignasi,Bauzá, Antonio,Frontera, Antonio,Rovira, Laura
supporting information, p. 11417 - 11426 (2015/08/03)
Herein we report the use of polyether binders as regulation agents (RAs) to enhance the enantioselectivity of rhodium-catalyzed transformations. For reactions of diverse substrates mediated by rhodium complexes of the α,ω-bisphosphite-polyether ligands 1-5,a-d, the enantiomeric excess (ee) of hydroformylations was increased by up to 82 (substrate: vinyl benzoate, 96ee), and the ee value of hydrogenations was increased by up to 5 (substrate: N-(1-(naphthalene-1-yl)vinyl)acetamide, 78ee). The ligand design enabled the regulation of enantioselectivity by generation of an array of catalysts that simultaneously preserve the advantages of a privileged structure in asymmetric catalysis and offer geometrically close catalytic sites. The highest enantioselectivities in the hydroformylation of vinyl acetate with ligand 4b were achieved by using the Rb[B(3,5-(CF3)2C6H3)4] (RbBArF) as the RA. The enantioselective hydrogenation of the substrates 10 required the rhodium catalysts derived from bisphosphites 3a or 4a, either alone or in combination with different RAs (sodium, cesium, or (R,R)-bis(1-phenylethyl)ammonium salts). This design approach was supported by results from computational studies.
