195044-14-5Relevant articles and documents
Steric Protection of Rhodium-Nitridyl Radical Species
Rebreyend, Christophe,Mouarrawis, Valentinos,Siegler, Maxime A.,van der Vlugt, Jarl Ivar,de Bruin, Bas
, p. 4249 - 4255 (2019)
In an attempt to synthesize a mononuclear rhodium nitridyl complex with a reduced tendency to undergo nitridyl radical N–N coupling, we synthesized a bulky analog of Milstein's bipyridine-based PNNH ligand, bearing a tert-butyl group at the 6′ position of the bipyridine moiety. A three-step synthetic route toward this new bulky tBu3PNNH ligand was developed, involving a selective nucleophilic substitution step, followed by a Stille coupling and a final hydrophosphination step to afford the desired 6-(tert-butyl)-6′-[(di-tert-butylphosphino)methyl]-2,2′-bipyridine (tBu3PNNH) ligand. This newly developed tBu3PNNH ligand was incorporated in the synthesis of the sterically protected azide complex [Rh(N3)(tBu3PNNH)]. We explored N2 elimination form this species using photolysis and thermolysis, hoping to synthesize a mononuclear rhodium complex with a terminal nitrido moiety. Characterization of the reaction product(s) using NMR, coldspray HR-ESI-MS and EPR spectroscopy shows that the material is paramagnetic, and data obtained by MS spectrometry revealed masses corresponding with both monomeric and dimeric nitrido/nitridyl complexes. NMR only reveals broad uncharacteristic signals and the complex is EPR silent at 8K or above. The combined data point to formation of a paramagnetic [(tBu3PNN)Rh(μ-N)Rh(tBu3PNN)] species. It thus seems that despite its three tBu groups the new ligand is not bulky enough to prevent formation of Rh–N–Rh bridged species. However, the increased steric environment does prevent further reaction with carbon monoxide, which is unable to coordinate to rhodium.
MODULATORS OF CYSTIC FIBROSIS TRANSMEMBRANE CONDUCTANCE REGULATOR
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Paragraph 00391, (2021/02/19)
This disclosure provides modulators of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR), pharmaceutical compositions containing at least one such modulator, methods of treatment of cystic fibrosis using such modulators and pharmaceutical compositions, and processes for making such modulators.
Chiral Memory in Silyl-Pyridinium and Quinolinium Cations
Fernandes, Anthony,Laye, Claire,Pramanik, Suman,Palmeira, Dayvson,Pekel, ?zgen ?mür,Massip, Stéphane,Schmidtmann, Marc,Müller, Thomas,Robert, Frédéric,Landais, Yannick
supporting information, p. 564 - 572 (2020/01/09)
Pyridine- and quinoline-stabilized silyl cations have been prepared, and their structure in condensed phases unambiguously assigned using 1H, 13C, 15N, 29Si, and 1H DOSY NMR as well as X-ray diffraction studies. Solid state structures thus show in both cases a stabilization of the cationic silicon center through an N-Si interaction and formation of a highly strained four-membered ring system. Chiral memory at the silicon atom in these heterocycle-stabilized silyl cations was also established, leading to various levels of selectivity depending on the nature of the heterocycle. Lowest energy conformations of the starting silanes obtained through DFT calculations, along with the isolation and characterization of the Si-centered chiral silyl cation intermediates, finally allowed to propose a plausible hypothesis as to the configurational stability of these silyl cations.