33674-96-3Relevant articles and documents
Reversible constitutional switching between macrocycles and polymers induced by shape change in a dynamic covalent system
Ulrich, Sebastien,Buhler, Eric,Lehn, Jean-Marie
, p. 271 - 292 (2009)
We report here the development of morphological switches as a new tool that can be used in constitutional dynamic chemistry (CDC) to control the constitution of the whole dynamic system. Molecules that have well-defined but switchable shapes were designed and synthesized. Their restrained conformational states were characterized both in the solid and in solution. The addition of metal ions induces a shape change through coordination; the shape generated was also fully investigated both in the solid and in solution. Such molecules constitute morphological switches, meaning that they can explore various shape states as a result of controlled well-defined shape changes triggered by an effector. These morphological switches were then integrated into covalent dynamic systems through formation of reversible imine bonds. Thermodynamic and kinetic analyses were performed in order to quantify the covalent equilibrium and to investigate the labile character of the covalent reversible link. It was then demonstrated that the molecular shape state of the morphological switches induces a well-defined constitution through covalent self-assembly, and that the system can be steered, quantitatively and reversibly without significant fatigue, between two different constitutional states, respectively, polymeric and macrocyclic assemblies. The dynamic covalent polymeric assemblies were analysed by DOSY NMR and small angle neutrons scattering (SANS). Their dynamic behaviour as a function of the concentration and the temperature was demonstrated and characterized. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Two new ligands for carbonic anhydrase mimicry
Li, Xuehe,Gibb, Corinne L.D,Kuebel, Marie E,Gibb, Bruce C
, p. 1175 - 1182 (2001)
The syntheses of tris(2-nicotinic acid)methanol methyl ether 5 and tris(2-picolinic acid)methanol methyl ether 6, two tridentate ligands designed to also act as scaffolds for constructing chiral environments around their metal binding sites, is described. Improved yields for the essential lithiation-alkylation reactions that generate the trispyridyl core of these types of ligands are reported.
Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
, p. 3514 - 3523 (2020/10/09)
Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
Hemilabile Benzyl Ether Enables Γ-C(sp3)-H Carbonylation and Olefination of Alcohols
Tanaka, Keita,Ewing, William R.,Yu, Jin-Quan
supporting information, p. 15494 - 15497 (2019/10/16)
Pd-catalyzed C(sp3)-H activation of alcohol typically shows β-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct Γ- or δ-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of β-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.
