387827-64-7Relevant articles and documents
Exploiting the Reactivity of Fluorinated 2-Arylpyridines in Pd-Catalyzed C-H Bond Arylation for the Preparation of Bright Emitting Iridium(III) Complexes
Boyaala, Rabab,Peng, Marie,Tai, Wun-Shan,Touzani, Rachid,Roisnel, Thierry,Dorcet, Vincent,Chi, Yun,Guerchais, Véronique,Doucet, Henri,Soulé, Jean-Fran?ois
, p. 13898 - 13911 (2020)
Pd-catalyzed C-H bond arylation applied to 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine (1) and 2-(3,5-difluorophenyl)-5-(trifluoromethyl)pyridine (5) allows the access to two families of Ir(III) complexes, charge-neutral and cationic species. The reaction is regioselective since only the C3- or C4-position of the fluorinated phenyl ring of 1 or 5 is readily functionalized - namely the C-H bond flanked by the two fluorine atoms which is the most acidic - which allows the electronic control of the reactive site. A range of electron-withdrawing (CN, CO2Et, C(O)Me) substituents on the aryl group has been incorporated leading to the pro-ligands (1, Ar-2,4-dFppy; 2, Ar = p-C6H4-CN; 3, Ar = p-C6H4-CO2Et; 4, Ar = p-C6H4-C(O)Me; 5, and Ar-3,5-dFppy; 6, Ar = p-C6H4-CO2Et). The unsubstituted complexes F1/G1 and F1/G5 featuring 1 and 5, respectively, as C^N ligands are used as reference complexes. The families of five charge-neutral [Ir(C^N)2(N^O)] complexes (C^N is 2-(5-aryl-(4,6-difluorophenyl)-5-(trifluoromethyl)pyridinato (F2-F4), and 2-(4-aryl-(3,5-difluorophenyl)-5-(trifluoromethyl)pyridinato (F5-F6), N^O = 2-picolinate) and five cationic [Ir(C^N)2(N^N)]PF6 complexes (N^N = dmbpy is 4,4′-dimethyl-2,2′-bipyridine) (G2-G6) were synthesized, and their structural and photophysical properties were studied with comparison to the unsubstituted analogues used as reference complexes. The appended aryl group provides large steric bulk as the biaryl fragment is twisted as shown by the X-ray crystal structures of F2, F5, F6, G3, and G5. These latter complexes display a wide variety of different Ir···Ir intermetallic distances in crystals, from 8.150 ? up to 15.034 ?. Moreover, the impact on the emission energy is negligible, as a result of the breaking of the conjugation between the two aryl groups. Charge-neutral complexes [Ir(C^N)2(N^O)] (N^O = 2-picolinate) show bright luminescence: F2-F4 (λem = 495-499 nm) are blue-green emitters, whereas F5 and F6 (λem = 537, 544 nm), where the fluorine substituents are located at the C3- and C5-positions, emit in the green region of the visible spectrum. In all cases, a unitary photoluminescence quantum yield is found. The improvement of φ might be explained by an increase of the radiative rate constant due to a higher degree of rigidity of these congested molecules, compared to the unsubstituted complex F1. The same trends are observed for the family of complexes G. Complexes G1-G4 exhibit blue photoluminescence, and G5 and G6 lead to a red-shifted emission band, as also found for the related complexes F5 and F6 due to the similar fluorine substitution pattern. Their emission quantum yields are remarkably high for charged complexes in the CH2Cl2 solution. These results showed that Pd-catalyzed C-H bond arylation is a valuable synthetic approach for designing efficient emitters with tunable photophysical properties.
A Water-Soluble Iridium Photocatalyst for Chemical Modification of Dehydroalanines in Peptides and Proteins
van Lier, Roos C. W.,de Bruijn, A. Dowine,Roelfes, Gerard
supporting information, p. 1430 - 1437 (2020/12/11)
Dehydroalanine (Dha) residues are attractive noncanonical amino acids that occur naturally in ribosomally synthesised and post-translationally modified peptides (RiPPs). Dha residues are attractive targets for selective late-stage modification of these complex biomolecules. In this work, we show the selective photocatalytic modification of dehydroalanine residues in the antimicrobial peptide nisin and in the proteins small ubiquitin-like modifier (SUMO) and superfolder green fluorescent protein (sfGFP). For this purpose, a new water-soluble iridium(III) photoredox catalyst was used. The design and synthesis of this new photocatalyst, [Ir(dF(CF3)ppy)2(dNMe3bpy)]Cl3, is presented. In contrast to commonly used iridium photocatalysts, this complex is highly water soluble and allows peptides and proteins to be modified in water and aqueous solvents under physiologically relevant conditions, with short reaction times and with low reagent and catalyst loadings. This work suggests that photoredox catalysis using this newly designed catalyst is a promising strategy to modify dehydroalanine-containing natural products and thus could have great potential for novel bioconjugation strategies.
Stereoselective Preparation of C-Aryl Glycosides via Visible-Light-Induced Nickel-Catalyzed Reductive Cross-Coupling of Glycosyl Chlorides and Aryl Bromides
Mou, Ze-Dong,Wang, Jia-Xi,Zhang, Xia,Niu, Dawen
supporting information, p. 3025 - 3029 (2021/05/27)
A nickel-catalyzed cross-coupling reaction of glycosyl chlorides with aryl bromides has been developed. The reaction proceeds smoothly under visible-light irradiation and features the use of bench-stable glycosyl chlorides, allowing the highly stereoselective synthesis of C-aryl glycosides. (Figure presented.).
