Ligand coupling

Biphenyl formation by the ligand coupling of triphenylbismuth is promoted by Pd(OAc) [418],... 

These carbonyl chloride-activated carriers are unstable on storage, so ligand coupling to them has to be undertaken immediately after chemisorption of the copolymer. To overcome this drawback, more stable activated carriers have been synthesized by treating aminopropyl-silicas with poly(p-nitrophenyl acrylate) and acetic anhydride. 

Kragl and Dreisbach (1996) have carried out the enantioselective addition of diethyl zinc to benzaldehyde in a continuous asymmetric membrane reactor using a homogeneous soluble catalyst, described in their paper. Here a,a-diphenyl-L-proline was used as a chiral ligand, coupled to a copolymer made from 2-hydroxy ethyl methacrylate and octadecyl methacrylate, which had a sufficiently high molecular weight to allow separation by ultra-filtration (U/F). The solvent-stable polyaramide U/F Hoechst Nadir UF PA20 retained more than 99.8% of the catalyst. The ee was 80 %, compared to 98 % for a noncoupled catalyst. 

Dendrimer-PEG3-Ligand coupled through triazole linkage... 

Ligand coupling via an ether or secondary amine linkage... 

The imidazole carbamate group is more stable to hydrolysis in aqueous buffer than the NHS-carbonate group, which is similar in reactivity to an NHS ester. However, this means that the imidazole carbamate also is slower to react and couple with amines. NHS-carbonate reactions usually go to completion within 1-2 hours at room temperature, whereas imidazole carbamates typically require higher pH conditions and overnight incubations to get maximal yield of ligand coupling. 

CARRUTHERS Cycloaddition Reactions in Organic Synthesis CLARIDGE High-Resolution NMR Techniques in Organic Chemistry FINET Ligand Coupling Reactions with Heteroatomic Compounds GAWLEY AUBE Principles of Asymmetric Synthesis... 

The progress with phosphorescent blue emitters suggests that it may be quite possible to achieve high-efficiency blue phosphorescent candidates by carefully designing the proper ligands coupled with appropriate selection of auxiliary ligands. 

The reactions involved are unimolecular, and the cyclohexenyl derivative 3 undergoes solely the spontaneous heterolysis while both spontaneous heterolysis and ligand coupling occur with the iodane 14. The relative contributions of the two reactions of 14 depend on the solvent polarity. The results summarized in Table I show that the iodonium ion and the counteranion are in equilibrium with the hypervalent adduct, X3-iodane. The equilibrium constants depend on the identity of the anion and the solvent employed, and the iodane is less reactive than the free iodonium ion as the k /k2 raios demonstrate. Spontaneous heterolysis of 3 occurs more than 100 times as fast as th t of the adduct 14 as observed in methanol the leaving ability of the iodonid group is lowered by association by more than 100 times. 

Scheme 6 shows a novel C-P bond forming reaction, in which the ligand coupling of an alkyne and a tertiary phosphine on palladium metal occurs. It was also considered very important that a C-P bond could be formed by the addition of a phosphorous reagent to unsaturated compounds. 

Schuber F. Chemistry of ligand-coupling to liposomes. In Philippot JR, Schuber F, eds. Liposomes as Tools in Basic Research and Industry. Boca Raton CRC Press, 1995 21. 

The NMR data for the diynyl ligands in LnM C=CC=CH can usually be assigned unequivocally on the basis of 7(CH) coupling constants [and J CP) in the case of metal centres bearing phosphine co-ligands]. Coupling constants to Sn, and nuclei have also been employed. In general, values... 

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