1557174-86-3Relevant academic research and scientific papers
Side-bridged cyclam transition metal complexes bearing a phenolic ether or a phenolate pendent arm
Mewis, Ryan E.,Archibald, Stephen J.
, p. 578 - 589 (2019)
Side-bridged cyclam transition metal complexes (M = Ni(II), Cu(II) and Zn(II)) bearing a phenolic ether or phenolate pendent arm have been synthesised. For [NiL1]+ and [CuL1]+, evidence for a phenoxyl radical wa
Chiral 1,2-cyclohexane-bridged bis-NHC palladium catalysts for asymmetric Suzuki-Miyaura coupling: Synthesis, characterization, and steric effects on enantiocontrol
Li, Yinle,Tang, Junkai,Gu, Jun,Wang, Quanrui,Sun, Peipei,Zhang, Dao
, p. 876 - 884 (2014/03/21)
The series of chiral 1,2-cyclohexane-bridged bis-N-heterocyclic carbene ligand precursors H2[(1R,2R)-(1a-i)]Br with different substituent groups and their neutral and cationic diaqua palladium complexes, namely {Pd[(1R,2R)-(1a-i)]Br2} (2a-i), {Pd[(1R,2R)-(1a)]X2} (X = Cl (3), OAc (4-OAc), OC(O)CF3 (4-OCH(O)CF3)), and {Pd[(1R,2R)-(LOMe)](OH2)2}X2 (X = OTf (5-OTf), SbF6 (5-SbF6)) have been prepared in moderate to good yields. These chiral palladium complexes were fully characterized by elemental analysis, high-resolution mass spectra, 1H and 13C NMR, and optical rotation determinations. The crystal structures of the chiral complexes 2a and 5-OTf were further confirmed to adopt a distorted-square-planar coordination geometry around the palladium center. The obtained chiral NHC-Pd compounds were able to catalyze the asymmetric Suzuki-Miyaura couplings of aryl halides with arylboronic acids in good yields (up to 96%) and moderate enantioselectivities (up to 64% ee). The coligand and steric effects were studied carefully. The coligands, including Br-, Cl-, AcO-, CF3COO-, and water molecules, have little influence on the catalytic results. However, a strong steric effect of the two aromatic substituents R on the enantiocontrol has been proved in the catalytic asymmetric Suzuki-Miyaura coupling reaction. The highest enantioselectivity of 64% ee could be achieved under the standard reaction conditions.
