139163-56-7Relevant articles and documents
The versatile, efficient, and stereoselective self-assembly of transition-metal helicates by using hydrogen-bonds
Telfer, Shane G.,Kuroda, Reiko
, p. 57 - 68 (2005)
A diverse range of dinuclear double-stranded helicates in which the ligand strand is built up by using hydrogen-bonding has been synthesized. The helicates, formulated as [Co2(L)2(L-H)2X 2], readily self-assemble from a mixture of a suitable pyridine-alcohol compound (L; for example, 6-methylpyridine-2-melhanol, 1), and a CoX2 salt in the presence of base. Nine such helicates have been characterized by X-ray crystallography. For helicates derived from the same pyridine-alcohol precursor, a remarkable regularity was found for both the molecular structure and the crystal packing arrangements, regardless of the nature of the ancillary ligand (X). A notable exception was observed in the solid-state structure of [Co2(1)2(1-H)2(NCS) 2] for which intermolecular nonbonded contacts between the sulfur atoms (S...S = 3.21 A) lead to the formation of 1D chains. Helicates derived from (R)-6-methylpyridine-2-methanol (2) are soluble in solvents such as CH3CN and CH2Cl2, and their self-assembly could be monitored in solution by 1H NMR, UV/Vis, and CD titrations. No intermediate complexes were observed to form in a significant concentration at any point throughout these titrations. The global thermodynamic stability constant of [Co2(2)2-(2-H)2(NO 3)2] was calculated from spectrophotometric data to be logβ = 8.9(8). The stereoisomerism of these helicates was studied in some detail and the self-assembly process was found to be highly stereoselective. The chirality of the ligand precursors can control the absolute configuration of the metal centers and thus the overall helicity of the dinuclear assemblies. Furthermore, the enantiomers of rac-6-methylpyridine-2-methanol (3) undergo a self-recognition process to form exclusively bomochiral helicates in which the four pyridine-alcohol units possess the same chirality.
Copper-catalyzed asymmetric reductions of aryl/heteroaryl ketones under mild aqueous micellar conditions
Etemadi-Davan, Elham,Fialho, David M.,Gadakh, Amol,Langner, Olivia C.,Lipshutz, Bruce H.,Sambasivam, Ganesh,Takale, Balaram S.
supporting information, p. 3282 - 3286 (2021/05/29)
Enantioselective syntheses of nonracemic secondary alcohols have been achieved in an aqueous micellar medium via copper-catalyzed (Cu(OAc)2·H2O/(R)-3,4,5-MeO-MeO-BIPHEP) reduction of aryl/heteroaryl ketones. This methodology serves as a green protocol to access enantio-enriched alcohols under mild conditions (0-22 °C) using a base metal catalyst, together with an inexpensive, innocuous, and convenient stoichiometric hydride source (PMHS). The secondary alcohol products are formed in good to excellent yields with ee values greater than 90%.
Multifaceted chelating μ-(η3:η3-antifacial)-(cis-C4R2H2) coordination motif in binuclear complexes
Liu, Cham-Chuen,Chan, Michael C. W.,Lo, Po-Kam,Lau, Kai-Chung,Yiu, Shek-Man
supporting information, p. 11056 - 11059 (2016/09/19)
A novel μ-C4R2H2 core structure (formed by an unprecedented regioselective, redox-neutral C(sp2)-C(sp2) coupling process) in binuclear group 4 complexes displays adaptable coordination and accommodates different metal sizes, and is sufficiently robust to promote interesting catalytic reactivity at the bimetallic centers.
