28317-96-6Relevant articles and documents
Anion Receptor Design: Exploiting Outer-Sphere Coordination Chemistry to Obtain High Selectivity for Chloridometalates over Chloride
Carson, Innis,MacRuary, Kirstian J.,Doidge, Euan D.,Ellis, Ross J.,Grant, Richard A.,Gordon, Ross J.,Love, Jason B.,Morrison, Carole A.,Nichol, Gary S.,Tasker, Peter A.,Wilson, A. Matthew
, p. 8685 - 8692 (2015)
High anion selectivity for PtCl62- over Cl- is shown by a series of amidoamines, R1R2NCOCH2CH2NR3R4 (L1 with R1 = R4 = benzyl and R2 = R3 = phenyl and L3 with R1 = H, R2 = 2-ethylhexyl, R3 = phenyl and R4 = methyl), and amidoethers, R1R2NCOCH2CH2OR3 (L5 with R1 = H, R2 = 2-ethylhexyl and R3 = phenyl), which provide receptor sites which extract PtCl62- preferentially over Cl- in extractions from 6 M HCl solutions. The amidoether receptor L5 was found to be a much weaker extractant for PtCl62- than its amidoamine analogues. Density functional theory calculations indicate that this is due to the difficulty in protonating the amidoether to generate a cationic receptor, LH+, rather than the latter showing weaker binding to PtCl62-. The most stable forms of the receptors, LH+, contain a tautomer in which the added proton forms an intramolecular hydrogen bond to the amide oxygen atom to give a six-membered proton chelate. Dispersion-corrected DFT calculations appear to suggest a switch in ligand conformation for the amidoamine ligands to an open tautomer state in the complex, such that the cationic N-H or O-H groups are also readily available to form hydrogen bonds to the PtCl62- ion, in addition to the array of polarized C-H bonds. The predicted difference in energies between the proton chelate and nonchelated tautomer states for L1 is small, however, and the former is found in the X-ray crystal structure of the assembly [(L1H)2PtCl6]. The DFT calculations and the X-ray structure indicate that all LH+ receptors present an array of polarized C-H groups to the large, charge diffuse PtCl62- anion resulting in high selectivity of extraction of PtCl62- over the large excess of chloride. (Figure Presented).
Intramolecular Friedel-Crafts Acylation Reaction Promoted by 1,1,1,3,3,3-Hexafluoro-2-propanol
Motiwala, Hashim F.,Vekariya, Rakesh H.,Aubé, Jeffrey
, p. 5484 - 5487 (2015/11/18)
Simple dissolution of an arylalkyl acid chloride in 1,1,1,3,3,3-hexafluoro-2-propanol promotes an intramolecular Friedel-Crafts acylation without additional catalysts or reagents. This reaction is operationally trivial in both execution and product isolation (only requiring concentration followed by purification) and accommodates a broad range of substrates. Preliminary studies that bear upon potential reaction mechanisms are reported.
The development of the first catalyzed reaction of ketenes and imines: Catalytic, asymmetric synthesis of β-lactams
Taggi, Andrew E.,Hafez, Ahmed M.,Wack, Harald,Young, Brandon,Ferraris, Dana,Lectka, Thomas
, p. 6626 - 6635 (2007/10/03)
We report practical methodology for the catalytic, asymmetric synthesis of β-lactams resulting from the development of a catalyzed reaction of ketenes (or their derived zwitterionic enolates) and imines. The products of these asymmetric reactions can serve as precursors to a number of enzyme inhibitors and drug candidates as well as valuable synthetic intermediates. We present a detailed study of the mechanism of the β-lactam forming reaction with proton sponge as the stoichiometric base, including kinetics and isotopic labeling studies. Stereochemical models based on molecular mechanics (MM) calculations are also presented to account for the observed stereoregular sense of induction in our reactions and to provide a guidepost for the design of other catalyst systems.
