One of the major reasons for studying chemical kinetics is to use measurements of the macroscopic properties of a system, such as the rate of change in the concentration of reactants or products with time. 554-62-1, Name is Phytosphingosine, formurla is C18H39NO3. In a document, author is Le, Thien Phuc, introducing its new discovery. Category: chiral-catalyst.
A Cu-II complex of bisamidine ligand L-S, chirally modified naphtho[1,2-b:7,8-b’]dipyrroloimidazole (Naph-diPIM), catalyzes the enantioselective Friedel-Crafts (FC) reaction of indole (1a) with ethyl trifluoropyruvate (2) to give quantitatively the FC adduct 3a with a 98:2 S I R enantiomer ratio (er). The reaction shows no nonlinear effect (NLE) under the standard conditions of [1a] = [2] = 100 mM; [Cu(OTf)(2)] = [L-S + L-R] = 0.10 mM; CPME; and 0 degrees C irrespective of the catalyst aging temperature. A five-fold increase in the catalyst concentration (0.50 mM) changes the situation, leading to a strong (+)-NLE with phase separation of a white solid. The NLE is expressed by the Noyori-type mechanism: Aggregate of heterochiral dimer CuLSCuLR is separated from the reaction system (K-hetero > 1 > K-homo). Furthermore, a strong (+)-NLE is observed via a purple solid liberation even with [Cu-II] = 0.10 mM after the catalyst aging at 100 degrees C in the presence of an excess amount of chiral ligand. A mechanistic study has revealed i) that the sterically disfavored homochiral 1:2 complex CuLSLS is more stabilized by an intramolecular n-pi* interaction than the sterically favored heterochiral 1:2 complex CuLSLR and ii) that the (+)-NLE originates from the phase separation of heterochirally interacted (CuLSLSCuLRLR).
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Reference:
Chiral Catalysts,
,Chiral catalysts – SlideShare