Showing papers by "Donna G. Blackmond published in 2005"
TL;DR: Reaction progress kinetic analysis to obtain a comprehensive picture of complex catalytic reaction behavior is described to help describe the driving forces of a reaction and may be used to help distinguish between different proposed mechanistic models.
Abstract: Reaction progress kinetic analysis to obtain a comprehensive picture of complex catalytic reaction behavior is described. This methodology employs in situ measurements and simple manipulations to construct a series of graphical rate equations that enable analysis of the reaction to be accomplished from a minimal number of experiments. Such an analysis helps to describe the driving forces of a reaction and may be used to help distinguish between different proposed mechanistic models. This Review describes the procedure for undertaking such analysis for any new reaction under study.
513 citations
TL;DR: The mechanistic details of the Cu-catalyzed amidation of aryl iodides are presented and the kinetic data suggest that the diamine ligand prevents multiple ligation of the amide.
Abstract: The mechanistic details of the Cu-catalyzed amidation of aryl iodides are presented. The kinetic data suggest that the diamine ligand prevents multiple ligation of the amide. The formation of an amidocuprate species external to the catalytic cycle helped to rationalize the dependence on diamine concentration and the inverse dependence on amide concentration at low diamine concentrations. The intermediacy of a Cu(I) amidate was established through both its chemical and kinetic competency.
241 citations
TL;DR: The present mechanistic study, which includes the NMR characterization of the precatalysts, kinetic measurements with focus on nonlinear effects, and DFT calculations, constitutes a first step in understanding this hydrogenation system.
Abstract: Whereas recent synthetic studies concerning Rh-catalyzed olefin hydrogenation based on BINOL-derived monodentate phosphites have resulted in an efficient and economically attractive preparative method, very little is known concerning the source of the unexpectedly high levels of enantioselectivity (ee often 90-99%). The present mechanistic study, which includes the NMR characterization of the precatalysts, kinetic measurements with focus on nonlinear effects, and DFT calculations, constitutes a first step in understanding this hydrogenation system. The two most important features which have emerged from these efforts are the following: (1) two monodentate P-ligands are attached to rhodium, and (2) the lock-and-key mechanism holds, in which the thermodynamics of Rh/olefin complexation with formation of the major and minor diastereomeric intermediates dictates the stereochemical outcome. The major diastereomer leads to the favored enantiomeric product, which is opposite to the state of affairs in classical Rh-catalyzed olefin hydrogenation based on chiral chelating diphosphines (anti lock-and-key mechanism as proposed by Halpern).
111 citations
TL;DR: In this paper, a kinetische Reaktionsfortschrittsanalyse lasst sich ein umfassendes mechanistisches Bild of komplexen katalytischen Reaktion systemen erhalten.
Abstract: Durch eine kinetische Reaktionsfortschrittsanalyse lasst sich ein umfassendes mechanistisches Bild von komplexen katalytischen Reaktionssystemen erhalten. Die beschriebene Methodik nutzt In-situ-Messungen in Kombination mit einfachen mathematischen Prozeduren zur Konstruktion “graphischer Geschwindigkeitsgleichungen”, die eine Reaktionsanalyse bei minimaler Zahl an Experimenten ermoglichen. Eine solche Analyse kann helfen, die Triebkrafte einer chemischen Reaktion zu bestimmen und zwischen vorgeschlagenen mechanistischen Modellen zu unterscheiden. Dieser Aufsatz beschreibt einen “Fahrplan”, nach dem sich jede beliebige Reaktion analysieren lasst.
84 citations
TL;DR: In this article, reaction progress kinetic analysis of the poly(l)-leucine (PLL)-catalyzed epoxidation of substituted chalcones 1a−1c helps to refine an earlier mechanistic proposal by demonstrating that the reaction proceeds via reversible addition of chalcone to a PLL-bound hydroperoxide, forming a fleeting hydroperoxy enolate species.
38 citations
TL;DR: A spectacular salt effect in the kinetic resolution of (+/-)-1-phenylethylamine is described, which leads to an increase in reactivity, high levels of selectivity, and a complete reversal of the stereoselectivity.
Abstract: We have described a spectacular salt effect in the kinetic resolution of (±)-1-phenylethylamine, which leads to an increase in reactivity, high levels of selectivity, and a complete reversal of the stereoselectivity. By tuning the reaction conditions, we were able to increase the selectivity factor of (1S,2S)-1 to s = 115.
38 citations
TL;DR: In this paper, reaction progress kinetic analysis is described to obtain a comprehensive picture of complex catalytic reaction behavior. But the analysis of the reaction can be accomplished from a minimal number of experiments and may be used to help distinguish between different proposed mechanistic models.
Abstract: Reaction progress kinetic analysis to obtain a comprehensive picture of complex catalytic reaction behavior is described. This methodology employs in situ measurements and simple manipulations to construct a series of graphical rate equations that enable analysis of the reaction to be accomplished from a minimal number of experiments. Such an analysis helps to describe the driving forces of a reaction and may be used to help distinguish between different proposed mechanistic models. This Review describes the procedure for undertaking such analysis for any new reaction under study.
17 citations