The Reaction of Active Zinc with Organic Bromides

Abstract

The oxidative addition of highly reactive zinc to organic bromides shows a pronounced structure−reactivity dependence, in contrast to that shown by other metals. The kinetic and LFER studies suggest a mechanism in which electron transfer (ET) is the rate-determining step of the reaction. Experiments carried out with radical clocks as well as the stereochemical outcome of the reaction support the presence of radicals. The reactivity profiles suggest that the ET has an important component of inner-sphere process in the reaction with alkyl bromides. In the case of aryl halides, Hammet plots are consistent with the participation of aryl halide radical anions as intermediates. The reaction contemplated here can be ascribed as another example of radical-mediated selective reaction, and it has straightforward synthetic applications. Some synthetic work was done in this direction, to demonstrate how this structure−reactivity dependence can be used to obtain selective organozinc formation in unsymmetrical dibromides.

Competitive kinetic study of the amination of organomagnesium and -zinc reagents with acetoneO-sulfonyloxime

“…1B) give values of ρ = −2.94 (r = 0.977, excluding 4-MeO group) and ρ = −0.84(r = 0.936) for reaction constants respectively. These correlations first support the assumption of first-order reaction in 35,36,42 organometallic reagent in the amination of Grignard reagents and zinc cyanocuprates. Second, the signs of the ρ values are negative, as expected, 49 -51 i.e.…”

An Efficient Synthesis of Diaryl Ketones by Iron‐Catalyzed Arylation of Aroyl Cyanides

“…[7] Recently we reported a general method for preparation of polyfunctional arylmagnesium halides of type 2 using I/Mg-or Br/Mg-exchange reactions.…”

Eine effiziente Synthese von polyfunktionalisierten Diarylketonen durch Eisen‐katalysierte Arylierung von Aroylcyaniden

“…[7] Kürzlich berichteten wir über eine generelle Methode zur Herstellung von polyfunktionellen Arylmagnesiumhalogeniden 2 durch einen I/Mg-oder Br/Mg-Austausch. [8] [9,10] Die Umsetzungen von PhMgCl mit PhCOCl bei 0 8C oder 20 8C in Gegenwart von [Fe(acac) [1a] Daher haben wir die Acylcyanide 1 als Acylierungsreagentien untersucht.…”