Iron-catalysis

In the case of a vanadium-catalyzed CDC reaction a Murahashi-style amine-metal co-ordination was proposed to assist in the metal-mediated SET/HAT events that lead to the iminium ion-metal complex subsequently the metal is re-oxidized by the terminal oxidant, but there was no experimental validation of this hypothesis. A similar mechanism involving amine-metal eo-ordination and metal oxidation while complexed to the iminium ion was proposed for a gold-catalyzed CDC reaction.  

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Plietker B (ed) (2008) Iron catalysis in organic chemistry, Wiley-VCH, Weinheim... 

High-valent iron-imido complexes have also been proposed as reaction intermediates in several reactions of the iron catalysis. Que and coworkers have provided evidence for Fe(IV) imide as a reaction intermediate in the reaction of [(6-PhTPA)-Fe°(CH3CN)2] " with PhI=NTs. Borovik and coworkers have also reported the formation of an amide product involving the generation of a putative iron(IV) imide [36] (Scheme 7). 

Scheme 28 Domino iron catalysis for cross-coupling of alkyl and aryl halides [90]...

Organolithium reagents47 instead of organoaluminum derivatives48, 9 have been used for the carbometallation of unactivated alkynes under iron catalysis (Scheme 9). Thus, variously substituted alkynes 30 and 32, bearing a tertiary... 

Iron catalysis in oxidation reactions with peroxides, both hydrogen peroxide and alkyl hydroperoxides, is frequently regarded as just a Haber-Weiss-type system where hydroxyl... 

However, arylmagnesium organometaUics can only be used in a few cases " like an iron-catalyzed homocoupling (equation 92) . Iron catalysis is further used for the dechlorination of electron-rich aryl chlorides by Grignard reagents . ... 

Recently, Fu and coworkers have shown that secondary alkyl halides do not react under palladium catalysis since the oxidative addition is too slow. They have demonstrated that this lack of reactivity is mainly due to steric effects. Under iron catalysis, the coupling reaction is clearly less sensitive to such steric influences since cyclic and acyclic secondary alkyl bromides were used successfully. Such a difference could be explained by the mechanism proposed by Cahiez and coworkers (Figure 2). Contrary to Pd°, which reacts with alkyl halides according to a concerted oxidative addition mechanism, the iron-catalyzed reaction could involve a two-step monoelectronic transfer. 

Iron-catalyzed alkenylation of Grignard reagents was used by Cahiez and Avedissian to prepare the pheromone of Argyroplace Leucotetra in three steps from l,2-( )-dichloro-ethene (Scheme 63). Two successive alkenylation reactions, the first involving a cobalt catalysis, the second an iron catalysis, allow one to obtain the desired product in 45% overall yield. 

Iron Catalysis in Organic Chemistry. Edited by Bernd Plietker Copyright 2008 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31927-5... 

Oxidative addition generally increases the oxidation state of the metal by two units and, based on the common oxidation states of iron, leads from iron(0) to iron(II) or iron(-II) to iron(0). The former represents the most widespread system for iron catalysis in organic synthesis but the latter also has enormous potential for applications (see Section 1.4). 

M. Broring, in Iron Catalysis in Organic Chemistry Reactions and Applications, ed. B. Plietker, Wiley-VCH, Weinheim, 2008, pp. 48-72. 

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