Effect of TMEDA on Iron-Catalyzed Coupling Reactions of ArMgX with Alkyl Halides

Abstract

A new reaction mechanism for the iron-catalyzed cross-coupling reaction of ArMgX with alkyl halides using (TMEDA)FeAr(2) and (TMEDA)Fe(Ar)Br is proposed on the basis of the isolation and reaction of these organoiron intermediates.

Solvent and TMEDA Effects on the Configurational Stability of Chiral Lithiated Aryloxiranes

“…[12b,d] We describe herein the effect of TMEDA on the configurational stability of a-lithiated trifluoromethyl-, chloro-, and phenylthio-substituted aryloxiranes in both coordinating and noncoordinating solvents. [14] The role of this ligand will also be tackled in light of the calculated barriers to inversion and activation parameters. A general trend becomes apparent for such reactive intermediates with a Abstract: The employment of hexane/ N,N,N',N'-tetramethylethylenediamine (TMEDA) dramatically hinders the racemization of those lithiated styrene oxides (trifluoromethyl-, chloro-, and phenylthio-substituted) that have been proven to be configurationally unstable in THF on the timescale of their re-A C H T U N G T R E N N U N G actions.…”

Cross-Coupling Reactions Catalyzed by Iron Group Metals and <i>N</i>-Heterocyclic Carbenes via Nonconventional Reaction Mechanisms

“…A radical type (II) (III) mechanism has been reported for iron catalyzed cross coupling reactions of alkyl halides with arylmagnesium reagents. 52 The catalytic cycle depicted on the left hand side of Figure 3 shows a canonical (0) (II) mechanism, which consists of the oxidative addition of an aryl halide to metal(0) intermediate D, transmetalation between arylmetal halide E and Ar 1 MgX, and reductive elimination of Ar 1 Ar 2 from diarylmetal(II) F. 53 We believe that the present reaction based on the metal uoride catalyst does not take place via the popular (0) (II) mechanism, but more likely via the higher valent metalate mechanism, which is analogous to those of cuprate mediated substitution reactions and catalytic cross coupling reactions. 54 The nal reductive elimination process in …”

Synthesis of Iron(III) Complex Bearing Tridentate β-Aminoketonato Ligand: Application to Iron-catalyzed Cross-coupling Reaction of Arylmagnesium Bromides with Alkyl Halides

“…These results indicated that the cross-coupling reaction catalyzed by complex 1 could involve a radical mechanism in the reaction of alkyl halide with the iron species. 6b, 15,16 In our system, the slow addition of phenylmagnesium bromide to the reaction mixture is unfavorable for the formation of the cross-coupled product (Table 1). This procedure resulted in increase of the formation of biphenyl, the homocoupled product.…”