The Role of Organoferrates in Iron‐Catalyzed Cross‐Couplings

Abstract

Recent groundbreaking studies on organoferrates have demonstrated that coordinatively unsaturated three‐coordinate‐σ‐alkylferrates are active catalysts in Fe‐catalyzed cross‐couplings with Grignard reagents and that pronounced solvent and counterion effects dictate metalate speciation and catalyst activity. Thanks to modern spectroscopic methods, sensitive catalyst intermediates could be analyzed.

Iron‐Catalyzed Cross‐Coupling of Propargyl Ethers with Grignard Reagents for the Synthesis of Functionalized Allenes and Allenols

“…In the iron‐catalyzed coupling reaction it is thought that the Grignard reagent initially reacts with the iron catalyst Fe(acac) 3 to generate a reduced organoiron complex, probably an “ate” complex. [ 17 , 18 ] Based on the observed transfer of chirality, the reaction is proposed to proceed via a syn ‐S N 2′ attack of the initially generated organoiron intermediate on substrate 1 (oxidative addition) to generate Int ‐B via Int ‐A (Scheme 5 ). Reductive elimination from Int ‐B would give trisubstituted allene product 2 with the observed axial chirality.…”

Iron‐Catalyzed Cross‐Coupling of Propargyl Ethers with Grignard Reagents for the Synthesis of Functionalized Allenes and Allenols

“…In the iron‐catalyzed coupling reaction it is thought that the Grignard reagent initially reacts with the iron catalyst Fe(acac) 3 to generate a reduced organoiron complex, probably an “ate” complex [17, 18] . Based on the observed transfer of chirality, the reaction is proposed to proceed via a syn ‐S N 2′ attack of the initially generated organoiron intermediate on substrate 1 (oxidative addition) to generate Int ‐B via Int ‐A (Scheme 5).…”

Some trends in sustainable catalysis development

“…Here, the groups of Fürstner, Bedford, and Neidig have made important contributions. 4) A noteworthy feature of simple iron salt-catalysed cross-coupling reaction is the use of N-methyl-2-pyrolidone (NMP), which is the most effective O-coordinating ligand to iron. However, NMP is reprotoxic, and the development of synthetic strategies that preclude safety concerns is an important goal of green chemistry.…”