Zur Rolle von Organoferraten in eisenkatalysierten Kreuzkupplungen

Abstract

Bahnbrechende Studien zu Organoferraten haben gezeigt, dass koordinativ ungesättigte dreifach koordinierte σ‐Alkylferrate aktive Katalysatoren in Fe‐katalysierten Kreuzkupplungen mit Grignard‐Reagentien sind und dass ausgeprägte Lösungsmittel‐ und Gegenioneneffekte die Metallatspezifizierung und Katalysatoraktivität bestimmen. Dank moderner spektroskopischer Methoden könnten empfindliche Katalysatorzwischenstufen analysiert werden.

Iron‐Catalyzed Borylation of Propargylic Acetates for the Synthesis of Multisubstituted Allenylboronates

“…Based on previous studies, [13] we propose initial formation of [LFe n Et] complexes resulting from the reaction between the Grignard reagent and Fe(acac) 3 , [16] followed by transmetallation by B 2 pin 2 forming a nucleophilic boron species, LFe n Bpin. The formation of these complexes is promoted by the presence of TMEDA and led to a color change from orange to dark brown [17,18] . Coordination of the propargylic substrate 1 to the LFe n Bpin complex would give alkyne complex Int ‐A .…”

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…”

Copper(I) Catalyzed Decarboxylative Synthesis of Diareno[a,e]cyclooctatetraenes

“… 1 , 2 Applications span from size-switchable cavities 3 to molecular tweezers, 4 , 5 materials for energy storage, 6 , 7 force 8 , 9 and free volume probes, 10 adhesives, 11 and light-emitting devices. 12 − 15 Perhaps the most prominent implementations of the parent members, dibenzo[ a , e ]cyclooctatetraene (dbCOT, 2 ) 16 and dinaphto[ a , e ]cyclooctatetraene (dnCOT, 5 ), 17 are found in coordination chemistry as bis-η 2 ligands. 18 dbCOT was first developed as a catalyst-poison by Crabtree, 19 but more recently, both dbCOT and dnCOT have been shown to confer both enhanced stability and superior performance when used as ligands in several catalytic systems.…”

“…Diareno­[ a , e ]­cyclooctatetraenes and their derivatives comprise a remarkably useful class of functional molecules. , Applications span from size-switchable cavities to molecular tweezers, , materials for energy storage, , force , and free volume probes, adhesives, and light-emitting devices. − Perhaps the most prominent implementations of the parent members, dibenzo­[ a , e ]­cyclooctatetraene (dbCOT, 2 ) and dinaphto­[ a , e ]­cyclooctatetraene (dnCOT, 5 ), are found in coordination chemistry as bis-η 2 ligands . dbCOT was first developed as a catalyst-poison by Crabtree, but more recently, both dbCOT and dnCOT have been shown to confer both enhanced stability and superior performance when used as ligands in several catalytic systems. − Notable examples include iridium-catalyzed allylic substitutions, − iridium- and rhodium-catalyzed (5 + 2) cycloadditions, , a ruthenium-catalyzed oligomerization, and rhodium-catalyzed polymerization reactions .…”