Selectivity and Mechanism of Diene Cyclodimerization on Iron(0) Complexes

Abstract

The cyclodimerization of butadiene can be promoted by 1,4‐diaza‐1,3‐dieneiron(0) catalysts. At the moment of product formation, at least three diene units are present on the metal center; codimerizations suggest the presence of even four dienes.

Role of Homogeneous Catalysis in Oligomerization of Olefins : Focus on Selected Examples Based on Group 4 to Group 10 Transition Metal Complexes

“…Mainly monodentate donor ligands as PPh 3 have been investigated in Ziegler-Natta type systems comprising an iron{lll) precursor with an alkylaluminum as AIEt 3 . Bipyridine [106] followed by diimine ligands [107,108] were then described by Misono and tom Dieck, respectively, for the cyclodimerization of butadiene to cyclooctadiene and vinylcycloohexene. Ali these homogeneous systems are suggested to lead to an iron(O) active species as co-catalysts having reductive properties are mainly used such as AIEt 3 , or Grignard reagents.…”

Butadiene

“…The nickel catalyst can also be placed on a support so that it can be recycled (145). Many other type catalysts have been reported for this reaction (146). The linear 1,3,7-octatriene and its 1,3,6 isomer are also obtained by a Pd catalyzed dimerization (147)(148)(149)(150)(151).…”

Dimerisierung von Butadien, Codimerisierung von Butadien/1‐Buten und Direktverwertung des Raffinerie‐C4‐Schnitts an einem homogenen Eisen‐Katalysator

“…Es konnte gezeigt werden, daR Eisensalze wie FeCI, rnit stickstoffhaltigen Steuerliganden vom Typ der Diazadiene (DAD = RN = CR' = NR) Komplexe (DAD)FeCI, bilden, die sich leicht reduktiv zu katalytisch aktiven Fragmenten [DAD)Feo] umsetzen lassen. In Abhangigkeit von DAD lassen sich 1,3-Diene regio-und stereoselektiv zu cyclischen Dimeren verknupfen [2]. Innenstandige und terminale Alkine reagieren am gleichen Katalysator mit Butadien zu 1,4- [2].…”

“…In Abhangigkeit von DAD lassen sich 1,3-Diene regio-und stereoselektiv zu cyclischen Dimeren verknupfen [2]. Innenstandige und terminale Alkine reagieren am gleichen Katalysator mit Butadien zu 1,4- [2]. Wir nehmen daher an, daB ein homogener oder heterogenisierter molekularer Katalysator fur die Direktverwertung des C,-Schnitts optimiert werden kann, echte heterogene Katalysatoren sich hingegen sterisch hierfiir kaum ,,einstellen" lassen werden.…”