Kumada Cross Coupling Reaction And Ring Opening Polymerization Of ε-Caprolactone Catalyzed By Iron Compounds

A series of iron compounds were synthesized by the reaction with iron salts and imidazole salts or N-heterocyclic carbene ligands,and fully characterized by elemental analysis,and some of them by X-ray structural determination.Preliminary studies show that these iron compounds can catalyze the Kumada cross-coupling reaction.Otherwise, a new monohalogen monoalkyloxide iron(â…¡)compound was synthesized,and fully characterized by elemental analysis and X-ray structural determination.Preliminary studies show that the iron(â…¡)compound can be used as a single component catalyst for the ring-opening polymerization ofε-caprolactone.1.The reaction of anhydrous FeCl₃ with different imidazole salts afforded four ionic liquid compounds of iron(â…¢),(HIPrFeCl₄,1;HMesFeCl₄,2;HtBuFeCl₄,3;HiPrFeCl₄, 4).All of them were characterized by elemental analysis and compound 1 was further characterized by single X-ray structural determination.2.The reaction of anhydrous FeCl₂ and FeBr₂ with 1,3-di-(2,6-diisopropanylphenyl) imidazole chloride salts afforded two ionic liquid compounds of iron(â…¡),(HIPrFeCl₃,5; HIPrFeBr₃,6).All of them were characterized by elemental analysis and single X-ray structural determination.3.The reaction of HIPrFeBr₃(6)with one equivalent of carbene in situ generated from 1,3-di-(2,6-di-isopropanylphenyl)imidazole chloride salts afforded a first monocarbene iron(â…¡)compound of HIPr(IPr)FeBr₃(7),which is Stabilized by one imidazole salt and one N-heterocyclic carbene ligand.Compound 7 was characterized by elemental analysis and single X-ray structural determination. 4.The reaction of anhydrous FeBr₂ with three equivalent of in situ generated (CH₃)₂NCH₂CH₂OLi afforded a first monohalogen monoalkyloxide iron(â…¡)compound {FeBrLi₂[N(CH₃)₂CH₃CH₂O)]₃}₂(8).The compound was characterized by elemental analysis and single X-ray structural determination.5.It was found that compounds 1-7 were efficient catalysts for Kumada cross-coupling reaction of aryl Grignard with secondary alkyl halides bearingβ-hydrogens.The structure of these compounds show strongly effect on their catalytic activity.The active order is 4＞2≈3＞5＞1＞7＞6.The catalytic mechanism has been primarily studied.6.The catalytic activity of the monohalogen monoalkyloxide iron(â…¡)compound 8 for ring-opening polymerization(ROP)ofε-CL was studied,and it was found that the compound was an efficient initiator for the ROP ofε-CL.To the best of our knowledge, it was the most active initiator for the ROP ofε-CL among reported iron compound.