Iron(III)-catalyzed synthesis of multi-substituted imidazoles via [3+2] cycloaddition reaction of nitroolefins and N-aryl benzamidines

A novel and efficient iron(III)-catalyzed synthesis of multi-substituted imidazoles via [3+2] cycloaddition of nitroolefins and N-aryl benzamidines under the air atmosphere had been developed. This methodology is convenient, atom-economical, general, and eco-friendly in good yields and prefect regioselectivities.     

Iron-catalyzed bromination of aryl azides by N-bromosuccinimide:Efficient method for the synthesis of brominated aryl azides

An efficient and mild protocol for bromination of aryl azides with N-bromosuccinimide（NBS） under FeCl₃ catalysis in 1,2- dichloroethane was developed.It is proved to be an efficient method for obtaining brominated aryl azides.     

Recent advances on iron-catalyzed coupling reactions involving organolithium reagents

Several iron-catalyzed cross- and homo-coupling reactions involving organolithiums were developed to form diverse carbon-carbon bonds. The usefulness of this protocol was demonstrated by producing gram-scale products in good yields.     

Direct alkylation of thiophenes via bis-coupling with vinyl acetates

A novel direct alkylation of thiophenes via bis-coupling with vinyl acetates has been developed. To the best of our knowledge, this represents the first report of the iron-catalysed coupling of two thiophenes with vinyl groups. Utilizing earth-abundant, inexpensive, and non-toxic iron catalysts, this methodology converts simple thiophenes to symmetrical dithienylethane derivatives under mild conditions in one step.     

Iron-catalyzed three-component coupling of aldehyde, alkyne, and amine under neat conditions in air

Various iron-salts (and complexes) and especially iron(III) chloride catalyzed the three-component coupling of aldehyde, alkyne, and amine to generate propargylic amines with high efficiency under neat conditions in air. The iron-catalyzed reaction is particularly effective for reactions involving aliphatic aldehydes. The reaction is not sensitive to and occurs smoothly in water and in air. No additional co-catalyst or activator is required.     

Iron-mediated remote C–H bond benzylation of 8-aminoquinoline amides

An efficient and convenient method for C5-benzylation of quinoline frameworks is developed with the using of inexpensive FeCl₃ catalyst. A range of N-bisbenzylic and N-monobenzylic sulfonamides smoothly react with aliphatic amides and aromatic amides, giving the corresponding products in moderate to excellent yields.     

Direct synthesis of 2,4,5-trisubstituted imidazoles and di/tri-substituted pyrimidines via cycloadditions of α,β-unsaturated ketones/aldehydes and N′-hydroxyl imidamides

An efficient route for the synthesis of 5-acetylimidazoles and di/trisubstituted pyrimidines via iron-catalyzed cross-dehydrogenative coupling (CDC), with excellent tolerance and yields, has been developed. In this report, α,β-unsaturated aldehydes/ketones and N′-hydroxyl imidamides undergo [3+2] and [3+3] cycloadditions in two processes, involving iron-mediated Michael reaction, Robinson Annulation and 1,5-electrocyclization.     

Iron(III)-catalyzed synthesis of 3-aroylimidazo[1,2-a]pyridines from 2-aminopyridines and ynals

An efficient iron-catalyzed intermolecular aminooxygenation of 2-aminopyridines with a wide range of ynals has been developed. 3-Aroylimidazo[1,2-a]pyridines containing various functional groups are synthesized under the standard conditions. The transformation is conducted in simple conditions and forms products in good yields.     

Iron-catalyzed CC bond activation/CO bond formation: Direct conversion of ketones to esters

The iron-catalyzed oxidative activation of the (O)CC bond in ketones has been developed. This method enables direct synthesis of esters by the reaction between ketones and alcohols via conversion of the (O)CC bond to the (O)CO bond. The reaction runs selectively: the (O)CC_Alkyl bond is activated, while the (O)CC_Aryl bond remains intact (i.e., iron-catalyzed intermolecular anti-Baeyer-Villiger activation of the (O)CC bond). The reaction conditions are carefully optimized and allow the production of esters with yields of up to 95%. The method is based on the inexpensive and commercially available catalyst (FeCl₃), oxidant ((NH₄)₂S₂O₈), and solvent (DCE) without using any ligands or additives.     

An unprecedented iron-catalyzed cross-coupling of primary and secondary alkyl Grignard reagents with non-activated aryl chlorides

The use of N-heterocyclic carbene ligands in the iron-catalyzed cross-coupling of alkyl Grignards has allowed, for the first time, coupling of non-activated, electron rich aryl chlorides. Surprisingly, the tetrahydrate of FeCl₂ was found to be a better pre-catalyst than anhydrous FeCl₂. Primary Grignard reagents coupled in excellent yields while secondary Grignard reagents coupled in modest yields. The use of acyclic secondary Grignard reagents resulted in the formation of isomers in addition to the desired product. These isomeric products were formed via reversible β-hydrogen elimination, indicating that the cross-coupling proceeds through an ionic pathway.