Imidazoline synthesis: mechanistic investigations show that Fe catalysts promote a new multicomponent redox reaction

Abstract

Integrated experimental and computational studies reveal a new mechanism for Fe-catalyzed imidazoline synthesis through combined nitrene transfer and acetonitrile attack of a styrenyl radical intermediate.

Cationic Divalent Metal Sites (M = Mn, Fe, Co) Operating as Both Nitrene-Transfer Agents and Lewis Acids toward Mediating the Synthesis of Three- and Five-MemberedN-Heterocycles

“…Starting with the introduction of iconic Fe porphyrinoid catalysts for the aziridination of olefins by Mansuy and co-workers, several other bioinspired Fe catalysts, , engineered hemoprotein enzymes, and even a single case of P450-mediated formation of an intermediate aziridine in benzastatin biosynthesis, have paved the way to an iron age of highly selective nitrene-transfer transformations . Yet, detailed investigations of in situ elaboration of amines or aziridines to other valuable heterocycles under iron nitrene-transfer catalysis have only recently started emerging . Notable are also efforts to generate disubstituted pyrrolidines by means of Fe-mediated intramolecular C–H bond amination or olefin hydroamination .…”

Unprotected amine transfer performed by non-heme iron(ii) complexes

“…Such a product was recently observed in the case of tosyl-protected nitrene transfer and characterized as an imidazoline compound by the group of Latour. 23 These results suggest that both protected and unprotected amine transfers may follow the same mechanistic pathway and open interesting perspectives for upcoming mechanistic studies. Finally, to avoid such acetonitrile incorporation, the reaction was also performed in a dichloromethane/methanol (98/2) solution under the same conditions, and ESI-MS analysis only showed the formation of an aziridine compound ( 3 ) at m / z 120.0807 (ESI† Fig.…”

Nitrene transfers mediated by natural and artificial iron enzymes

“…It is worth noting that related solvent interceptions of intermediates during nitrene transfer reactions have been very recently documented. 85,86 25°C, 4 h…”