Elucidating Dramatic Ligand Effects on SET Processes: Iron Hydride versus Iron Borohydride Catalyzed Reductive Radical Cyclization of Unsaturated Organic Halides

Sara Kyne (1) , Martin Clémancey (2) , Geneviève Blondin (2) , Etienne Derat (1) , Louis Fensterbank (1) , Anny Jutand (3) , Guillaume Lefèvre (4) , Cyril Ollivier (1)

1 IPCM - Institut Parisien de Chimie Moléculaire
2 LCBM - UMR 5249 - Laboratoire de Chimie et Biologie des Métaux
3 PASTEUR - Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640)
4 LCMCE - Laboratoire de Chimie Moléculaire et de Catalyse pour l'Energie (ex LCCEF)

An iron(II) borohydride complex ([(η1-H3BH)FeCl(NCCH3)4]) is employed as the precatalyst in iron-catalyzed radical cyclizations of unsaturated organic halides in the presence of NaBH4. Mechanistic investigations have established that the ligand bound to the metal center (acetonitrile versus ethylenebis(diphenylphosphine) (dppe)) plays a crucial role in the structure and reactivity of the active anionic iron(I) hydride ([HFeCl(dppe)2]−) and borohydride ([(η1-H3BH)FeCl(NCCH3)4]−) with unsaturated haloacetals. This work provides new insights into iron(I) hydride and borohydride species and their potential implication in single-electron processes.

Domaines: Chimie; Chimie organique; Catalyse

Sara Kyne, Martin Clémancey, Geneviève Blondin, Etienne Derat, Louis Fensterbank, et al.. Elucidating Dramatic Ligand Effects on SET Processes: Iron Hydride versus Iron Borohydride Catalyzed Reductive Radical Cyclization of Unsaturated Organic Halides. Organometallics, 2017, 37, pp.761-771. ⟨10.1021/acs.organomet.7b00603⟩. ⟨cea-01608951⟩