Electrophilic Iron Catalyst Paired with a Lithium Cation Enables Selective Functionalization of Non‐Activated Aliphatic C−H Bonds via Metallocarbene Intermediates

Abstract Combining an electrophilic iron complex [Fe( F pda)(THF)] 2 ( 3 ) [ F pda= N , N ′‐bis(pentafluorophenyl)‐ o ‐phenylenediamide] with the pre‐activation of α‐alkyl‐substituted α‐diazoesters reagents by LiAl(OR F ) 4 [OR F =(OC(CF 3 ) 3 ] provides unprecedented access to selective iron‐catalyzed intramolecular functionalization of strong alkyl C(sp 3 )−H bonds. Reactions occur at 25 °C via α‐alkyl‐metallocarbene intermediates, and with activity/selectivity levels similar to those of rhodium carboxylate catalysts. Mechanistic investigations reveal a crucial role of the lithium cation in the rate‐determining formation of the electrophilic iron‐carbene intermediate, which then proceeds by concerted insertion into the C−H bond.