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

Authors :: Hernán-Gómez A
Rodríguez M
Parella T
Costas M
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2019 Sep 23; Vol. 58 (39), pp. 13904-13911. Date of Electronic Publication: 2019 Aug 21.
Publication Year :: 2019
Abstract: Combining an electrophilic iron complex [Fe( <superscript>F</superscript> pda)(THF)] <subscript>2</subscript> (3) [ <superscript>F</superscript> pda=N,N'-bis(pentafluorophenyl)-o-phenylenediamide] with the pre-activation of α-alkyl-substituted α-diazoesters reagents by LiAl(OR <superscript>F</superscript> ) <subscript>4</subscript> [OR <superscript>F</superscript> =(OC(CF <subscript>3</subscript> ) <subscript>3</subscript> ] provides unprecedented access to selective iron-catalyzed intramolecular functionalization of strong alkyl C(sp <superscript>3</superscript> )-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.<br /> (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

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