Catalytic CO Homologation at Magnesium

The synthesis of C₂₊ molecules from C₁ sources is a critical technology for a sustainable chemical economy. Carbon monoxide (CO) is a key C₁ feedstock for processes such as the Fischer-Tropsch synthesis; however, achieving the reductive coupling of CO to C₂₊ products with selectivity is a major contemporary challenge. This report details the homologation of CO catalyzed by a homogeneous dipyrromethene magnesium alkyl complex, and a turnover strategy underpinned by the bulk industrial reagent triethylaluminum. Single-turnover experiments between the magnesium alkyl catalyst and CO resulted in a CO-homologated product. Subsequent reaction with triethylaluminum allowed isolation of bimetallic intermediates that provided experimental evidence for structural motifs in the calculated catalytic pathway. This work demonstrates a new approach to CO activation and catalysis using a main-group metal, operating in a mechanistically distinct regime from widespread transition-metal catalytic cycles.