Designed Iron Catalysts for Allylic C-H Functionalization of Propylene and Simple Olefins

Propylene gas is produced worldwide by steam cracking on million-metric-ton scale per year. It serves as a valuable starting material for pi-bond functionalization but is rarely applied in transition metal-catalyzed allylic C-H functionalization for fine chemical synthesis. Herein, we report that a newly-developed cationic cyclopentadienyliron dicarbonyl complex allows for the conversion of propylene to its allylic C-C bond coupling products under catalytic conditions. This approach was also found applicable to the allylic functionalization of simple alpha-olefins with distinctive branched selectivity. Experimental and computational mechanistic studies supported the allylic deprotonation of the metal-coordinated alkene as the turnover-limiting step and led to insights into the multifaceted roles of the newly designed ligand in promoting allylic C-H functionalization with enhanced reactivity and stereoselectivity.

Automated summary

A newly-developed cationic cyclopentadienyliron dicarbonyl complex enables the conversion of propylene to its allylic C-C bond coupling products under catalytic conditions. This approach is also applicable to the allylic functionalization of simple alpha-olefins with distinctive branched selectivity. Experimental and computational studies reveal the allylic deprotonation of the metal-coordinated alkene as the turnover-limiting step and provide insights into the multifaceted roles of the newly designed ligand in promoting allylic C-H functionalization with enhanced reactivity and stereoselectivity.