Camphor-Based NHC Ruthenium Catalysts in AROCM: Influence of Catalyst Structure on Enantio- and E / Z Selectivity

Abstract

The development of stereoselective olefin metathesis remains a key challenge in modern catalysis, particularly in achieving simultaneous control over the enantioselectivity and Z-selectivity. In this study, a new class of camphor-derived chiral NHC ruthenium complexes was designed, synthesized, and evaluated in asymmetric ring-opening cross-metathesis. Systematic modification of the ligand architecture enabled a detailed investigation of steric and electronic effects on catalytic performance. The prepared catalyst series exhibited high activity in asymmetric ring-opening cross-metathesis (AROCM) reactions, with distinct trends observed between substituent size, catalyst reactivity, and stereoselectivity. While most complexes favored the formation of E-isomers, selected systems provided moderate to high enantioselectivity for Z products. Catechodithiolate-modified catalysts displayed a significant enhancement in Z-selectivity and enantioselectivity, achieving up to 99% ee, albeit at the expense of the catalytic activity. These findings highlight the critical role of ligand design in tuning catalyst performance and provide valuable insights into the structure–selectivity relationships governing asymmetric Z-selective olefin metathesis.