Exploration of the Nature of the Anionic Ligands in Ruthenium Pre-Catalysts Designed for Asymmetric Olefin Metathesis

Ruthenium alkylidenes complexes are key components in the promotion of the highly important metathesis reaction. Throughout the years there have been extensive studies discussing the nature and impact of the surrounding ligands within the catalytic sphere of these complexes. Replacement of the commonly used chloride ligands in the known ruthenium alkylidenes by different halides and pseudo-halides showed that fine-tuning of the anionic ligands can lead to different reactivity and selectivity of the pre-catalysts.¹ We have recently demonstrated that asymmetric metathesis can be achieved by the facile installation of amino acids as chiral anionic ligands.² The use of readily available amino acids enables a simple protocol as well as easily tuned properties. Nonetheless, due to the dynamic nature of the anionic position,³ reduction of the lability of the carboxylate ligands was found to be crucial in improving the observed enantioselectivity. Therefore we are currently focusing on probing the dynamic nature of the anionic position and its role in the stability and reactivity of a variety of ruthenium complexes. Better understanding of the processes in which the anionic ligands are involved, will lead to the synthesis of a stable, enantioselective ruthenium complex bearing amino acid anionic ligands as chiral inducers.

References:

1 Anderson, E. B.; Buchmeiser, M. R. Synlett 2012, 2, 185.

2 Ivry, E.; Ben-Asuly, A.; Goldbergb, I.; Lemcoff, N. G. Chem. Commun. 2015, 51, 3870.

3 Tanaka, K.; Böhm, V. P. W.; Chadwick, D.; Roeper, M.; Braddock, D. C. Organometallics. 2006, 25, 5696.