Achieving Z-selective catalysts has been a major goal in olefin metathesis [1]. In contrast to the case for molybdenum and tungsten [2], straightforward modification of the monoanionic ligands of Grubbs catalysts for years led to only low or moderate Z-selectivity, with high selectivity requiring a particular bidentate NHC-adamantyl ligand [3]. Guided by DFT calculations, we have discovered that non-selective Grubbs-type catalysts can be modified to become highly Z-selective by replacing one of the two chlorides with a sterically demanding thiolate (1, Figure 1) [4]. The monothiolate Ru catalysts share mechanism with the standard Grubbs catalysts and coordinate the substrate olefin anti to the neutral donor ligand [5], in contrast to the syn-binding seen in other highly Z-selective Ru-based catalysts [6, 7]. Replacing the second chloride ligand of 1 by isocyanate results in a catalyst (2) with an unprecedented robustness, tolerating air and acids [8]. Increasing the steric bulk of the aryl group (Ar) in para position of the benzene thiolate gives catalysts (3) giving up to &gt; 97 % Z-selectivity in metathesis coupling reactions of 1-alkenes. Catalysts 1-3 also perform Z-selective ring-closing metathesis and ring-opening metathesis polymerization, and their performance will be discussed and compared to that of other recently developed Z-selective olefin metathesis catalysts. References [1] A. Fürstner, Science 2013, 341, 1357. [2] D. V. Peryshkov, R. R Schrock, M. K. Takase, P. Mueller, A. H. Hoveyda J. Am. Chem. Soc. 2011, 133, 20754. [3] B. K. Keitz, K. Endo, P. R. Patel, M. B. Herbert, R. H. Grubbs J. Am. Chem. Soc. 2012, 134, 693. [4] G. Occhipinti, F. R. Hansen, K. W. Törnroos, V. R. Jensen J. Am. Chem. Soc. 2013, 135, 3331. [5] J. W. Nelson, L. M. Grundy, Y. Dang, Z.-X. Wang, X. Wang, Organometallics 2014, 33, 4290. [6] P. Liu, X. Xu, X. Dong, B. K. Keitz, M. B. Herbert, R. H. Grubbs, K. N. Houk J. Am. Chem.Soc. 2012, 134, 1464. [7] R. K. M. Khan, S. Torker, A. H. Hoveyda J. Am. Chem. Soc. 2013, 135, 10258. [8] G. Occhipinti, V. Koudriavtsev, K. W. Törnroos, V. R. Jensen Dalton Trans., 2014, 43, 11106.

Theory-assisted design of Z-selective olefin metathesis catalysts

249th National Meeting (2015)

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