Novel Ruthenium(II)2 Carboxylates as Catalysts for Alkene Metathesis

Abstract

The reactions of [Ru-(=CHR)Cl2(PCy3)2] (1: R = Ph; 1a: R = -CH=CPh2) with silver salts of carboxylic acids afforded new dimeric complexes of the general formula [Ru2(=CHR)2-(R'CO2)2(mu-R'CO2)2(PCy3)2(mu-H2O)] (2: R = Ph, R' = CF3; 3: R = Ph, R' = C2F5; 4: R = -CH=CPh2, R' = CF3; 5: R = Ph, R' = C6F5; 6: R = -CH=CPh2, R' = C6F5; 7: R = -CH=CPh2, R'=CCl3) in good yields. With R' = CF3, C2F5 or CCl3 these complexes are active catalysts for metathesis of acyclic alkenes, including unsaturated fatty acid esters, as well as for ring closing metathesis. The reactivity of these complexes with bases and weak donor solvents has been studied and their half-life times in several media were determined.

Ruthenium‐Catalyzed Ring‐Closing Metathesis: Recent Advances, Limitations and Opportunities

“…(It may be noted, however, that protonolyis of the tertbutoxide ligands with HCl can be used to reinstall a chloride ligand, providing a "back-door" route to highly active C16). Higher activity is found for acetate [141,143,147] and sulfonate [143] derivatives. Both catalysts C44 and C45 have been employed at reduced catalyst loadings, offering welcome insight into their "true" activity.…”

“…Both catalysts C44 and C45 have been employed at reduced catalyst loadings, offering welcome insight into their "true" activity. Complex C44 proved only slightly less active than C1a in CM of methyl oleate and trans-4-decene, though significantly less so for RCM of DEDAM; catalyst activity was curbed in donor solvents such as THF [141,147] Fig. (8)) is limited by Principles (2) and (3) above.…”

Ruthenium aryloxide catalysts: Synthesis and applications in ring-closing metathesis

“…Earlier work examined of the chloride ligands of the Grubbs catalyst 1 with alkoxide [16], tris(pyrazolyl)borate [17], salicylaldiminato [18,19], iminopyrrolato [20], or carboxylate [21] ligands (Fig. 2).…”

“…These include the twodimensional geometry of the ligand, which minimizes steric congestion, and the absence of potentially chelating secondary donor sites, as found in the carboxylates [21]. A further major asset is the ease with which the aryloxide group can be modified to modulate steric, electronic, atropisomeric, and other properties.…”

Diastereocontrol in Olefin Metathesis: the Development of Z ‐Selective Ruthenium Catalysts

“…For example, catalysts with κ 1 ligands initiated very slowly (13), or were almost completely inactive (14). This result was in stark contrast to traditional, non-C-H-activated catalysts, which do not display such a significant effect [29][30][31][32]. On the opposite end of the spectrum, catalysts with large carboxylate ligands initiated relatively fast.…”