Insights into the Decomposition of Olefin Metathesis Precatalysts

Abstract

The decomposition of a series of benzylidene, methylidene, and 3-phenylindenylidene complexes has been probed in alcohol solution in the presence of base. Tricyclohexylphosphane-containing precatalysts are shown to yield [RuCl(H)(H 2 )(PCy 3 ) 2 ] in isopropyl alcohol solutions, while 3phenylindenylidene complexes lead to h 5 -(3-phenyl)indenyl products. The potential-energy surfaces for the formation of the latter species have been probed using density functional theory studies. AngewandteChemie 9141

Ruthenium‐Catalyzed Regioselective 1,2‐Hydrosilylation of N‐Heteroarenes

“…This result indicates that the silane is required for catalyst activation. In the absence of quinoline, [RuCl(PPh 3 ) 2 (η 5 ‐(3‐phenylindenylidene))] reacts with primary silane to give the ruthenium hydride [Ru(PPh 3 ) 2 H(3‐phenylindenylidene)] 4 [23] after a short induction period, displaying a triplet at δ −14.3 (t, J =31.2 Hz) ppm in the 1 H NMR spectrum. The concentration of compound 4 increased with time, reaching complete conversion after 6 h (Scheme 3, B and Supporting Information).…”

Cyclic (Alkyl)(amino)carbenes (CAACs) in Ruthenium Olefin Metathesis

“…This Revised manuscript arguably impedes their catalytic activity under mild conditions, because of catalyst degradation. 64,65 To circumvent these limitations, Fogg and coworkers reported a novel (CAAC)Ru-indenylidene dimer Ru-62, 66 bridged by dative Cl interactions. 67 To access this species, the bis(CAAC)Ru indenylidene Ru-43 was treated with CuCl in the absence of additional donors in CH2Cl2 (Scheme 15).…”

Regio, stereo and chemoselectivity of 2nd generation Grubbs ruthenium-catalyzed olefin metathesis

“…However, trying to correlate all these details into a single picture is complicated as the catalysts, the experimental conditions, or the computational approach, change from one work to the other, [40] apart from any decomposition that those olefin metatheses potentially suffer. [41,42,43,44,45,46,47] Nevertheless, some general trends are by now well established. In terms of reactivity/yields/turnover number (TON), fundamental studies (investigating metathesis events per unit of time) evidenced that the intrinsic capability of 2 nd -generation N-heterocyclic (NHC) catalysts [48,49,50] is masked by the occurrence of non-productive (or degenerate) metathesis (Scheme 1).…”