Carbamato-benzylidene ruthenium chelates - Synthesis, structure and catalytic activity in olefin metathesis

New carbamato-kN-benzylidene ruthenium chelates were synthesized from the first [RuCl2(PCy3) 2(=CHPh)] and second [RuCl2(SIMes)(PCy3)(=CHPh)] generation Grubbs catalysts by metathetic exchange of benzylidene ligand for tert-butyl (2-vinylphenyl) carbamates bearing benzylidene ligand substituted in the position para to carbamato functionality with methyl or trifluoromethyl group. In all metathetical transformations tested, i. e. in ROMP of cycloocta-1,5-diene, RCM of diethyl diallylmalonate and diethyl 2-allyl-2-(2-methylallyl) malonate and cross-metathesis of allylbenzene with Z-1,4diacetoxybut- 2-ene, the complexes behave like latent catalysts. Complexes remain completely inactive until they are activated by the addition of ethereal solution of HCl. The presence of the electronwithdrawing group results in a slight increase in the catalytic activity of the activated form of the catalyst relative to a similar form of the unsubstituted complex or the least active complex carrying the electron donating group. (C) 2018 Elsevier B.V. All rights reserved.