Ruthenium Metathesis Catalysts Containing Chelating Aryloxide Ligands

Olefin metathesis catalysts containing chelating aryloxide donors, RuXX‘(IMes)(py)(CHPh) (5, XX‘ = 3,5-dichloro-2-oxidobenzenesulfonate; 6, XX‘ = catecholate), are accessible in high yield by reaction of o-sulfonato aryloxide or catecholate salts, respectively, with RuCl2(IMes)(py)2(CHPh). Isomerization to π-bound aryloxides, as found with phenoxide ion or 2‘-(diphenylphosphino)-1,1‘-binaphthyl-2-olate, is suppressed by use of these smaller, more rigid, chelate rings. Preliminary investigations indicate that the catecholato derivative exhibits metathesis activity approaching that of the recently reported, highly active catalyst RuCl(OC6Br5)(IMes)(py)(CHPh).