Ruthenium-Catalyzed Allylic Substitution of Cyclic Allyl Carbonates with Nucleophiles. Stereoselectivity and Scope of the Reaction

CpRuCl(cod)/NH₄PF₆ (Cp = cyclopentadienyl, cod = 1,5-cyclooctadiene) is an effective catalyst system for the allylic substitution of cyclic allyl carbonates with nucleophiles. This catalyst system enables the first investigation of the stereochemical course of the ruthenium-catalyzed allylic substitution reaction, in which the reaction proceeds with an overall retention of configuration. The stoichiometric reaction of trans-5-(methoxycarbonyl)cyclohex-2-enyl chloride with Cp*RuCl(cod) (Cp* = pentamethylcyclopentadienyl) gave the unexpected complex Cp*Ru(η⁶-C₆H₅CO₂Me)⁺ by the rapid dehydrohalogenation/dehydrogenation of the desired Cp*RuCl₂(η³-C₆H₈CO₂Me) complex.