A ruthenium-based catalytic system with switchable selectivity between cyclotrimerization and enyne metathesis/Diels–Alder reactions of terminal alkynes

AbstractIn this study, we report a practical catalytic system, [RuCl2(p-cymene)]2/IPr (IPr: 1,3-bis(2,6 diisopropylphenyl)imidazol-2-ylidene), that can switch between cyclotrimerization and cross enyne metathesis. The cyclotrimerization reaction of phenylacetylene catalyzed by [RuCl2(p-cymene)]2 can be switched to enyne metathesis by the introduction of a sterically hindered N-heterocyclic carbene. The 1,3-diene formed during this reaction reacts with dienophiles to form the Diels–Alder adduct. A practical one-pot synthesis method, utilizing enyne metathesis/Diels–Alder reactions, was used to construct cyclic compounds in an efficient manner