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

Ene-yne Cross-Metathesis for the Preparation of 2,3-Diaryl-1,3-dienes

“…A similar beneficial effect of increasing ethylene pressure from 1 to 6 atm had been observed during the ene-yne cross-metathesis of ethylene with terminal propargylic acetates [47]. These results indicated that the ene-yne metathesis of 1,2-diphenylacetylene required higher pressure than the ene-yne metathesis of the terminal phenylacetylene, which was carried out in short reaction time under 1 atm of C 2 H 4 at 80 • C in toluene with catalyst I [26,[53][54][55], and even at room temperature with a bimetallic ruthenium metathesis catalyst precursor [56]. The Hoveyda catalyst II was then evaluated under various experimental conditions.…”

“…It was literature. A few mono-substituted 2-arylbuta-1,3-dienes have been obtained from terminal arylacetylenes [25,26,[53][54][55][56], but to the best of our knowledge only one example of synthesis of 2,3-diphenylbuta-1,3-diene via ene-yne cross-metathesis starting from an internal alkyne has been reported [57]. Herein, we report on the application of ruthenium-catalyzed ene-yne cross-metathesis for the direct preparation of 2,3-diarylbuta-1,3-dienes of type A from ethylene and a variety of internal alkynes.…”

“…However, if many examples involving ruthenium-catalysis have been described starting from aliphatic including benzylic and propargylic alkynes [49][50][51][52], much less data are available from aromatic alkynes in the literature. A few mono-substituted 2-arylbuta-1,3-dienes have been obtained from terminal arylacetylenes [25,26,[53][54][55][56], but to the best of our knowledge only one example of synthesis of 2,3-diphenylbuta-1,3-diene via ene-yne cross-metathesis starting from an internal alkyne has been reported [57].…”

Ni‐Catalyzed Regioselective Cyclotrimerization of Internal Esteryl Alkynes towards Polysubstituted Benzene Rings

“…Cyclotrimerization of alkynes is an effective method for the construction of polysubstituted benzene derivatives and an important cornerstone for the synthesis of new materials and bioactive compounds with high atomic economy [1–10] . Since the first proposal by Schweckendiek and Reppe for transition metal‐catalyzed trimerization of alkynes in 1948, [11] a variety of polysubstituted benzene derivatives have been achieved in the presence of Ru, [12–16] Rh, [17–22] or Pd [23–27] catalysts, among others [28–35] . Generally, the investigation is dominated by the transformation of terminal alkynes, [36–39] and the control of regioselectivity is still a bottleneck.…”

Recent Advances in Ruthenium(II)‐Catalyzed C−H Bond Activation and Alkyne Annulation Reactions

“…Karabulut and co‐workers have found that the Ru(II)‐catalyzed cyclotrimerization reaction of phenylacetylene could be converted to an enyne metathesis reaction by the use of NHC ligands [IPr, 1,3‐bis(2,6 diisopropylphenyl)imidazol‐2‐ylidene] under an ethylene atmosphere (Scheme ) …”