548791-91-9Relevant academic research and scientific papers
Reactions of ruthenium benzylidene complexes with cyclic and acyclic imines: Oligomerization of 1-pyrroline and metathesis via tautomerism
Zhang, Jubo,Gunnoe, T. Brent
, p. 2291 - 2297 (2003)
At room temperature, NMR spectroscopy indicates that the ruthenium benzylidene complex (Cl)2(PCy3)2Ru=CHPh reacts with 1-pyrroline to yield (Cl)2(PCy3)(1-pyrroline)Ru=CHPh. Heating a solution of (Cl)2(PCy3)2Ru=CHPh with excess 1-pyrroline to 90°C results in ring-opening oligomerization of the cyclic imine. The combination of ruthenium carbene complexes (Cl)2(PCy3)2Ru=CHPh and (Cl)2(PCy3)(H2IMes)Ru=CHPh (H2IMes = 1,3-dimesityl-4,5-dihydroimidazolylidene) with acyclic imines of the type (R)N=CH(R′) results in metathesis reactions when the imine possesses a C-H bond α to the imine carbon. Imines that lack C-H bonds α to the imine carbon do not react with (Cl)2(PCy3)2Ru=CHPh. The primary products from the reactions of (Cl)2(PCy3)2Ru=CHPh and (Cl)2(PCy3)(H2IMes)Ru=CHPh with acyclic imines are olefins and new Fischer carbene complexes of the type (Cl)2(L)(L′)Ru=CH{N(H)R} (L = L′ = PCy3; L = PCy3 L′ = H2IMes). The ruthenium complex (Cl)2(PCy3)2Ru=CH{N(H)Pr} has been isolated from the reaction of (Cl)2(PCy3)2 Ru=CHPh with (Pr)N=CH(i-Pr) and has been fully characterized. A possible pathway for the reactions of (Cl)2(PCy3)2Ru=CHPh and (Cl)2(PCy3)(H2IMes)Ru=CHPh with acyclic imines that involves imine to enamine tautomerism followed by C=C bond metathesis reactions is discussed. The failure of the ruthenium benzylidene complexes (Cl)2(PCy3)2Ru=CHPh and (Cl)2- (PCy3)(H2IMes)Ru=CHPh to react with the C=N bonds of a cyclic imines in combination with observed reactivity between Ru(Cl)2(PPh3)3 and 1-pyrroline indicates that the oligomerization of 1-pyrroline with (Cl)2(PCy3)2Ru=CHPh likely proceeds via a Lewis acid catalyzed mechanism.
