New [Ru₃(CO)₁₂]‐Based Catalysts with Imidazolinium Salt, Diimine, or Bis(oxazoline) Ligands and Ruthenium Bis(oxazoline) Complex for Tandem Isomerisation/Claisen Rearrangement of Dienyl Ethers − X‐ray Structure of [RuCl{(R,R)‐bis(isopropyloxazoline)}(p‐cymene)]BF₄

Abstract

The reaction of various 1,7‐dienes in the presence of the three‐component catalyst A: [Ru3(CO)12]/imidazolinium salt/Cs2CO3 (1:1:2) leads to the tandem alkene isomerisation/Claisen rearrangement affording γ,δ‐unsaturated aldehydes. Other three component catalysts: [Ru3(CO)12]/diimine/Cs2CO3 and [Ru3(CO)12]/benzoxazoline or chiral bis(oxazoline)/Cs2CO3 offer new active catalytic systems for these tandem reactions. Two ruthenium complexes containing optically active bis(oxazoline), [RuCl{(R,R)‐bis(oxazoline)}(p‐cymene)]BF4, were prepared and the X‐ray structure of one of them (18) was established. The combination of chiral 18/imidazolinium salt/Cs2CO3 (1:1:2) catalysed the above reaction of 1,6‐dienes and the results suggest initial catalytic isomerisation followed by a thermal Claisen rearrangement. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Homologation of Monoterpenoids into New Sesquiterpenoids via Tandem Isomerisation/Claisen Rearrangement Reactions with Three‐Component Ruthenium Catalysts, and Ru(methallyl)2(COD) Revealed by High Throughput Screening Techniques

“…Starting from these observations, variations on the catalytic system and especially the use of bidentate ligands such as bisbenzoxazole, [16] chiral bisoxazoline and diimine, [17] associated with a ruthenium source, have shown isomerisation capability. The most efficient catalytic system B was then evaluated for terpenoids.…”

Heteroleptic ruthenium(II) complexes of 2-(2-pyridyl)benzimidazoles: A study of catalytic efficiency towards transfer hydrogenation of acetophenone

“…molecule B] are smaller than the ideal tetrahedral angle (109.47°), which is counterbalanced by the extending of the XRu-L (L is Cl1, N1 or N3) angles [mean 130.7(2)°for molecule A and 130.6(2)°for molecule B].Similar to related Ru(II)-arene complexes[33][34][35][36][37][38][39][40][41], there are substantial differences in the C-C [1.352(15)-1.460(14) Å for molecule A and 1.380(15)-1.424(15) Å for molecule B] and Ru-C [2.137(10)-2.231(10) Å for molecule A and 2.151(10)-2.214(12) Å for molecule B] distances for the arene ring. In the complex, the arene ring is planar with an r.m.s deviation from the plane being 0.0152 Å [0.0094Å].…”

“…Many Ru(II)-arene complexes having the same coordination environment have been reported crystallographically [33][34][35][36][37][38][39][40][41]. According to the bond lengths in these structures, the Ru-X, Ru-C, Ru-Cl and Ru-N bond lengths vary from 1.674 to 1.704 Å, from 2.141 to 2.273 Å, from 2.385 to 2.432 Å and from 2.077 to 2.130 Å, respectively.…”

Scope and advances in the catalytic propargylic substitution reaction

“…Dixneuf and co-workers in 2005 have earlier demonstrated the role of bisoxazoline-ruthenium complex precursors in the direct propargylation of weak nucleophiles with propargyl alcohols 141 Thereaer the same group reported that a mononuclear (bisoxazoline)(arene)ruthenium(II) complex catalyses the direct propargylation of furan 230 by propargyl alcohols 229 with C-C bond formation in moderate yields, Scheme 102. 142 Although the yields were modest the scope to modify the bisoxazolidine ligand by steric and electronic modications to provide higher catalytic activity and play a crucial role in enantioselective catalysis was encouraging.…”

“…Dixneuf and co-workers in 2005 have earlier demonstrated the role of bisoxazoline–ruthenium complex precursors in the direct propargylation of weak nucleophiles with propargyl alcohols 141 Thereafter the same group reported that a mononuclear (bisoxazoline)(arene)ruthenium( ii ) complex catalyses the direct propargylation of furan 230 by propargyl alcohols 229 with C–C bond formation in moderate yields, Scheme 102 . 142 …”