Arene ruthenium complexes with pyridyloxazolines: synthesis and applications as asymmetric catalysts for Diels–Alder reactions †

Davenport, Adam J.; Davies, David; Fawcett, John; Garratt, Shaun; Russell, David R.

doi:10.1039/b006530g

Cited by 73 publications

(64 citation statements)

References 43 publications

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“…[16] For instance, these systems have been used as catalysts for the hydrogenation of alkenes, [17] olefin metathesis, [18] Diels-Alder reactions, [19] and, most prominently, for hydrogen-transfer reduction of ketones [20] and imines; [21] the latter reaction has been brought to near perfection with high yields and high enantiopurity by application of ruthenium complexes such as [(η 6 -arene)Ru(NH 2 CHRCHRNTos)X]. [22] In a similar fashion, we envisaged that coordinative unsaturation together with the presence of amido-type nitrogen groups (Schemes 1, 2, 3, and 4) renders the Mo and Ru complexes 1-8 active in hydrogen transfer catalysis.…”

Section: Introductionmentioning

confidence: 99%

16‐Electron (Arene)ruthenium Complexes with Superbasic Bis(imidazolin‐2‐imine) Ligands and Their Use in Catalytic Transfer Hydrogenation

et al. 2009

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The ligands N,N′‐bis(1,3,4,5‐tetramethylimidazolin‐2‐ylidene)‐1,2‐ethanediamine (BLMe) and N,N′‐bis(1,3‐diisopropyl‐4,5‐dimethylimidazolin‐2‐ylidene)‐1,2‐ethanediamine(BLiPr) react with [(η5‐C5Me5)RuCl]4 to afford cationic 16‐electron half‐sandwich complexes [(η5‐C5Me5)Ru(BLR)]+ (R = Me, 3; R = iPr, 4), which resist coordination of the chloride counterion because of the strong electron‐donating ability of the diimine ligands. Upon reaction with [(η6‐C6H6)RuCl2]2 or [(η6‐C10H14)RuCl2]2, these ligands stabilize dicationic 16‐electron benzene and cymene complexes of the type [(η6‐C6H6)Ru(BLR)]2+ (R = Me, 5; R = iPr, 6) and [(η6‐C10H14)Ru(BLR)]2+ (R = Me, 7; R = iPr, 8). The X‐ray crystal structure of [5]Cl2 reveals the absence of any direct Ru–Cl interaction, whereas a long Ru–Cl bond, supported by two CH···Cl hydrogen bonds, is observed for [(6)Cl]Cl in the solid state. Treatment of the dichlorides of 6 and 8 with NaBF4 affords [6](BF4)2 and [8](BF4)2, which are composed of individual dications and tetrafluoroborate ions with no direct Ru–F interaction. All complexes catalyze the transfer hydrogenation of acetophenone in boiling 2‐propanol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Introductionmentioning

confidence: 99%

16‐Electron (Arene)ruthenium Complexes with Superbasic Bis(imidazolin‐2‐imine) Ligands and Their Use in Catalytic Transfer Hydrogenation

et al. 2009

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“…methyl-amino-oxazoline (8 and 9, respectively), were somewhat less active than the analogous primary amino-oxazoline 5 (entries 14 and 17 vs 8), and what is more significant, they did not induce asymmetry (entries [13][14][15][16][17]. Then a primary amine moiety and not a secondary amine function in the ligand appears essential for the enantioselectivity.…”

Section: Secondary Amino-oxazolines N-(p-tolylsulfonyl)-and N-mentioning

confidence: 93%

“…The solvents were purified by standard procedures and distilled under nitrogen. [26] 13 C, 100 MHz, standard SiMe 4 ) spectrometers, using CDCl 3 as solvent, unless stated otherwise. Chemical shifts were reported downfield from standards.…”

Section: Methodsmentioning

confidence: 99%

“…Complexes 10 and 11 were obtained as a mixture of two diastereomers, since the ruthenium chiral center formed upon coordination of optically pure oxazoline ligand: (S Ru ,R C )-+ (R Ru ,R C )-10 and (S Ru ,S C )-+ (R Ru ,S C )-11, as observed for analogous arene Ru complexes containing pyridino-oxazolines. [13] In solution, complex 12 shows at least three isomers, probably due to the N stereocenter. The complexes were fully characterized both in solid state and solution.…”

Section: Ruthenium Complexesmentioning

confidence: 99%

“…s, 1 H) ppm. 13 58 mmol), DMAP (6.6 mg, 5.3 × 10 -2 mmol), and SiClMe 3 (0.132 g, 1.22 mmol) were successively introduced in a Schlenk. The solids were dissolved in 50 mL of freshly distilled chloroform, and the resulting mixture was stirred for 24 h at room temperature.…”

Section: (+)-(4јs)-2-(4ј-isopropyl-3ј4ј-dihydrooxazol-2ј-yl)aniline mentioning

confidence: 99%

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Ruthenium Complexes Containing Chiral N‐Donor Ligands as Catalysts in Acetophenone Hydrogen Transfer – New Amino Effect on Enantioselectivity

et al. 2005

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New p-cymene ruthenium species containing chiral amino alcohols (1-3), primary (4-7) and secondary (8, 9) aminooxazolines, were tested as catalysts in the hydrogen transfer of acetophenone, using 2-propanol as the hydrogen source. A remarkable effect on the enantioselectivity, but also on the activity, was observed depending on the amino-type oxazoline, Ru/8 and Ru/9 being low active and nonselective catalytic systems, in contrast to their primary counterpart Ru/5. Complexes containing amino-oxazolines (10-12) were prepared and fully characterized, both in solution and in solid state. The X-ray structure was determined for (S Ru ,R C )-10.

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Dichloro(mesitylene)ruthenium Dimer

Carole

Colacot

2011

Encyclopedia of Reagents for Organic Synthesis

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Arene ruthenium complexes with pyridyloxazolines: synthesis and applications as asymmetric catalysts for Diels–Alder reactions †

Cited by 73 publications

References 43 publications

16‐Electron (Arene)ruthenium Complexes with Superbasic Bis(imidazolin‐2‐imine) Ligands and Their Use in Catalytic Transfer Hydrogenation

16‐Electron (Arene)ruthenium Complexes with Superbasic Bis(imidazolin‐2‐imine) Ligands and Their Use in Catalytic Transfer Hydrogenation

Ruthenium Complexes Containing Chiral N‐Donor Ligands as Catalysts in Acetophenone Hydrogen Transfer – New Amino Effect on Enantioselectivity

Dichloro(mesitylene)ruthenium Dimer

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