Ruthenium(III) Chloride

RuCl3

[10049-08-8]  · Cl3Ru  · Ruthenium(III) Chloride  · (MW 207.42) (hydrate)

[14898-67-0]

(Lewis acid;1 catalyst for alkyne functionalization4 and oxidation6a)

Physical Data: mp >500 °C for anhydrous material.

Solubility: a-RuCl3 (black lustrous crystals) insol alcohol, water; b-RuCl3 (dark-brown, fluffy crystals) sol alcohol.

Form Supplied in: available as anhydrous solid and hydrated solid.

Analysis of Reagent Purity: elemental analysis.

Lewis Acid.

Ruthenium trichloride can serve as a mild Lewis acid. Treatment of norbornene oxide with this reagent results in a hydrocarbon skeletal rearrangement (eq 1).1 Other ruthenium reagents such as Ruthenium(VIII) Oxide are ineffective at bringing about the desired transformation. Ruthenium trichloride, in the presence of alcohols, also catalyzes the formation of allylic ethers from allylic alcohols (eq 2).2 It is likely that this process occurs via an allylic carbonium ion since racemization ensues when enantiomerically pure allylic alcohols are employed. The Prins reaction is catalyzed by ruthenium trichloride (eq 3).3 While it is possible that this reaction is proceeding in a fashion analogous to the Wacker oxidation, simple Lewis acid activity can explain the observed products.

Alkyne Functionalization.

Ruthenium trichloride catalyzes the reaction of Acetylene with Carbon Dioxide and secondary amines, providing vinyl carbamates in low to moderate yields (eq 4).4 Primary amines do not participate in this reaction and ruthenium dodecacarbonyl fails to catalyze this process. In an analogous transformation, ruthenium trichloride catalyzes the addition of carboxylic acids to terminal alkynes (eq 5).5 Higher selectivities and increased yields are obtained when Tri-n-butylphosphine is added to the reaction mixture.

Oxidations.

Ruthenium trichloride catalyzes the oxidation of alcohols in the presence of stoichiometric N-Methylmorpholine N-Oxide (eq 6).6a A slight preference is noted for primary over secondary alcohols. Also, tertiary amines are oxidized to amine oxides in the presence of ruthenium trichloride and molecular Oxygen.7a

C-H Activation.

Furan and thiophene undergo an alkylation-coupling process when exposed to ruthenium trichloride, an alcoholic solvent, and elevated temperatures (eq 7).8


1. Tenaglia, A.; Terranova, E.; Waegell, B. TL 1991, 32, 1169.
2. Ito, S.; Matsumoto, M. SC 1982, 12, 807.
3. Thivolle-Cazat, J.; Tkatchenko, I. CC 1982, 1128.
4. Sasaki, Y.; Dixneuf, P. H. JOC 1987, 52, 314.
5. Mitsudo, T.; Hori, Y.; Yamakawa, Y.; Watanabe, Y. JOC 1987, 52, 2230.
6. (a) Sharpless, K. B.; Akashi, K.; Oshima, K. TL 1976, 2503. (b) Tanaka, M.; Kobayashi, T.; Sakakura, T. AG(E) 1984, 23, 518.
7. (a) Riley, D. P. CC 1983, 1530. (b) Tang, R.; Diamond, S. E.; Neary, N.; Mares, F. CC 1978, 562.
8. Jaouhari, R.; Guenot, P.; Dixneuf, P. H. CC 1986, 1255.

Jeffrey A. McKinney

Zeneca Pharmaceuticals, Wilmington, DE, USA



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