Rhodium, chloro tris catalyst

The hydrogenation of vinylnaphthalene 1 was performed by mixing solid chloro-tris(triphenylphosphine)rhodium catalyst (7.0 mg, 7.6 pmol) with solid 2-vinyl-naphthalene (350 mg, 2.27 mmol, substrate Rh=300 l), both fine powders. The mixture was placed, with a stirring bar, into a 22 mm diameter flat-bottomed glass finer in a 160-mL high-pressure vessel, which was then sealed and warmed to 33 °C in a water bath. The vessel was flushed and pressurized with H2 to 10 bar. This was considered the start of the reaction. Carbon dioxide was then added to a total pressure of 67 bar. After 30 min, the vessel was removed from the water bath and vented. The product mixture was dissolved in CDCI3 and characterized by H NMR spectroscopy. 

Similarly, intramolecular [4 4- 2] cycloaddition of unactivated dienynes is also catalyzed and dramatically accelerated by low-valent rhodium complexes, e.g., Wilkinson s catalyst [chloro-tris(triphenylphosphane)rhodium] and phosphite analogs, under mild conditions46. Thus, ( , )-l-(2-propynyloxy)-2,4-hexadiene (3, Z = O) and similar dienynes, with 5 mol% of chlorotris(tri-phenylphosphane)rhodium in 2,2,2-trifluoroethanol for 30 minutes at 55 C. give up to quantitative yield of the cycloadducts with excellent to complete diastereoselection. According to control... 

Previous work has shown that the electronic characteristics of the benzene substituent in triarylphosphine chlororhodium complexes have a marked influence on the rate of olefin hydrogenation catalyzed by these compounds. Thus, in the hydrogenation of cyclohexene using L3RhCl the rate decreased as L = tri-p-methoxyphenylphosphine > triphenylphosphine > tri-p-fluorophenylphosphine (14). In the hydrogenation of 1-hexene with catalysts prepared by treating dicyclooctene rhodium chloride with 2.2-2.5 equivalents of substituted triarylphosphines, the substituent effect on the rate was p-methoxy > p-methyl >> p-chloro (15). No mention could be found of any product stereochemistry studies using this type of catalyst. 

HYDROGENATION CATALYSTS Bis-(pyridine)dimethylformamidedichlororho-dium borohydride. Iron pentacarbonyl. Lindlar catalyst. Nickel boride. Palladium-on-calcium carbonate. Rhodium-on-alumina. Rhodium-on-carbon. Ruthenium trichloride hydrate. Triron dodecacar-bonyl. Tris(triphenylphosphine)chloro-... 

Diazopropenes bearing, for example, chloro substituents on the double bond can readily be purified by short-path distillation. Subsequent vinylcyclopropanations are carried out at low temperature using copper(II) catalysts such as bis(trifluoroacetonato)copper(II), copper(II) tri-fluorosulfonate and copper(II) trifluoroacetate in the presence of a 15-60-fold excess of the alkene. The dimer of rhodium(Il) acetate (0.1 mol%, tenfold excess of alkene), however, is generally more effective, leading to higher yields in this reaction (see Houben-Weyl, Vol. El9b, Table 100). 

Butynediol can be selectively hydrogenated to c s-2-butene-l,4-diol in trifluoroeth-anol at - 20°C or in benzene-CF3CH20H at 0°C with tris(triphenyl-phosphine)chloro-rhodium(I) , or with IrCl(CO)(PPh3)2 as catalyst in toluene-trifluoroethanol at 60°C under weak UV irradiation ... 

A new polymer-supported rhodium(i) catalyst has been obtained by chloro-methylation of polystyrene beads containing 1.8% cross-linking of divinyl-benzene, converting to the diphenylphosphine, and then equilibrating with tris(triphenylphosphine)chlororhodium(i) (Scheme 22). This catalyst reduced... 

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