Hydrogenation Ruthenium

Figure 6.3 Racemization of a secondary alcohol in the presence of a ruthenium hydrogen-transfer catalyst.

Figure 6. Immobilization of Chiral Ruthenium Hydrogenation Catalyst in a Thin Hydrophilic Film on a Porous Glass Support...

The choice of the metals is strictly related to the catalytic application. As we shall show later, the catal54ic reaction most commonly investigated with polymer supported M / CFP catalysts is hydrogenation (Table 3). The overwhelming majority of catalytic studies concerns the hydrogenation of alkenes and by far the most commonly employed metal is palladium, followed by platinum. Examples of rhodium and ruthenium hydrogenation catalysts supported on pol5uneric supports are very rare. 

Figure 4.16. BINAP-Ruthenium hydrogenations of functionalised ketones...

Jack Halpern Perhaps I have more reason than anyone else to be disposed to the view that 7r-complexing is an important step of the insertion reaction, because I think that possibly we have the only reasonably clear cut case of an olefin insertion reaction where a complex is clearly implicated. This is the ruthenium chloride-catalyzed hydrogenation of certain olefins, which almost certainly involves the insertion of the olefin into a ruthenium hydrogen bond and where certainly a ruthenium olefin complex is involved as an observable reactant. Nevertheless, I am not at all sure to what extent this is a general or necessary feature of such insertion reactions. The important question is whether one or two coordination positions on the metal ion are involved in the transition state of the insertion reaction. For example, if one considers the insertion of an olefin, say into an M—X bond, then the transition state may look something like ... 

Preliminary interpretation of the ir spectra for Eu2RuHe and Yb2RuH6 suggested that there were absorptions that could be assigned to the ruthenium-hydrogen stretching and bending vibrations. The results of the ir data are found in Table VI. 

Allylic alcohols (Continued) ruthenium hydrogenation, 39 titanium epoxidation, 10, 139, 141, 289, 310, 361... 

The ruthenium hydrogenation catalyst RuH HB(pz)3KPPh3)2 is readily proton-ated to give a dihydrogen complex ... 

The preparation of Step 2 secondary and tertiary amines by reacting an aldehyde with a primary or secondary amine, respectively, in the presence of a a ruthenium hydrogenation catalyst is described (2). 

The N-tosyl derivative 5, a possible precursor for the synthesis of ruthenium hydrogen transfer catalysts of type 6, is obtained in good yield by slow addition of TsCl in dichloromethane at 0 °C (eq 4). 

Rapala and Parkas found that ruthenium hydrogenation of estrone, estradiol, and related steroids (1) gives rise to 3/3-hydroxy-5o ,IOa-estranes (2) as the major... 

Ruthenium hydrogenation catalyst. A 5% ruthenium-carbon (Norit) catalyst and a 5% Ru-AljO , catalyst are supplied by Engelhard Industries. Some investigators employ ruthenium dioxide, which is reduced to the metal in situ. 

Rapala and Farkas" found an entry into another series of 19-norsteroids in ruthenium hydrogenation of 19-nortestosterone (3), followed by oxidation with N-bromoacetamide to give 5/3,10/3-estrane-3,17-dione (4) as the major product. 

Freifelder and Stone" found that phenylalkylamines can be reduced to cyclo-hexylalkylamines in excellent yield by ruthenium hydrogenation. Under similar conditions, pyridines are reduced efficiently to the corresponding piperidines."... 

Ruthenium hydrogenation of estrone, estradiol, or related steroids 7 gives 3 )3-hydroxy-5 a,10 a-estranes 8 as the major products [equation (e)]. Reaction proceeds through a 3-keto intermediate and the stereochemistry of the product at all three new asymmetric centers follows the pattern of cfr-rear attack. ... 

Other experiments on nitrogen fixation have used transition metai compiexes of nitrogen.74 One used a tungsten nitrogen compiex with a ruthenium hydrogen complex at 55°C to produce a 55% yield (based on tungsten) of ammonia.75 Intermetallic compounds of iron and titanium have been used with ruthenium on alumina to make some... 

A further interesting contrast between rhodium and ruthenium hydrogenation catalysts in kinetic resolution is provided. Most of the published work for the latter relates to ruthenium (BINAP) chemistry but a wider spectrum of allylic alcohols is reduced with satisfactory selectivity the need for an electron-withdrawing group at the a -position is no longer evident. Where a direct comparison can be drawn between rhodium(BINAP) and ruthenium(BlNAP) (Table 6, entry 1), the reduction with a given enantiomer of catalyst gives the opposite enantiomer of a... 

---