Ru PPh

Shortly after Footes initial report on cobalt catalyzed reactions (see Sect. 5.8), Noyori and coworkers found that Ru(PPh)3Cl2 catalyzes the reductive cleavage of endoperoxides (Fig. 47) [152, 259]. While 1,2-dioxanes provided a mixture of... 

Octahedral Ru, PPhs groups trans, CO groups cis. Ru—N 2.086 A Ru bound to B3C2 of carbaborane and pseudo 7-co-ordinate D3. Mean Ru—S 2.383 A S—Ru—S bite angle 73.1°... 

The heterocyclic biphosphine (62) and the phosphorane (63) can be obtained, respectively, by treatment of bistrifluoromethylphosphine with dimethylzinc and from reactions between petfluorobut-2-yne and the hydride Ru(PPhs)3(77-C5Hs)H or Au(PPh,)Me (see pp. 309 and 347). 

For the achiral Ru(Cl)2(PPhj)j system, Backvall and co-workers have concluded that the active catalyst is the dihydride, Ru(PPh)3(H>2. The latter is formed from Ru(Cl)2(PPh3)3 in isopropanol with added base and was identified by P NMR. The dihydride gave immediate reaction between cyclopentanol and acetone in the presence of K2CO3, while Ru(CI)2(PPh3)3 and Ru(H)(Cl)(PHi3)3 were slower to react and show induction periods. 

However, if the H and D in the dihydride are chemically equivalent or become scrambled, then the racemate will have 50% of the D on the a-carbon. In practice, the deuterium content of the product is always somewhat less than predicted. For the Ru(PPh>3(H)2 catalyst described in the previous paragraph, 37% of the expected D was found on the a-carbon. Pkmies and Backvall applied this method to a number of catalysts and found that many Rh and Ir catalysts gave >90% retention of D on the a-carbon, suggesting a monohydride pathway. The same was true for most of the Ru systems tested, except for the case mentioned above and for (Ph3p)2Ru(Cl)2(Ti2-NH2CH2CH2l ). 

Treatment of mer,frans-[iPNP)Ru PPhs)C 2 with HG=GR (R = Ph, -tolyl) affords the vinylidene complexes /77T,m-[(PNP)Ru =G=GH(R) Gl2] in refluxing THF, but the alternative ds,mer-isomcr in refluxing THF/EtOH. Subsequent addition of LiG=GPh converts the fac,ds-spccics into the alkynyl enynyl complex... 

---