Ruthenium dioxoruthenium complex

Although the chiral ketoiminatomanganese(lll) complexes were reported to catalyze the asymmetric aerobic alkene epoxidations, an aldehyde such as pivalaldehyde is required as a sacrihcial reducing agent. Groves reported that the dioxo(porphyrinato)ruthenium complexes 31, prepared with m-chloroperoxyben-zoic acid, catalyzed the aerobic epoxidation without any reductant. " On the basis of these reports, Che synthesized the optically active D4-porphyrin 35 and applied it to the truly aerobic enantioselective epoxidation of alkenes catalyzed by the chiral frani-dioxo (D4-porphyrinato)ruthenium(Vl) complex. The dioxoruthenium complex catalyzed the enantioselective aerobic epoxidation of alkenes with moderate to good enantiomeric excess without any reductant. In the toluene solvent, the turnovers for the epoxidation of T-(3-methylstyrene reached 20 and the ee of the epoxide was increased to 73% ee. 

Zeolite-encapsulated perfluorinated ruthenium phthalocyanines catalyze the oxidation of cyclohexane with t-BuOOH [146]. A dioxoruthenium complex with a D4-chiral porphyrin ligand has been used for the enantioselective hydroxylation of ethylbenzene to give a-phenylethyl alcohol with 72% e.e. [147]. 

X-ray data obtained for a closely related Ru(VI)(TDCPP)(0)2, definitively established a structural precedent for the /rans-dioxoRu(VI) porphyrin complexes . The structure revealed a nearly planar arrangement of the porphyrin macrocycle and two relatively long Ru=0 bonds of 1.729 A (Figure 1.18). Marchon and coworkers have published an X-ray structure of /r /w-dihydroxoruthe-nium(rv) complex of H2TDCPP , also obtained from the reaction of Ru(II)(TDCPP)(CO) with m-CPBA. The IR spectrum of the Irans-dihydroxo-ruthenium(IV) complex was reported to be different from that of the Pv3i s-dioxoruthenium(VI) complex. Thus, Ru(IV)(TDCPP)(OH)2 showed a Ru-O stretch at 760 cm in the IR spectrum... 

---