Catalytic oxidations using ruthenium porphyrins - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 42

was initially used as a catalyst precursor in benzene containing “2-3 drops of
concentrated aqueous HCl or HBr” under Ar at 20-40°C, with molecular
sieves added to maintain anhydrous conditions 160 . Essentially complete
conversion of adamantane yielded adamantan-1-ol (up to 68%), adamantan-
1,3-diol (25%) and adamantan-2-one (1%), while methylcyclohexane was
oxidized to 1-methylcyclohexanol (77%) and methylcyclohexanones (6%);
ethylbenzene and cyclohexanol were converted in 88% yield to
acetophenone and cyclohexanone, respectively. The acids were essential,
and NMR data suggest that these convert the dioxo species into the known,
paramagnetic species (X = halide) 49,71 . The dihalo complexes, as
well as Ru(porp)CO complexes (porp = TMP, TDCPP, TPFPP, and even the
non-sterically hindered TPP) were also effective catalyst precursors 161,162 .
For example, the (or HBr) system effected
hydroxylation of adamantane to 1-adamantanol (76.2%) and adamantan-1,3-
diol (13%) with turnovers of depending on the

while )-decal-9,10-

diol (4.2%) at up to 64 turnovers . The TPP, TMP, and TDCPP
systems also effected oxidation of steroids, with retention of configuration
for those containing chiral centers; for example, in the
presence of Ru(TPP)CO gave the 25-hydroxy product (11%) (Fig. 19), while
Ru(TMP)CO and Ru(TDCPP)CO generated other alcohols as well 161 .

cis -decalin was converted to ( Z )-9-decalol (79.6%) and ( Z

-decalin
hydroxylation by the Ru(TPFPP)CO system, coupled with observation of
intermediates ( 18 - 20 ) by UV-vis, IR and ESR spectroscopies, led to the
mechanism outlined in Figure 20 162 . An observed induction time was
attributed to formation of ( 20 ), and this induction period could be reduced by
initial treatment of the precursor ( 17 ) with O-atom transfer occurs
from ( 21 ), a Ru(V)-oxo (or a Ru(IV)-oxo-porphyrin cation radical 160 , which
had been suggested much earlier 8,69 - see above), and its formation was

Analysis of product evolution during adamantane and cis