Chemistry Reference
In-Depth Information
Ph
Ph
(3-8 mol%)
1-naphthol (4-12 mol%)
air
6
(
R
)
H
H
OH
OH
O
N
N
+
Fe
R
1
R
2
toluene, 50-60 ºC
R
1
R
2
R
1
R
2
O
Ph
O
d
n
4
r
4
n
g
|
1
Ph
(
R
)
OH
HO
2
6
HO
R
R = H conv. = 55%
98% ee,
OH
k
rel
= 41
n
R = OMe conv. = 60%
97% ee,
n = 1, conv. = 55%
67% ee,
k
rel
= 7
k
rel
= 19
conv. = 54%
ee = 73%,
R = NMe
2
conv. = 54%
96% ee,
k
rel
= 39
R = CN, conv. = 56%
92% ee,
n = 2, conv. = 53%
82% ee,
k
rel
= 16
k
rel
= 9
OH
n = 3, conv. = 57%
88% ee,
k
rel
= 20
k
rel
= 14
R = Cl, conv. = 56%
91% ee,
k
rel
= 19
conv. = 57%
ee = 86%,
R = CF
3
conv. = 53%
90% ee,
k
rel
= 27
k
rel
= 13
OH
OH
OH
.
conv. = 54%
ee = 90%,
k
rel
= 23
conv. = 62%
ee = 99%,
k
rel
= 20
conv. = 52%
ee = 94%,
k
rel
= 50
Scheme 9.11
Iron(salan)-catalyzed OKR of aromatic and aliphatic secondary alco-
hols under air.
ruthenium(NO)(salen) complexes are precatalysts and NO ligand dissoci-
ation by irradiation in situ generates a genuine ruthenium(salen) catalyst,
which catalyzes alcohol oxidation via SET from alcohol-bound ruthenium
complexes to dioxygen and subsequent hydrogen atom transfer (HAT) by the
resulting oxygen radical cation. It is noteworthy that the rate-determining
step (RDS) depends on the nature of apical ligand (X); when the apical ligand
is Cl, the RDS is the SET step, and when the apical ligand is OH, the RDS is
the HAT step (Scheme 9.14). However, the KIE for diol oxidation indicated
that a radical cation is generated not on the naphthol oxygen but on the
alcohol oxygen, due to the stabilization of the radical cation by hydrogen-
bond formation,
24
and the subsequent HAT from the radical cation is
brought about by a superoxide in an intermolecular manner (Scheme 9.14,
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