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Fe (9 equiv)
HCl 12M (11 equiv)
X
N
X
N
+
R'
OH
Δ
, 48 h
R
N
R'
R
NO
2
66
(X = CH)
67
(X = N)
68
(X = CH)
69
(X = N)
N
N
N
N
H
N
Cl
N
Ph
MeO
N
Me
68a
, 56%
68b
, 60%
68c
, 56%
68d
, 69%
N
N
N
N
N
N
N
Ph
N
H
69a
, 50%
69a
, 61%
69a
, 54%
Scheme 7.18
Iron-mediated multistep synthesis of N-heterocyclic structures.
iron-mediated
R'
R'
OH
O
aerobic oxidation
X
N
R
N
R'
iron-mediated
X
N
X
N
XVIII
H
nitro reduction
NH
3
+
R
NO
2
R
cyclization
XVII
66
(X = CH)
67
(X = N)
X
N
iron-mediated
X
N
H
oxidation
R
N
R'
R
N
R'
XIX
H
68
(X = CH)
69
(X = N)
Scheme 7.19 Proposed mechanism of the multistep synthesis of N-heterocyclic
structures.
PEG-PS resin and TEMPO and also the preadsorption of the CuCl-bpy
complex were essential for an ecient aerobic oxidation step. The two
PEG-PS catalysts were also easily separable and reusable.
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