138
Oxidative C-O coupling between phenols and olefins can be realized using
FeCl 3 as the catalyst and 2,3-dichloro-5,6- dicyano-1,4-benzoqinone (DDQ) as the
oxidant at room temperature (Scheme 4.59) [43]. And highly selective oxidative
cross- coupling/cyclization affords the dihydrobenzofuran compounds in good to
excellent yields.
To confirm this iron-catalyzed oxidative cross-coupling/cyclization undergoes
radical process, a radical-trapping experiment is conducted. In the presence of one
equiv. of TEMPO, no target product is obtained under the standard conditions,
R
OH
+
10 mol% FeCl 3
DDQ, RT
toluene
Ar
R
O
Ar
MeO
O
86%
MeO
O
Cl
50%
MeO
O
Ph
Ph
79%
MeO
O Ph
87%
Br
O Ph
62%
MeO
O
tBu
86%
MeO
O
77%
R
OH
R
O
FeCl 3
R
O FeCl 3
Ar
FeCl 3
R
O
Ar
H
R
O
Ar
DDQ
HDDQ
HDDQH
B
C
A
Scheme 4.59 Oxidative C-O coupling between phenols and olefins
W. Liu
Oxidative C-O coupling between phenols and olefins can be realized using
FeCl 3 as the catalyst and 2,3-dichloro-5,6- dicyano-1,4-benzoqinone (DDQ) as the
oxidant at room temperature (Scheme 4.59) [43]. And highly selective oxidative
cross- coupling/cyclization affords the dihydrobenzofuran compounds in good to
excellent yields.
To confirm this iron-catalyzed oxidative cross-coupling/cyclization undergoes
radical process, a radical-trapping experiment is conducted. In the presence of one
equiv. of TEMPO, no target product is obtained under the standard conditions,
R
OH
+
10 mol% FeCl 3
DDQ, RT
toluene
Ar
R
O
Ar
MeO
O
86%
MeO
O
Cl
50%
MeO
O
Ph
Ph
79%
MeO
O Ph
87%
Br
O Ph
62%
MeO
O
tBu
86%
MeO
O
77%
R
OH
R
O
FeCl 3
R
O FeCl 3
Ar
FeCl 3
R
O
Ar
H
R
O
Ar
DDQ
HDDQ
HDDQH
B
C
A
Scheme 4.59 Oxidative C-O coupling between phenols and olefins
W. Liu