137
A similar oxidative radical cross-coupling for the construction of acyloxy ethers
from cyclic ethers and carboxylic acids can be also achieved (Scheme 4.58) [42]. In
this transformation, Fe(acac) 3 or Cu(OAc) 2 is used as the catalyst with TBHP or
DTBP as the oxidant under atmospheric conditions.
R-COOH +
10 mol% CuO
4 equiv DTBP
20 mol% K 2 CO 3
120°C, 24 h
O
R
O
O
O
74%
O
O
59%
O
O
O
O
84%
t BuOH
[O]
t BuOH
R
CO 2 H
Cu
III (OtBu)
R
O
O
Cu
III
(Ot Bu)
R
O
O
Scheme 4.57 Oxidative coupling of alkanes and carboxylic acids
R-COOH +
O
O
Cu(acac) 2
TBHP
120°C, 12 h
O
O
O
R
O
R-COOH +
O
O
Fe(acac) 3
DTBP
120°C, 24 h
O
O
O
R
O
Scheme 4.58 Oxidative coupling of cyclic ethers and carboxylic acids
4 Oxidative Radical Couplings