Biomedical Engineering Reference
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R
OH
O
Ar
Ar
X
R
R = alkyl, aryl; Ar = aryl; X = I, Br
Me
Me
O
O
Me
Me
OTBS
I
O
CuCl,
L13
Cs
2
CO
3
Py, reflux
92%
O
O
steps
O
OTBS
O
O
Me
O
Me
OH
85
86
Me
87
Me
OH
OH
O
Intermolecular
cross-coupling
CuO, K
2
CO
3
Py, 130°C
(55%)
OH
HO
O
O
OH
O
OH
OH
O
O
and
O
O
O
O
Me
Me
Me
Me
Me
Me
Aspercyclide A
Aspercyclide B
Aspercyclide C
OH
CuI,
L6
Cs
2
CO
3
PhMe
110°C
O
HO
88
230°C
OTBS
OTBS
I
91
OTBS
90
Claisen rearrangement
13 steps
89
MeO
MeHN
O
NH
NH
O
Me
NH
Me
Me
O
Me
Abyssenine A
SCHEME 3.33
Cu-Assisted arylation of phenols and alcohols: syntheses of aspercyclides
and abyssenine A.
3.3.6. C-O Bond Formation
3.3.6.1. Intermolecular Arylation Owing to its catalytic usefulness for the
C-N bond formation, it is not surprising that copper salts have also been used for
preparing diaryl ether motifs that are present in many natural products. Indeed,
copper-mediated arylation of phenols and alcohols are commonly used for
constructing such subunits. Two examples are given in Scheme 3.33.
F
urstner and coworkers described an elegant approach to aspercyclides
A-C [84]. Intermolecular diaryl ether cross-coupling has been used for building
the diaryl moiety part of the 11-membered diaryl ether core of such compounds.
These reactions are sensitive to steric hindrance as illustrated in the synthesis of
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