Biomedical Engineering Reference
In-Depth Information
O
[Au]
-[Au]
Propargyl
Claisen rearrangement
O
O
-[Au]
[Au]
CO
2
Me
CO
2
Me
O
O
OBn
OBn
HO
HO
14
[(Ph
3
PAu)
3
O]BF
4
8
OPMB
OBn
8
H
H
CH
2
Cl
2
, rt
80%
O
HO
O
HO
O
14
OPMB
OBn
MeO
2
C
MeO
2
C
O
O
O
O
OMe
238
239
O
OMe
steps
O
CO
2
Me
O
OH
O
O
14
Azadirachtin
240
8
H
O
O
HO
HO
OH
MeO
2
C
O
SCHEME 4.67
Synthesis of azadirachtin by Ley and coworkers.
[Au]
O
[A
u
]
HO
OH
[Au]
-[Au]
Meyer-Schuster
rearrangement
R
2
R
1
R
2
R
1
R
1
R
2
[Au]
O
AcO
[A
u
]
-[Au]
OAc
[Au]
3,3-Rearrangement/
hydration sequence
R
2
R
1
R
2
+ H
2
O
- AcOH
R
1
R
1
R
2
O
O
(Ph
3
P)AuNTf
2
(0.6 mol%)
t
-BuOH (5 equiv)
Butanone/H
2
O (90:1), rt, 36 h
241
(R = Ac)
(95%)
O
O
C
5
H
11
C
5
H
11
242
[{(IPr)Au}
2
(
-OH)]BF
4
(2 mol%)
MeOH/H
2
O (10:1), rt, 2 h
μ
(R = H)
(86%)
OR
TBSO
O
OTBS
241
243
(R = Ac)
242
(R = H)
Prostaglandins
O
HO
O
CO
2
H
CO
2
H
CO
2
H
C
5
H
11
OH
C
5
H
11
OH
PGE
2
C
5
H
11
OH
PGF
2
OH
OH
OH
PGE
1
SCHEME 4.68
Zanoni's and Nolan's approach to prostaglandins.
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