Chemistry Reference
In-Depth Information
Me
Me
Me
Me
Me
CO
2
Me
OTf
151
OMe
MeO
OMe
MeO
O
Me
O
Me
BEMP (
10
)
O
CO
2
Me
OH
MeO
2
C
O
HO
150
152
CH
2
Cl
2
, 95%
2.
1. Me
2
AlCl
MeO(Me)NH,HCl
72%
MeO
MgBr
90%
MeO
Me
Me
B
-
H
4
N
+
Me
3
MeO
MeO
O
Me
MeO
O
76% (dr 5.5 : 1)
O
153
Me
Me
OMe
OMe
MeO
MeO
O
Me
Me
O
OMe
MeO
O
OH
OH
manassantin A (
154
)
Scheme 7.34
Synthesis of manassantin A (154)
TBSO
N
HBz
O
TBSO
Me
Me
Me
Ph
O
Me
Ph
O
Ph
O
OH
Me
Me
Me
OAc
Me
DBU (
1
)
O
OAc
O
B
HO
H
H
Me
HO
O
OAc
HO
toluene, reflux
86%
O
BzO
Me
O
B
HO
Me
O
C
H
D
AcO
O
OMe
Cl
O
Me
OH
OMe
C
D
Me
Me
Me
Me
O
155
156
taxol (
157
)
Scheme 7.35
Synthesis of taxol (157)
7.7
Isomerization
Baros et al. reported a quantitative isomerization of exo-olefin 189 to the thermodynami-
cally stable
-unsaturated ketone 190 in the presence a catalytic amount of DBN at room
temperature in quantitative yield [57]. The two TBS groups were smoothly deprotected to
give (
a
,
b
)-eutypoxide B (191) (Scheme 7.43).
