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O
O
Me
Me
AgF
TMS
O
O
N
OBz
O
N
OBz
O
+
TMS
292
293
56%
O
H
Me
steps
O
O
OBz
O
O
N
H
N
H
295
294
OH
O
OH
O
N
H
(-)-Pancracine
SCHEME 13.55
enone to provide
294
in 56% yield (Scheme 13.55). Standard functional group
interconversion, including ring closure, provided advanced intermediate
295
. Over-
man and coworkers had previously synthesized pancracine from compound
295
,
thereby resulting in a formal synthesis of this alkaloid.
SO
2
Et
LiEt
3
BH
PdCl
2
(dppp
)
H
2
N SnBu
3
190a
PhMe
85°C
56%
N
SO
2
Et
N
O
84%
O
O
I
O
O
O
O
296
297
298
S(O)Et
190a
PhMe
85°C
56%
N
O
O
I
O
O
O
299
300
HO
N
N
MeO
MeO
O
O
O
O
Homoerythratine
3-
epi
-Schelhammeridine
SCHEME 13.56
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