Biomedical Engineering Reference
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OMe
OMe
PhMe
MeO
MeO
H
Me
+
N
H
CO
2
Et
84%
CHO
H
N
CO
2
Et
205
206
207
Me
OMe
OMe
MeO
MeO
H
H
CO
2
Et
CO
2
Me
N
N
H
H
208
(93%)
209
(99%)
OMe
OMe
Cl
MeO
O
MeO
OMe
1
.
100°C
O
OMe
N
206
2. H
2
O/MeOH
3. NaOH to pH = 1
4. NaBH
3
CN
3 Å MS
Xylene
180°C
CO
2
R
CHO
CH
2
N
Me
N
Me
N
N
H
H
210
40%
87%
213
211
(R = Et)
NaOH
100%
212
(R = H)
SCHEME 13.42
decarboxylated under conditions developed by Rapoport and coworkers to give
213
in
87% yield from
211
[78].
Led byWang, the Du Pont group also reported the synthesis of
-lycorane using
an intramolecular cycloaddition strategy [79]. Alkylation of commercially available
214
with 5-bromo-1-pentene gave
215
in 67% yield (Scheme 13.43). Reduction of
the nitrile group in
215
using DIBAl-H produced aldehyde
216
in 90% yield. A
subsequent condensation of
216
with
N
-benzyl glycine that was pretreated with
a
O
O
LiN(
i
-Pr)
2
CN
R
Br
O
O
HMPA
214
215
(R = CN)
DIBAl-H
67%
90%
216
(R = CHO)
Bn
CO
2
H
HMDS
PhMe
N
H
25%
1. HCO
2
H
Pd/C
MeOH
H
H
H
H
H
H
O
O
2. CH
2
O, H
+
N
N
O
O
Bn
40%
α
-Lycorane
217
SCHEME 13.43
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