Biomedical Engineering Reference
In-Depth Information
Ph
xylene
reflux
Ph
Ph
H
Y
Y
t-
BuOK
Y
N
HN
N
+
MeO
2
C
H
H
MeO
2
C
X
MeO
2
C
304a
(X = I, Y = CH
2
)
304b
(X = Br, Y = NTs)
305a
(X = I, Y = CH
2
)
305b
(X = Br, Y = NTs)
306a
(Y = CH
2
; 51%)
306b
(Y = NTs; 86%)
O
O
OMe
Cbz
H
Cbz
NH
4
Cl
N
N
N
MeO
2
C
xylene
reflux
48%
HN
H
H
MeO
2
C
307
308
SCHEME 13.58
Banwell and coworkers examined an intramolecular dipolar cycloaddition
sequence to fashion the pyrrole core of the lamellarin alkaloids [105]. For example,
isoquinolinium salt
309
was heated with Et
3
N, and the resulting cycloadduct was
treated with DDQ to provide
310
in 92% yield (Scheme 13.59). Encouraged by this
result, a more functionalized system was designed for the synthesis of lamellarin K.
1. Et
3
N
O
O
O
2. DDQ
N
92%
N
O
-
Br
309
310
MeO
OMe
MeO
OMe
MeO
i-
PrO
O
i-
Pr
MeO
i-
PrO
O
i-
Pr
+
MeO
O
N
O
MeO
O
i-
PrO
N
I
-
O
i-
PrO
311
312
313
I
81%
i-
Pr
2
NEt
OMe
OMe
OMe
OMe
HO
i-
PrO
OH
O
i-
Pr
AlCl
3
MeO
MeO
O
O
96%
N
N
O
O
MeO
MeO
HO
i-
PrO
314
Lamellarin K
SCHEME 13.59
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