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O
+
N
R
1
Rh
2
(OAc)
4
O
SO
2
Ph
N
R
1
-
O
SO
2
Ph
+
N
O
N
58
-
57
R
2
R
2
R
2
-PhSO
2
H
O
N
N
RO
PhO
2
S
R
1
R
1
O
O
60
(R = H)
61
(R = Tf)
59
steps
R
2
OH
Me
N
N
N
N
H
HO
2
C
Ar
CO
2
H
O
O
-Carbolinone core
64
Ace Inhibitor A58365A
62
Ipalbidine
63
(Ar =
p
-HOC
6
H
4
)
β
SCHEME 13.13
isomunchnone dipole derived from diazo sulfone
57
with methyl acrylate
(Scheme 13.14) [28]. This multistep sequence proceeded smoothly and in high yield
when catalyzed by rhodium(II) acetate. Hot aqueous hydrobromic acid then effected
decarbomethoxylation of
65a
to give
65b
in 82% yield. Etherification of
65b
with
commercially available (
E
)-1-bromo-2-pentene and cesium carbonate in dimethyl-
formamide produced the expected substitution product
65c
, which underwent a
O
O
O
OR
1
OH
Rh(II)
Methyl
acrylate
heat
N
N
N
SO
2
Ph
O
+
R
2
N
C
2
H
5
-
65a
(R
1
= H; R
2
= CO
2
Me)
65b
(R
1
= R
2
= H)
65c
(R
1
= CH
2
=CHC
2
H
5
; R
2
= H)
57
N
66
PhNTf
2
(CH
3
)
4
Sn, Pd(0)
O
O
O
CH
3
CH
3
O
3
o
-Amino
PhCHO
CH
3
N
RhCl
3
N
N
[O]
CH
3
N
X
C
2
H
5
X
C
2
H
5
69
(X = CHCH
3
)
70
(X= O; mappicine ketone, 60%)
68a
(X = H,H)
68b
(X = O, 62%)
67
SCHEME 13.14
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