Biomedical Engineering Reference
In-Depth Information
organocatalysi
s
+
R
R
O
O
Me
O
N
Catalyst:
Ph
O
Product:
Me
Et
Me
N
H
O
76
(
endo
)
89%, ee = 90%
endo
:
exo
= 25:1
·HClO
4
75
F
3
C
CF
3
CF
3
+
CHO
Me
N
H
Me
CHO
OTMS
CF
3
78
(
exo)
ee = 99%
79
(
endo
)
ee = 99%
77
73%,
exo
:
endo
= 72:28
SCHEME 6.15
Organocatalytic Diels-Alder reactions between dienes and alkenes.
adduct
, which
underwent a transition metal-catalyzed cyclization/fragmentation to provide dienal
92
89
was then converted to the corresponding propargyl alcohol
91
in 97% ee after recrystallization. A final Wittig olefination eventually led to
b
-santalol (
93
) [32].
Me
O
N
Me
H
Me
Me
NHBoc
·CBr
3
CO
2
H
OH
83
(15 mol%)
O
N
+
N
PMB
SMe
Et
2
O, -40°C, 24 h
then NaBH
4
, CeCl
3
, MeOH
87%
Boc
H
S
Me
N
PMB
81
82
86
(ee = 96%)
1. Cyclization
2. Reduction
[4+2]
Boc
Boc
R
R
NH
NH
OH
X
X
N
R
N
R
H
+
N
SMe
SMe
H
N
PMB
N
PMB
Me
Minfiensine
(
80
)
84
85
SCHEME 6.16
Synthesis of the minfiensin framework.
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