Chemistry Reference
In-Depth Information
Me
Me
Me
1) Rh
2
(
R
-DOSP)
4
2,2-DMB, r.t., 2h
Me
17
2
Me
Me
H
H
2) H
2
, Pd/C
3) LiAlH
4
Me
MeO
2
C
Me
Me
HO
N
2
174
175
173
31% (62%) yield (3 steps)
90% ee
(+)-Erogorgiaene
O
Me
HO
Me
H
TBSO
Me
TBSO
Me
Me
O
MeO
Me
MeO
H
1) Rh
2
(
R
-DOSP)
4
2,2-DMB, r.t., 2h
178
Me
Me
(-)-Colombiasin A
176
H
TBSO
2) H
2
, Pd/C
3) LiAlH
4
TBSO
OH
Me
Me
MeO
2
C
Me
O
HO
N
2
177
Me
O
H
Me
34% (68%) yield (3 steps)
>95% ee
173
H
Me
179
(-)-Elisapterosin B
Scheme 4.50.
Synthetic applications of the combined C-H activation/Cope rearrangement.
O
TBS
MeO
2
C
N
2
OTBS
MeO
2
C
MeO
2
C
Rh
2
(
S
-DOSP)
4
OTBS
R'
R'
53-94% yield
>98% de
78-93% ee
R
R'
R
R
173
180
181
182
Δ
R' =
Me
Ph
(
E
)-CH=CHMe
R =
Me
Et
(
E
)-CH=CHPh
or
W
μ
Scheme 4.51.
Combined C - H activation/siloxy - Cope rearrangement.
tive strategy. However, the Cope rearrangement in this sequence is not an energetically
favored process [66]. In this context, the combined C-H activation/Cope rearrangement
reaction of rhodium vinylcarbenoids can be considered a surrogate for the tandem
Claisen/Cope rearrangement (Scheme 4.52) [66]. Products of the combined C- H activa-
tion/siloxy-Cope rearrangement can be classically derived from a tandem aldol reaction/
