Chemistry Reference
In-Depth Information
OMe
OMe
OBn
1. BF
3
, EtSH
2. ArCO
3
H, H
+
(Ph
3
P)
2
Pd(O
2
CCF
3
),
pempidine,
Δ
OBn
I
N
N
DBS
DBS
5.109
5.108
OMe
OMe
1. TPAP, NMO
2. H
2
, H
2
CO, Pd(OH)
2
OH
O
OH
N
N
O
DBS
DBS
5
.
1
0
5
.
1
OMe
OH
DBS =
OH
O
O
O
NO
2
MeN
MeN
Ar =
5.113
5.112
O
2
N
Scheme 5.34
OTf
Pd(OAc)
2
, Et
3
N,
(
S
,
S
)-DIOP
Pd(OAc)
2
, Et
3
N,
(
R
,
R
)-DIOP
O
O
O
5.114
5
.
5
5
1
1
Scheme 5.35
MeO
2
C
CO
2
Me
CO
2
Me
Pd(OAc)
2
, Ag
2
CO
3
,
(
S
)-BINAP
Pd(OAc)
2
, Ag
2
CO
3
,
(
R
)-BINAP
I
H
H
5.117
5
.
1
1
8
5
.
1
1
9
Scheme 5.36
intermediate is involved. Both the e.e. and the sense of stereochemical induction can be different depending
on the conditions (Scheme 5.37).
35
The enantiotopic alkene approach was used in a synthesis of vernolepin
5.128
, with
-hydride elim-
ination proceeding away from the original alkene site, leading to a ketone
5.124
after tautomerization
(Scheme 5.38).
36
After a series of functional group interconversions and protecting group manipulation steps,
a known
37
intermediate
5.127
for vernolepin could be synthesized. When taken through to the end, this work
also served to determine the absolute stereochemistry of this natural product.
