Chemistry Reference
In-Depth Information
Ph
(
R
)-BINAP,
HCO
2
H, Et
3
N
Ph
Br
Ph
Br
(Ph
3
P)
4
Pd, KOAc
Ph
5.183
5.185
5.182
Br
Br
n
-C
5
H
11
(Ph
3
P)
4
Pd, KOAc
n
-C
5
H
11
5.184
PdL
n
Br
(Ph
3
P)
4
Pd, KOAc
5.186
n
-C
5
H
11
5.187
Scheme 5.51
Cl
MeO
2
C
MeO
2
C
Cl
(Ph
3
P)
2
PdCl
2
HCO
2
-
N
N
I
N
5.189
PdLI
N
H
5.188
5.190
MeO
2
C
Cl
Cl
HN
N
HBr, AcOH
N
N
5
.
1
5
1
9
Scheme 5.52
ClZn
I
I
(Ph
3
P)
2
PdCl
2
5.193
5.194
Scheme 5.53
of diiodide
5.193
to the tetracycle
5.194
, in which Negishi coupling is followed by an intramolecular Heck
reaction.
A tandem double Heck reaction was employed to build the steroid ring system from dibromide
5.196
and alkene
5.195
(Scheme 5.54).
56
The first Heck reaction involves the vinyl bromide and results in alkene
migration giving intermediate
5.197
in preparation for the second Heck reaction, involving the aryl bromide.
