Chemistry Reference
In-Depth Information
PdL
2
Nuc
OAc
L
2
Pd
Nuc
Ph
Ph
Ph
Ph
Ph
Ph
9.125
9.126
9.127
Scheme 9.39
A number of such ligands have been developed. They typically include a diphenylphosphino aryl unit
connected to a chiral group. Bisamides
9.128
derived from
trans
-1,2-diaminocyclohexane, and also other
diamines, have proved valuable,
52
as have phosphinooxazoline derivatives, such as
9.129
.
53
O
O
O
NH
HN
Ph
2
P
N
PPh
2
Ph
2
P
9.128
9.129
The use of chiral ligands has also been employed with
meso
-substrates in which there are two leaving groups
available, which would lead to enantiomeric products. In this way, the adenosine nucleoside
9.137
could be
prepared from a
meso
di-benzoate
9.131
, itself available by oxidation of furan
9.130
(Scheme 9.40).
54
O
9.130
Cl
Cl
N
Pb(OBz)
4
N
N
N
dba
3
Pd
2
.CHCl
3
, L*
O
+
N
BzO
BzO
OBz
N
H
O
N
9.131
9.132
9.133
Cl
BnO
2
C
CO
2
Bn
N
N
OCO
2
Bn
CO
2
Bn
CO
2
Bn
OCO
2
Bn
1. OsO
4
, NMO
2. Me
2
C(OMe)
2
, H
+
Pd(0), Cs
2
CO
3
N
N
O
9.134
Cl
Cl
N
N
N
N
OCO
2
Bn
CO
2
Bn
CO
2
Bn
1. H
2
, Pd/C
2. ArSO
2
Cl, Et
3
N
3. HOBT, DCC, NaBH
4
OH
N
N
N
N
O
O
OO
OO
9.135
9.136
NH
2
Ph
Ph
N
O
O
N
1. NH
3
2. H
3
O
+
NH
HN
OH
N
N
L*=
9.138
O
PPh
2
Ph
2
P
9.137
HO
OH
Scheme 9.40
