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O
O
30 R=Ph
31 R= i Pr
32 R= t Bu
33 R=Me
O
O
Ph
Ph
P
Cl
O
O
HO
O
O
P
N
base
15-48%
N
O
O
Ref. [18a]
O
29
HO
HO
R
R
R 1
O
R 2
O
HO
O
O
H 2 N OH
P
Cl
O
R 1
a R 1 =R 2 = t Bu
b R 1 = t Bu, R 2 =OMe
c R 1 =SiMe 3 , R 2 =H
Ph
O
O
O
Ph
O
O
O
R 2
28
HO
P
Cl
base
O
base
15-48%
H 2 N
O
P
NH OMe
OMe
O
P
O
34
35
O
Scheme 13.10 Synthesis of oxazoline-phosphite ligands 30-33, and phosphite-phosphora-
midite ligands 35.
O
O
O
O
O
OH
OOH
O
OH
O
O
O
O
O
OH
O
O
O
O
O O
O O
O O
O
O
OH
O
40
39
36
37
38
O
O
O
O
O
O
O
O
O
O
P Cl
P Cl
P Cl
P Cl
P Cl
O
O
O
O
O
O
O
O
O
O
P
O
OO P
P
O
O
O
O
O
O
O
O
O
O
O
O
O
P
O
O
O
O
O
O O
O O
O
O O
O
P
O
41
D-gluco
42
D-allo
43
D-galacto
44
D-fructo
45
D-fructo
R 1
R 2
R 3
O
O
=
O
O
O
O
R 1
R 2
R 3
a R 1 =R 2 = H
b R 1 = t Bu, R 2 = OMe
c R 1 =R 2 = t Bu
d R 1 = SiMe 3 , R 2 = H
e ( S ) ax R 3 = H
f ( R ) ax R 3 = H
Scheme 13.11
Synthesis of phosphite ligands 41-45.
Ligands 30-34 and 35 provided moderate to low conversions and enantioselec-
tivities in the Ni-catalyzed asymmetric addition of trimethylaluminium to benzal-
dehyde and other benchmark aldehydes. The best enantioselectivity (59%) was
obtained in the addition of AlMe 3 to benzaldehyde in the presence of ligand 32a,
but the conversion was very low.
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