F. Mercier et al. / Tetrahedron: Asymmetry 14 (2003) 3137–3140
Table 2. Efficiency of ligands 4–7 in enantioselective allylic N-alkylation
3139
Entrya
Ligand
T (°C)
t (h)
Conversionb
Yield (%)c
Ee (%)d
1
2
4
4
50
20
5
2
100
100
87
91
79 (S)
83 (S)
3
4
5
5
5
5
50
20
0
5
3
24
79
100
100
64
89
100
72 (S)
86 (S)
89 (S)
6
7
6
6
50
20
1
2
100
100
88
85
67 (S)
73 (S)
8
9
1
7
7
7
50
20
0
2
3
20
100
100
100
88
90
94
78 (S)
86 (S)
90 (S)
0
a
b
c
[
Pd(dba) ] 2%, Pd/L=1/3.
2
Determined by TLC and NMR.
Isolated yields.
Measured on a Chiracel OD column, flow rate 1 mL/min, eluent:hexane/ PrOH 200/1, t =22.3 min, t =24.3 min.
d
i
R
S
2
3
.2. Synthesis of phosphanorbornadiene-imines 4–7
JPC=6.0 Hz, bridgehead C), 70.9 (s, CH-N), 63.9 (s,
bridge C), 26.0 (s, MeCHN), 20.8 (s, Me), 16.5 (s, Me).
−
3
A mixture of aldehyde 3 (0.64 g, 2×10 mol), primary
amine (1.2 equiv. for 4, 5, 5a, 6, and 5 equiv. for 7),
PTSA (0.1 equiv.) and MgSO4 (0.1 g) in dry
dichloromethane (14 mL) was stirred at room tempera-
ture for 3–12 h. Solid NaHCO was then added, the
reaction mixture was filtered and dried over Na SO .
After filtration and evaporation of the solvent, the
crude imines were obtained in quantitative yields. Com-
pounds 4, 6, 7 were used as such, compound 5 was
precipitated in pentane, compound 5a was recrystallized
from pure ethanol.
Compound 5a: white yellow pasty solid, [h] =+119
(CH Cl , c=1.0). P NMR (CH Cl ) l −22.0,
NMR (CDCl ) l 8.31 (d, 1H, J =8.40 Hz, CH=N),
7.44–7.00 (15H, Ph), 4.31 (q, 1H, JHH=6.56 Hz, CH-
D
31
1
H
2
2
2
2
3
3
PH
3
3
2
4
N), 2.08 (s, 3H, Me), 2.00 (m, 2H, P-CH ), 1.45 (d, 3H,
2
3
13
JHH=6.56 Hz, MeCHN), 1.38 (s, 3H, Me), C NMR
2
(
1
2
CDCl ) l 172.9 (s), 158.0 (d, J =15.75 Hz, CꢀN),
3
PC
1
1
57.4 (s), 153.0 (d, J =24.0 Hz, C ), 151.2 (d, J =
PC a PC
4.0 Hz, C ), 146.4 (s), 139.8 (d, JPC=21.0 Hz, Ph or
a
vinyl), 137.3 (s), 129.0–128.4 (Ph), 127.3 (s), 127.2 (s),
1
2
26.9 (s), 72.6 (d, JPC=6.0 Hz, bridgehead C), 70.3 (s,
CH-N), 64.3 (s, bridge C), 25.8 (s, MeCHN), 20.8 (s,
Me), 16.6 (s, Me).
3.3. Characterization of imines 4–7
Compound 4: yellow sticky solid, mp 60–70°C, [h]
D
Compound 6: yellow solid, mp 166°C, [h] =−158 (acet-
31
1
D
could not be measured. P NMR (CH Cl ) l −22.3; H
2
2
31
1
one, c=1.0). P NMR (CH Cl ) l −23.2, H NMR
3
2
2
NMR (CDCl ) l 8.06 (d, 1H, J =8.3 Hz, CH=N),
.36–7.11 (13H, Ph), 7.01 (d, 2H, JHH=7.2 Hz, Ph),
.80 (d, 1H, JHH=13.8 Hz, CH N), 4.48 (d, 1H,
JHH=13.8 Hz, CH N), 2.10–2.01 (2H, P-CH ), 2.04 (s,
3
PH
3
3
(CDCl
3
) l 8.14 (d, 1H, JPH=8.40 Hz, CH=N), 7.41–
), 2.10 (s, 3H, Me),
, 75 MHz) l 176.8
(s), 159.3 (d, JPC=15.5 Hz, CꢀN), 157.4 (s), 153.4 (s),
7
2
7.04 (15H, Ph), 2.14 (m, 2H, P-CH
1.42 (s, 3H, Me), C NMR (CDCl
3
2
2
4
2
13
2
2
2
13
3
H, Me), 1.36 (s, 3H, Me), C NMR (CDCl ) l 173.5
3
2
1
1
153.1 (d, JPC=25.5 Hz, C
), 150.9 (d, JPC=24.0 Hz,
a
(
s), 160.8 (d, J =11.25 Hz, CꢀN), 157.0 (s), 152.4 (d,
PC
1
1
C ), 139.5 (d, JPC=21.0 Hz, Ph or vinyl), 137.0 (s),
a
JPC=24.75 Hz, C ), 150.7 (d,
J =24.0 Hz, C ),
PC a
a
1
30–128.5 (Ph), 127.1 (s), 126.1 (s), 121.5 (s), 72.9 (d,
1
1
5
40.3 (s), 139.3 (d, JPC=21.0 Hz, Ph or vinyl), 136.8 (s),
28.9–128.1 (Ph), 127.0 (s), 126.7 (s), 72.4 (d, JPC=
2
JPC=6.0 Hz, bridgehead C), 64.7 (s, bridge C), 20.9 (s,
Me), 16.6 (s, Me).
.25 Hz, bridgehead C), 65.5 (s, CH N), 64.0 (s, bridge
2
C), 20.6 (s, Me), 16.3 (s, Me).
Compound 7: white solid, mp 124°C, [h] =−158
D
31
1
(
CHCl , c=0.9). P NMR (CH Cl ) l −22.5, H NMR
3 2 2
3
Compound 5: white solid, mp 67–68°C, [h] =−252
D
3
1
1
(CDCl ) l 7.86 (d, 1H, J =8.0 Hz, CHꢀN), 7.32–
(
(
7
1
(
1
(
2
1
1
CHCl , c=1.0). P NMR (CH Cl ) l −21.6, H NMR
3
PH
3
2
2
3
7
.10 (8H, Ph), 6.95 (d, 2H, JHH=7.5 Hz, Ph), 1.99 (s,
H, Me), 1.95 (m, 2H, P-CH ), 1.32 (s, 3H, Me), 1.08
CDCl ) l 8.02 (d, 1H, J =8.30 Hz, CHꢀN), 7.38–
.12 (13H, Ph), 7.01 (d, 2H, J =7.2 Hz, Ph), 4.27 (q,
H, J =6.56 Hz, CH-N), 2.05 (m, 2H, P-CH ), 2.03
s, 3H, Me), 1.55 (d, 3H, JHH=6.56 Hz, MeCHN),
.39 (s, 3H, Me), C NMR (CDCl ) l 173.1 (s), 158.3
d, J =14.25 Hz, C=N), 156.5 (s), 152.9 (d, JPC=
3
PH
3
2
HH
3
t
13
(s, 9H, Bu), C NMR (CDCl ) l 171.6 (s), 157.5 (s),
3
2 1
HH
2
3
154.0 (d, JPC=15.0 Hz, CꢀN), 153.6 (d, JPC=23.25
1
1
3
Hz, C ), 151.2 (d, JPC=24.0 Hz, C ), 139.8 (d, JPC=
a a
3
2
1
21.0 Hz, Ph or vinyl), 137.5 (s), 128.8 (d, JPC=8.25 Hz,
Ph), 128.8 (s), 128.7 (s), 128.3 (s), 126.8 (s), 72.5 (d,
JPC=6.0 Hz, bridgehead C), 63.9 (s, bridge C), 58.1 (s,
Me C-N), 30.4 (s, Me C-N), 20.9 (s, Me), 16.5 (s, Me).
PC
1
4.0 Hz, C ), 151.2 (d, J =24.0 Hz, C ), 146.5 (s),
a PC a
39.6 (d, JPC=21.0 Hz, Ph or vinyl), 137.3 (s), 128.9–
28.4 (Ph), 127.3 (s), 127.2 (s), 126.9 (s), 72.6 (d,
3
3