2
580
W. Qiu et al. / Tetrahedron 56 (2000) 2577±2582
Melting points (mp) are uncorrected and were obtained on a
Thomas±Hoover apparatus in open capillaries. All reagents
and solvents, unless otherwise stated, are commercially
available and were used as received. Synthesis of the
Ni(II)-complex of the Schiff base of (S)-BPB and glycine
(1H, m), 2.57±2.63 (1H, m), 3.40 (1H, dd, J9.5, 3.5 Hz),
3.81, 4.37 (2H, AB, J13.5 Hz), 3.99±4.02 (1H, m), 4.05±
4.14 (2H, m), 6.55, 6.74 (2H, ABXY, J 15.8 Hz,
AB
JAXJ 7.6 Hz), 6.74, 6.80 (2H, AB, J8.0 Hz), 7.06±
AY
7.11 (1H, m), 7.18±7.36 (7H, m), 7.44±7.45 (3H, m), 7.48±
1
7
13
(
otherwise stated, R values were taken using ethyl acetate/
S)-1 was accomplished by literature procedure. Unless
7.52 (5H, m), 8.52 (1H, d, J8.5 Hz). C NMR (CDCl ) d
3
23.5, 31.1, 37.9, 56.5, 61.1, 68.7, 70.8, 120.7, 123.6, 124.1,
126.1, 126.5, 127.0, 127.6, 128.0, 128.6, 128.8, 129.2,
129.8, 131.8, 132.1, 132.6, 133.7, 134.2, 134.7, 137.2,
143.1, 171.1, 178.9, 182.2. HRMS (FAB) [M1H] calcd
for C H N NiO 614.1954, found 614.1948.
f
acetone (20/1) as an eluting system. Unless otherwise stated,
yields refer to isolated yields of products of greater than
1 13
5% purity as estimated by H and C NMR spectroscopy.
All new compounds were characterized by H, C NMR
and HRMS.
1
9
1
13
3
6
33
3
3
Ni(II) complex of Schiff base of (S)-BPB and bis-(trans-
2
D
5
General procedure for the reactions of complexes (S)-3
and (S)(2S,R)-4 with cinnamyl halides 5a,b
cinnamyl)glycine (8). R
21028 (c 0.0245, CHCl ). H NMR (CDCl
f
0.52. Mp 194±1958C. [a]
1
) d 1.40±1.43
3
3
(
1H, m), 1.90 (1H, ddd, J17.0, 11.0, 6.5 Hz), 2.12±2.17
To a solution of complex 3 or 4 (10 mmol) in DMF (45 mL)
at 48C (ice water) under oxygen-free atmosphere, KOH
powder (100 mmol) was added with stirring. The mixture
was warmed to room temperature, and trans-cinnamyl
halide 5a,b in DMF (4 mL) was added dropwise. The course
(2H, m), 2.42, 2.63 (2H, ABX, JAB14.5 Hz, JAX9.0 Hz,
J
J
BX5.5 Hz), 2.57, 2.72 (2H, ABX,
J
AB15.5 Hz,
AX6.5 Hz, JBX7.0 Hz), 2.60±2.70 (1H, m), 3.24±3.70
(1H, t, J8.5 Hz), 3.31, 4.30 (2H, AB, J12.5 Hz), 3.54±
3.57 (1H, m), 6.19, 6.56 (2H, ABXY, JAB15.0 Hz,
of the reaction was monitored by TLC (SiO ). Each sample
2
J
J
AXJAY7.0 Hz), 6.63, 6.73 (2H, ABXY, JAB15.0 Hz,
AXJAY8.0 Hz), 6.97 (1H, ddd, J15.5, 8.5, 6.0 Hz),
was quenched with 5% aqueous acetic acid and the products
were extracted with chloroform before being applied to the
TLC plate. Upon disappearance of the starting 3 or 4, the
reaction mixture was poured into icy 5% acetic acid aqueous
solution (200 mL) and stirred with a glass bar to initiate
crystallization. The crystalline product was ®ltered off,
thoroughly washed with water and dried in vacuo to afford
the corresponding diastereomeric products. In the case of
complex (S)-3, resulting complexes 6, 7, and 8 were isolated
by ¯ash chromatography on silica gel using acetone/ethyl
acetate (1/20) as an eluent, to afford diastereomerically pure
7.06±7.17 (5H, m), 7.23±7.29 (2H, m), 7.33±7.37 (3H,
m), 7.46±7.58 (7H, m), 7.81 (1H, d, J8.5 Hz), 8.12 (2H,
1
3
d, J7.5 Hz). C NMR (CDCl
) d 22.8, 30.7, 41.4, 43.3,
3
58.4, 64.2, 70.6, 82.3, 120.6, 123.4, 124.1, 126.3, 126.5,
127.2, 127.5, 127.6, 127.7, 128.1, 128.6, 128.7, 128.8,
129.8, 131.3, 131.4, 133.0, 133.9, 134.2, 134.6, 136.5,
137.1, 137.2, 141.6, 172.8, 180.6, 180.8. HRMS (FAB)
730.2580, found
1
[M1H]
730.2601.
calcd for
C
H
41
N
NiO
3
45
3
8
(emerges ®rst), 6 (emerges second), and 7 (emerges last).
Ni(II) complex of Schiff base of (S)-BPB and (S)-a-trans-
cinnamyl-a-alanine (10). Starting from 5.0 g of (S)(2S,R)-
For yields, ratios of starting compounds (S)-3 and 5a,b, and
products 6, 7, and 8 see Table 1. Alanine derivative (S)(2S)-
10 was puri®ed prior to decomposition on a short silica gel
column using acetone/ethyl acetate (1/20) as an eluent.
4, 5.80 g (94.6%) of 10 was obtained. R
0.40. Mp 123±
). H NMR (CDCl ) d
3
f
2
5
1
1248C. [a]
21928 (c 0.0262, CHCl
D
3
1.26 (3H, s), 1.41±1.47 (1H, m), 1.89±1.95 (1H, ddd,
J17.2, 10.7, 6.5 Hz), 2.07±2.23 (2H, m), 2.57±2.68 (3H,
m), 3.27 (1H, dd, J10.0, 7.0 Hz), 3.49 (1H, ddd, J10.0,
6.5, 2.5 Hz), 3.61, 4.39 (2H, AB, J13.0 Hz), 6.61±6.68
(3H, m), 6.92 (1H, ddd, J15.5, 9.0, 6.5 Hz), 7.09±7.14
(2H, m), 7.23±7.26 (2H, m), 7.31±7.38 (5H, m), 7.41±
7.45 (1H, m), 7.48±7.53 (4H, m), 8.04 (2H, t, J7.0 Hz).
Ni(II) complex of Schiff base of (S)-BPB and (S)-trans-
2
D
5
cinnamylglycine (6). R 0.30. Mp 129±1308C. [a]
f
1
26958 (c 0.0302, CHCl ). H NMR (CDCl ) d 1.52±1.58
3 3
(
(
1H, m), 1.97 (1H, ddd, J17.0, 10.5, 6.5 Hz), 2.13±2.21
1H, m), 2.24±2.30 (1H, m), 2.48, 2.64 (2H, ABXY,
1
3
JAB14.0 Hz, JAX7.0 Hz, JAY4.0 Hz, JBX7.0 Hz,
C NMR (CDCl ) d 22.9, 29.4, 30.5, 43.7, 57.3, 63.4, 70.1,
3
JBY6.0 Hz), 2.82±2.91 (1H, m), 3.31 (1H, dd, J10.5,
78.5, 120.6, 123.8, 124.0, 126.5, 127.0, 127.5, 127.7, 128.0,
128.5, 128.6, 128.8, 128.9, 129.5, 130.6, 131.6, 133.3,
133.4, 134.5, 136.6, 137.1, 141.9, 172.6, 180.4, 181.7.
7
.0 Hz), 3.43 (1H, ddd, J10.0, 6.5, 3.0 Hz), 3.51, 4.35
(
6
6
2H, AB, J12.5 Hz), 4.14 (1H, dd, J6.0, 4.0 Hz), 6.54,
1
.72 (2H, ABXY, J 15.5 Hz, J J 7.5 Hz), 6.65±
HRMS (FAB) [M1H]
628.2110, found 628.2096.
calcd for
C H N NiO
37 35 3 3
AB
AX
AY
.69 (2H, m), 6.99 (1H, m), 7.13±7.19 (2H, m), 7.23±7.34
(
(
(
6H, m), 7.43±7.48 (3H, m), 7.50±7.57 (2H, m), 8.02±8.03
1
3
2H, m), 8.20 (1H, part of AB, J9.0 Hz). C NMR
General procedure for decomposition of complexes
(S)(2S)-(6) and (S)(2S)-(10)
CDCl ) d 23.2, 30.7, 37.7, 57.2, 63.2, 70.3, 70.6, 120.6,
3
1
1
1
23.5, 123.5, 126.3, 126.6, 127.1, 127.7, 127.9, 128.5,
28.8, 128.9, 129.0, 129.8, 131.5, 132.3, 133.2, 133.3,
34.1, 134.7, 137.0, 139.2, 142.7, 171.0, 178.9, 180.4.
Isolation of (S)-trans-cinnamylglycine (1) and (S)-a-
trans-cinnamyl-a-alanine (2) and recovery of chiral
ligand (S)-9. A solution of diastereo- and enantiomerically
pure complex (S)(2S)-(6) or (S)(2S)-(10) (10 mmol) in
MeOH (15 mL) was added dropwise to a mixture of
aqueous 3N HCl and MeOH (1/1) (70 mL) at 708C with
stirring. Upon disappearance of the red color of the starting
complex, the reaction mixture was evaporated and dried in
vacuo to dryness. Conc. NH ´H O (45 mL) was added,
1
HRMS (FAB) [M1H]
614.1954, found 614.1964.
calcd for C H N NiO
36 33 3 3
Ni(II) complex of Schiff base of (S)-BPB and (R)-trans-
2
D
5
cinnamylglycine (7). R 0.25. Mp 202.0±202.58C. [a]
f
1
2
13298 (c 0.0256, CHCl ). H NMR (CDCl ) d 1.20±1.32
3 3
(
1H, m), 1.58±1.69 (2H, m), 2.01±2.04 (1H, m), 2.35±2.42
3
2