S.-F. Zhu et al. / Tetrahedron: Asymmetry 14 (2003) 3219–3224
3223
%): 404 (M+, 100). HR-MS (FAB) calcd for C29H24O2:
404.1776. Found: 404.1776.
141.3, 140.8, 140.7, 135.1, 134.7, 129.0, 128.8, 128.7,
128.6, 128.3, 128.2, 126.8, 122.4, 121.9, 121.8, 59.4,
38.3, 38.2, 35.6, 35.3, 31.1, 30.7. 31P NMR (121 MHz,
CDCl3): l 124.6. MS (m/z, %): 477 (M+, 100). Anal.
calcd for C31H28NO2P: C, 77.97, H, 5.91, N, 2.93.
Found: C, 77.83, H, 5.91, N, 2.94.
4.6. (S)-4,4%-Dimethoxy-7,7%-dihydroxy-1,1%-spirobiin-
dane (S)-13
A 100 mL over dried Schlenk tube was flashed with
nitrogen, charged with sodium (0.4 g, 18 mmol), and
was added 5.5 mL methanol gently while stirring. After
the sodium was completely dissolved, methanol was
removed under vacuum. Then anhydrous CuCl (28 mg,
0.26 mmol), (S)-10 (660 mg, 1.6 mmol) and dry DMF
were added. After refluxed for 12 h with stirring at
120°C, the solvent was removed under vacuum. 20 mL
cold water was then added with stirring to the residue
in 15 min. The mixture was neutralized with 40 mL 2 N
HCl to pH 2, stirred for another 15 min and extracted
with chloroform (3×30 mL). The organic layers were
combined and washed with brine, dried over anhydrous
MgSO4. After evaporation of solvent, the residue was
chromatographed on silica gel column eluting with
CH2Cl2 to afford (S)-13 (350 mg, 70%) as a white solid.
Mp 199–200°C. [h]2D5 −16 (c 0.5, CH2Cl2). 1H NMR
(200 MHz, CDCl3): l 6.66 (d, J=1.9 Hz, 4H), 4.26 (s,
2H), 3.80 (s, 6H), 3.19–2.97 (m, 4H), 2.29–2.19 (m, 4H).
13C NMR (100 MHz, CDCl3): l 150.4, 146.7, 132.9,
132.4, 115.4, 114.8, 111.8, 111.2, 58.7, 56.0, 55.7, 37.7,
28.1, 28.0. MS (m/z, %): 312 (M+, 100). Anal. calcd for
C19H20O4: C, 73.06, H, 6.45. Found: C, 72.92, H, 6.56.
4.9. (S)-O,O%-[4,4%-Dimethoxy-1,1%-spirobiindane-7,7%-
diyl]-N,N-dimethylphosphoramidite (S)-6c
By the same procedure as that for (S)-6a, phospo-
ramidite (S)-6c was synthesized from (S)-13 (190 mg,
0.6 mmol) as a white solid (200 mg, 90%). Mp 219-
1
220°C. [h]2D5 −220 (c 0.5, CH2Cl2). H NMR (300 MHz,
CDCl3): l 6.91 (d, J=9.0 Hz, 1H), 6.72–6.62 (m, 3H),
3.83 (s, 6H), 2.87 (d, J=7.2 Hz, 4H), 2.34 (d, J=9.3
Hz, 6H), 2.30–2.10 (m, 2H), 2.06–1.85 (m, 2H). 13C
NMR (75 MHz, CDCl3): l 152.9, 143.4, 142.2, 139.8,
132.9, 132.2, 122.3, 122.0, 110.0, 60.0, 55.7, 38.5, 38.3,
35.8, 35.5, 27.7, 27.4, 1.2. 31P NMR (121 MHz, CDCl3):
l 125.3. MS (m/z, %): 385 (M+, 100). Anal. calcd for
C21H24NO4P: C, 65.45, H, 6.28, N, 3.63. Found: C,
65.45, H, 6.31, N, 3.53.
4.10. General procedure for asymmetric hydrogenation
of methyl 2-acetamidocinnamates
To a Schlenk tube equipped with septum and stirring
bar 2.0 mg (5 mmol) of Rh(COD)2BF4, 11 mmol of
ligand and 0.5 mmol of substrate were added. After
three vacuum/hydrogen cycles, 5 mL of solvent was
added by a syringe and the reaction mixture was left
stirring at 0°C under ambient H2 pressure till the
reaction was completed. The resulting mixture was
filtered through a short silica gel column and concen-
trated under reduced pressure to give hydrogenation
product in quantitative yield. The ee value of product
was determined by chiral GC. The analytic conditions
are as follows.
4.7. (S)-O,O%-[4,4%-Dibromo-1,1%-spirobiindane-7,7%-diyl]-
N,N-dimethylphosphoramidite (S)-6a
A mixture of (S)-10 (410 mg, 1.0 mmol) and HMPT
(0.3 mL, 1.5 mmol) in 5 mL dry toluene was heated at
reflux under argon for 3 h. After cooling to rt, the
mixture was concentrated and purified by chromatogra-
phy on a silica gel column eluting with petroleum
ether/EtOAc (15:1) to give (S)-6a as a white solid (400
mg, 83%). Mp 215.5–216°C. [h]2D5 −208 (c 0.5, CH2Cl2).
1H NMR (300 MHz, CDCl3): l 7.35–7.27 (m, 2H), 6.84
(d, J=8.7 Hz, 1H), 6.56 (d, J=8.4 Hz, 1H), 3.00–2.86
(m, 4H), 2.35 (d, J=9.0 Hz, 6H), 2.30–2.22 (m, 2H),
2.20–1.98 (m, 2H). 13C NMR (75 MHz, CDCl3): l
147.6, 147.5, 145.5, 144.9, 143.5, 142.2, 131.6, 131.4,
123.8, 123.4, 115.5, 114.8, 61.2, 37.6, 37.4, 35.6, 35.3,
32.4, 32.1. 31P NMR (121 MHz, CDCl3): l 125.5. MS
(m/z, %): 483 (M+, 91), 60 (100). Anal. calcd for
C19H18Br2NO2P: C, 47.23, H, 3.76, N, 2.90. Found: C,
47.23, H, 4.00, N, 3.04.
2-Acetamido-3-phenylpropanoate: Chrompack Chirasil-
L-Val column (25 m×0.25 mm i.d.), programmed to
increase at 4°C/min from 90°C to 190°C, TR=17.60
and 18.34 min.
2-Acetamido-3-(4-chlorophenyl)propanoate: Chrompack
Chirasil-L-Val column (25 m×0.25 mm i.d.), at 160°C
constant, TR=13.79 and 15.53 min.
2-Acetamido-3-(4-methoxylphenyl)propanoate: Chrom-
pack Chirasil-L-Val (25 m×0.25 mm i.d.), at 160°C
constant, TR=16.48 and 18.34 min.
4.8. (S)-O,O%-[4,4%-Diphenyl-1,1%-spirobiindane-7,7%-diyl]-
N,N-dimethylphosphoramidite (S)-6b
2-Acetamido-3-(4-nitrophenyl)propanoate: Chrompack
Chirasil-L-Val (25 m×0.25 mm i.d.), programmed to
increase at 2°C/min from 160 to 200°C, then at con-
stant 200°C, TR=19.71 and 20.62 min.
By the same procedure as that for (S)-6a, phospho-
ramidite (S)-6b was synthesized from (S)-12 (404 mg,
1.0 mmol) as a white solid (358 mg, 75%). Mp 196.5–
1
198°C. [h]2D5 −216 (c 0.5, CH2Cl2). H NMR (300 MHz,
CDCl3): l 7.48–7.24 (m, 10H), 7.24–7.05 (m, 2H), 7.04
(d, J=8.1 Hz, 1H), 6.79 (d, J=8.4 Hz, 1H), 3.25–3.18
(m, 2H), 2.86–2.78 (m, 2H), 2.41 (d, J=8.7 Hz, 6H),
2.37–2.32 (m, 2H), 2.16–1.94 (m, 2H). 13C NMR (75
MHz, CDCl3): l 147.8, 145.5, 143.3, 142.7, 142.5,
4.11. General procedure for asymmetric hydrogenation
of 1-arylethenyl acetamides
1-Arylethenyl acetamide (0.5 mmol), [Rh(COD)2]BF4
(2.0 mg, 5 mmol) and 11 mmol of ligand were mixed