M. Li et al. / Tetrahedron: Asymmetry 14 (2003) 3347–3352
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4.7. 1-[(S)-4-tert-Butyl-2,5-oxazolinyl]-1%-(a-diphenylhy-
droxymethyl)-2-(Rp)-methylferrocene (S,Rp)-2b
ether (3×10 mL) and washed with brine (2×10 mL) and
dried over Na2SO4. After removing the solvent under
vacuum, the residue was purified by column chro-
matography with ethyl acetate: petroleum (60–90°C,
1:10) as an eluent to afford 5a (576 mg, 93%) as orange
Compound 4b (340 mg, 0.6 mmol) was allowed to react
according to the procedure for 2a to afford 2b (243 mg,
80%) as an orange solid; mp 156–158°C. [h]2D0=−358 (c
1
oil. [h]2D0=+49 (c 0.195, CHCl3); H NMR (300 MHz,
1
0.27, CHCl3); H NMR (300 MHz, CDCl3): l 0.99 (s,
CDCl3): l −0.11 (s, 9H), 0.19 (s, 9H), 0.90 (d, J=6.73
Hz, 3H), 1.00 (d, J=6.74 Hz, 3H), 1.73–1.81 (m, 1H),
3.59 (s, 1H), 3.84–3.96 (m, 3H), 4.12–4.25 (m, 5H), 4.63
(s, 1H), 7.12–7.31 (m, 10H); MS (EI) m/z (rel.) 623
(M+, 100), 624 (55), 378 (19), 292 (25); IR (KBr): 2957,
2898, 1656, 1492, 1445, 1263, 1251, 1102, 1072, 505
cm−1. Anal. calcd for C35H45FeNO2Si2: C, 67.39; H,
7.27; N, 2.25. Found: C, 66.90; H, 7.27; N, 2.18.
9H), 2.19 (s, 3H), 3.80 (s, 1H), 3.91 (s, 1H), 4.00–4.06
(m, 2H), 4.13–4.23 (m, 5H), 4.65–4.72 (m, 1H), 5.05 (br,
1H), 7.11–7.24 (m, 6H), 7.31–7.36 (m, 2H), 7.48–7.51
(m, 2H); MS (EI) m/z (rel.) 507 (M+, 25), 508 (24), 230
(77), 229 (100), 148 (44); IR (KBr): 3313, 2961, 1639,
1491, 1307, 1217, 1083, 490 cm−1. Anal. calcd for
C31H33FeNO2: C, 73.37; H, 6.55; N, 2.76. Found: C,
73.39; H, 6.65; N, 2.70.
4.11. 1-[(S)-4-tert-Butyl-2,5-oxazolinyl]-1%-(a-diphenyl-
trimethylsiloxymethyl)-2-(Sp)-trimthylsilylferrocene
(S,Sp)-5b
4.8. 1-[(S)-4-Benzyl-2,5-oxazolinyl]-1%-(a-diphenylhy-
droxymethyl)-2-(Rp)-methylferrocene (S,Rp)-2c
Compound 4c (360 mg, 0.6 mmol) was allowed to react
according to the procedure for 2a to afford 2c (208 mg,
64%) as an orange solid; mp 52–55°C. [h]2D0=−224 (c
Compound 4b (900 mg, 1.6 mmol) was allowed to react
according to the procedure for 5a to afford 5b (901 mg,
89%) as orange oil. [h]2D0=+129 (c 0.09, CHCl3); 1H
NMR (300 MHz, CDCl3): l −0.11 (s, 9H), 0.19 (s, 9H),
0.94 (s, 9H), 3.68–3.69 (m, 1H), 3.85 (dd, J=8.1 Hz, 9.9
Hz, 1H), 3.92 (t, J=2.4 Hz, 1H), 4.03 (t, J=8.4 Hz,
1H), 4.10–4.14 (m, 1H), 4.17–4.21 (m, 3H), 4.24–4.26
(m, 1H), 4.64–4.65 (m, 1H), 7.12–7.25 (m, 5H), 7.26–
7.29 (m, 5H); MS (EI) m/z (rel.) 637 (M+, 100), 638
(99), 392 (17), 292 (56), 229 (22), 73 (17); IR (KBr):
3088, 2955, 1658, 1492, 1263, 1251, 1141, 1072, 491
cm−1. Anal. calcd for C36H47FeNO2Si2: C, 67.80; H,
7.43; N, 2.20. Found: C, 67.82; H, 7.45; N, 2.11.
1
0.10, CHCl3); H NMR (300 MHz, CDCl3): l 2.17 (s,
3H), 2.74 (dd, J=8.2 Hz, 13.6 Hz, 1H), 3.14 (dd,
J=5.1 Hz, 13.7 Hz, 1H), 3.87 (t, J=5.3 Hz, 1H),
3.91–3.93 (m, 1H), 4.04–4.07 (m, 1H), 4.09–4.12 (m,
2H), 4.16–4.18 (m, 1H), 4.21–4.23 (m, 1H), 4.28 (t,
J=9.0 Hz, 1H), 4.47–4.57 (m, 1H), 4.67–4.68 (m, 1H),
4.82 (s, 1H), 7.24–7.35 (m, 13H), 7.45–7.47 (m, 2H);
MS (EI) m/z (rel.) 541 (M+, 77), 542 (31), 311 (34), 293
(100), 229 (32), 91 (68); IR (KBr): 3526, 3085, 2920,
1647, 1602, 1444, 1152, 1017, 492 cm−1. Anal. calcd for
C34H31FeNO2: C, 75.42; H, 5.77; N, 2.59. Found: C,
75.21; H, 6.06; N, 2.46.
4.12. 1-[(S)-4-Isopropyl-2,5-oxazolinyl]-1%-(a-diphenylhy-
droxymethyl)-2-(Sp)-methylferrocene (S,Sp)-3a
4.9. 1-[(R)-4-Phenyl-2,5-oxazolinyl]-1%-(a-diphenylhy-
droxymethyl)-2-(Sp)-methylferrocene (R,Sp)-2d
Ferrocene 5a (310 mg, 0.5 mmol) was dissolved in 6 mL
of Et2O at room temperature and treated with n-BuLi
(0.38 mL, 0.6 mmol, 1.6 M in hexane). After stirring for
1 h at this temperature, methyl iodide (1.2 mmol) was
added and the mixture was stirred for an additional 1 h.
The reaction mixture was quenched with water (10 mL)
and extracted with ethyl ether (3×10 mL), washed with
brine (2×10 mL) and dried over Na2SO4. After remov-
ing the solvent under in vacuum, the residue was
purified by flash column chromatography with ethyl
acetate: petroleum (60–90°C, 1:30) as an eluent to
afford orange oil. The product was directly dissolved in
6 mL of THF and TBAF (5 mL, 5 mmol, 1.0 M in
THF) was added to the solution. After the mixture was
refluxed for 8 h, water (5 mL) was added and extracted
with dichloromethane (3×10 mL), washed with brine
(2×10 mL), dried over Na2SO4. After removing the
solvent under in vacuum, the residue was purified by
column chromatography with ethyl acetate: petroleum
(60–90°C, 1:5) as an eluent to afford 3a (165 mg, 67%)
as orange foam; mp 50–53°C. [h]2D0=+136 (c 0.23,
Compound 4d (350 mg, 0.6 mmol) was allowed to react
according to the procedure for 2a to afford 2d (212 mg,
67%) as an orange solid; mp 128–130°C. [h]2D0=+284 (c
1
0.10, CHCl3); H NMR (300 MHz, CDCl3): l 2.22 (s,
3H), 3.91 (s, 1H), 3.95 (s, 1H), 4.10–4.33 (m, 6H),
4.65–4.76 (m, 2H), 5.31 (br, 1H), 7.15–7.25 (m, 6H),
7.29–7.47 (m, 9H); MS (EI) m/z (rel.) 527 (M+, 16), 105
(53), 77 (56), 43 (100); IR (KBr): 3295, 2903, 1633,
1601, 1491, 1218, 1077, 4 cm−1. Anal. calcd for
C33H29FeNO2: C, 75.15; H, 5.54; N, 2.66. Found: C,
75.17; H, 5.76; N, 2.52.
4.10. 1-[(S)-4-Isopropyl-2,5-oxazolinyl]-1%-(a-diphenyl-
trimethylsiloxymethyl)-2-(Sp)-trimthylsilylferrocene
(S,Sp)-5a
A solution of ferrocene 4a (550 mg, 1.0 mmol),
TMEDA (139 mg, 1.2 mmol) in 12 mL of Et2O was
cooled to −78°C and treated with n-BuLi (0.75 mL, 1.2
mmol, 1.6 M in hexane). After stirring for 2 h at this
temperature, chlorotrimethylsilane (152 mg, 1.4 mmol)
was added and the mixture was stirred at 0°C for an
additional 1 h. The reaction mixture was quenched with
saturated NaHCO3 (10 mL), then extracted with ethyl
1
CHCl3); H NMR (300 MHz, CDCl3): 0.90 (d, J=6.7
Hz, 3H), 1.04 (d, J=6.7 Hz, 3H), 1.77–1.84 (m, 1H),
2.15 (s, 3H), 3.83–4.03 (m, 4H), 4.10–4.32 (m, 5H),
4.68–4.76 (m, 2H), 7.15–7.47 (m, 8H), 7.47–7.50 (m,
2H); MS (EI) m/z (rel.) 493 (M+, 100), 492 (73), 494