C. Palomo et al. / Tetrahedron 56 (2000) 5563±5570
5567
1740 cm21 (CvO), 843 (C±Si). MS (m/z, rel. int.) 55(19),
73(75), 82(20), 91(9), 104(100), 217(11). 1H NMR (CDCl3,
d ppm) 7.50±7.34 (m, 5H); 5.07 (dd, 1H, J2.0 Hz,
J8.2 Hz); 4.60 (t, 1H, J8.4 Hz); 4.34 (dd, 1H,
J2.0 Hz, J8.6 Hz); 3.66 (d, 1H, J6.6 Hz); 3.46 (d,
1H, J6.6 Hz); 2.74 (s, 1H); 1.60±1.49 (m, 1H); 1.27±
1.12 (m, 1H); 0.78 (t, 3H, J7.3 Hz); 0.15 (s, 9H); 0.13
(s, 9H). 13C NMR (CDCl3, d ppm) 165.0, 156.8, 140.4,
128.8, 128.7, 127.2, 72.0, 71.1, 59.5, 58.1, 37.0, 25.2, 8.8,
20.3, 20.4. Anal. calcd for C21H35N2O3Si2 (419.56): C,
60.11; H, 8.42; N, 6.67. Found: C, 60.32; H, 8.50; N, 6.51.
Anal. calcd for C26H36N2O3Si2 (480.62): C, 64.97; H,
7.56; N, 5.83. Found: C, 64.89; H, 7.60; N, 5.92.
(3R)-1-[Bis(trimethylsilyl)methyl]-3-[(4-methylphenyl)-
methyl]-3-[(4S)-2-oxo-4-phenyloxazolidin-3-yl] azetidin-
2-one (17g). The general procedure was followed using
p-methylbenzyl bromide (3.70 g, 20 mmol) as the alkyl
halide. Yield 75%. Mp: 143±1458C (hexane). [a]2D5
122.0 (c1.0, CH2Cl2). IR (KBr) n 1731 cm21 (CvO),
840 (C±Si). MS (m/z, rel. int.) 73(100), 91(14), 104(32),
105(21), 131(17), 158(12), 293(53), 294(11). 1H NMR
(CDCl3, d ppm) 7.63±7.59 (m, 2H); 7.42±6.90 (m, 7H);
5.13 (dd, 1H, J1.1 Hz, J6.5 Hz); 4.60 (t, 1H,
J8.5 Hz); 4.42 (dd, 1H, J1.7 Hz, J8.6 Hz); 3.46 (d,
1H, J6.5 Hz); 3.40 (d, 1H, J6.4 Hz); 2.77 (d, 1H,
J13.5 Hz); 2.48 (s, 1H); 2.21 (s, 3H); 2.16 (d, 1H,
J13.9 Hz); 20.03 (s, 9H); 20.20 (s, 9H). 13C NMR
(CDCl3, d ppm) 164.1, 156.7, 140.1, 136.5, 131.6, 130.4,
129.2, 129.0, 127.7, 72.0, 71.2, 59.8, 52.1, 37.3, 36.8, 20.8,
20.6, 20.8. Anal. calcd for C27H38N2O3Si2(494.92): C,
65.52; H, 7.75; N, 5.66. Found: C, 65.01; H, 7.94; N, 5.83.
(3R)-1-[Bis(trimethylsilyl)methyl]-3-(3-methylpropyl)-
[(4S)-2-oxo-4-phenyloxazolidin-3-yl]azetidin-2-one (17d).
The general procedure was followed using isobutyl bromide
(2.17 mL, 20 mmol) as the alkyl halide. Yield 62%. Mp:
99±1008C (hexane). [a]2D5226.8 (c0.59, CH2Cl2). IR
(KBr) n 1738 cm21 (CvO), 848 (C±Si). MS (m/z, rel.
int.) 68(96), 73(100), 104(99), 118(39), 204(98), 205(41),
246(37). 1H NMR (CDCl3, d ppm) 7.47±7.33 (m, 5H); 5.19
(dd, 1H, J2.3 Hz, J8.4 Hz); 4.61 (t, 1H, J8.6 Hz); 4.41
(dd, 1H, J2.3 Hz, J8.4 Hz); 3.89 (d, 1H, J6.8 Hz); 3.50
(d, 1H, J6.8 Hz); 2.70 (s, 1H); 1.63±1.30 (m, 3H); 0.89 (d,
3H, J6.3 Hz); 0.49 (d, 3H, J6.3 Hz); 0.15 (s, 9H); 0.12
(s, 9H). 13C NMR (CDCl3, d ppm) 165.9, 140.4, 128.8,
127.7, 71.0, 70.7, 59.5, 54.5, 41.9, 37.0, 24.1, 22.9, 20.2,
20.3. Anal. calcd for C23H38N2O3Si2(446.74): C, 61.84; H,
8.57; N, 6.27. Found: C, 61.51; H, 8.25; N, 6.40.
(3R)-1-[Bis(trimethylsilyl)methyl]-3-[(2-methylphenyl)-
methyl]-3-[(4S)-2-oxo-4-phenyloxazolidin-3-yl]azetidin-
2-one (17h). The general procedure was followed using
o-methylbenzyl bromide (3.70 g, 20 mmol) as the alkyl
halide. Yield 80%. Mp: 152±1538C (hexane). [a]2D5
132.1 (c1.0, CH2Cl2). IR (KBr) n 1728 cm21 (CvO),
840 (C±Si). MS (m/z, rel. int.) 73(100), 91(13), 103(15),
104(25), 130(82), 158(7), 293(34), 294(8). 1H NMR
(CDCl3, d ppm) 7.66±7.62 (m, 3H); 7.41±7.35 (m, 2H);
7.05±7.00 (m, 2H); 5.15 (dd, 1H, J1.5 Hz, J8.1 Hz);
4.64 (t, 1H, J8.3 Hz); 4.45 (dd, 1H, J1.5 Hz,
J8.8 Hz); 3.48 (d, 1H, J6.6 Hz); 3.34 (d, 1H,
J6.6 Hz); 2.88(d,1H, J14.1 Hz); 2.51 (s, 1H); 2.20 (d,
1H, J13.4 Hz); 2.18 (s, 3H); 20.02 (s, 9H); 20.19 (s, 9H).
13C NMR (CDCl3, d ppm) 164.2, 156.8, 140.3, 137.5, 133.4,
131.4, 130.5, 129.0, 127.8, 127.2, 126.1, 71.9, 71.2, 59.9,
52.2, 37.5, 34.3, 19.5, 20.6, 20.7. Anal. calcd for
C27H38N2O3Si2 (494.92): C, 65.52; H, 7.75; N, 5.66.
Found: C, 65.05; H, 7.94; N, 5.80.
(3R)-3-Allyl-1-[bis(trimethylsilyl)methyl]-3-[(4S)-2-oxo-
4-phenyloxazolidin-3-yl]azetidin-2-one (17e). The general
procedure was followed using allyl bromide (1.73 mL,
20 mmol) as the alkyl halide. Yield 70%. Mp: 111±1128C
(hexane). [a]2D5216.8 (c1.0, CH2Cl2). IR (KBr) n 1753,
1734 cm21 (CvO), 842 (C±Si). MS (m/z, rel. int.) 73(75),
92(29), 144(86), 170(67), 184(61), 193(35), 229(100),
302(48), 416(60), 429(16). 1H NMR (CDCl3, d ppm)
7.53±7.26 (m, 5H); 5.65±5.49 (m, 1H); 5.10±4.98 (m,
3H); 4.59 (t, 1H, J8.6 Hz); 4.35 (dd, 1H, J2.0 Hz,
J8.6 Hz); 3.59 (d, 1H, J6.4 Hz); 3.49 (d, 1H,
J6.5 Hz); 2.70 (s, 1H); 2.31 (dd, 1H, J8.5 Hz,
J14.2 Hz); 1.83 (dd, 1H, J6.1 Hz, J14.1 Hz); 0.13 (s,
9H); 0.11 (s, 9H). 13C NMR (CDCl3, d ppm) 164.4,
156.7, 140.1, 131.7, 129.0, 127.4, 119.9, 71.2, 70.3,
59.6, 52.9, 37.1, 36.4, 20.2, 20.3. Anal. calcd for
C22H34N2O3Si2 (430.56): C, 61.37; H, 7.97; N, 6.50.
Found: C, 61.55; H, 8.15; N, 6.23.
(3R)-1-[Bis(trimethylsilyl)methyl]-3-[(4-bromophenyl)-
methyl]-3-[(4S)-2-oxo-4-phenyloxazolidin-3-yl]azetidin-
2-one (17i). The general procedure was followed using
p-methylbenzyl bromide (5.00 g, 20 mmol) as the alkyl
halide. Yield 75%. Mp: 157±1588C (hexane).
[a]D25118.9 (c1.0, CH2Cl2). IR (KBr) n 1733 cm21
(CvO), 841 (C±Si). MS (m/z, rel. int.) 73(100), 91(7),
103(14), 104(26), 116(15), 357(18), 359(18). 1H NMR
(CDCl3, d ppm) 7.65±7.28 (m, 5H); 6.93 (d, 2H,
J8.3 Hz); 5.14 (dd, 1H, J1.7 Hz, J8.2 Hz); 4.63 (t,
1H, J8.2 Hz); 4.46 (dd, 1H, J1.4 Hz, J8.8 Hz); 3.50
(d, 1H, J6.7 Hz); 3.37 (d, 1H, J6.6 Hz); 2.80 (d, 1H,
J13.5 Hz); 2.49 (s, 1H); 2.32 (d, 1H, J13.5 Hz); 0.00
(s, 9H); 20.16 (s, 9H). 13C NMR (CDCl3, d ppm) 164.2,
156.7, 140.0, 133.8, 132.3, 131.7, 129.1, 127.7, 121.2, 71.7,
59.8, 52.3, 37.6, 36.7, 20.7, 20.6. Anal. calcd for
C26H35N2O3Si2Br (559.61): C, 55.80; H, 6.32; N, 5.00.
Found: C, 56.01; H, 6.25; N, 5.12.
(3R)-3-Benzyl-1-bis(trimethylsilyl)methyl-3-[(4S)-2-oxo-
4-phenyloxazolidin-3-yl]azetidin-2-one (17f). The general
procedure was followed using benzyl bromide (2.38 mL,
20 mmol) as the alkyl halide. Yield 90%. Mp: 168±1698C
(hexane). [a]2D5121.5 (c1.0, CH2Cl2). IR (KBr) n 1737,
1730 cm21 (CvO), 846 (C±Si). MS (m/z, rel. int.) 73(15),
93(11), 104(16), 144(22), 221(19), 235(24), 280(100),
1
466(15), 481(1.2). H NMR (CDCl3, d ppm) 7.70±7.17
(m, 10H); 5.18 (dd, 1H, J8.1 Hz, J1.8 Hz); 4.64 (t, 1H,
J8.5 Hz); 4.43 (dd, 1H, J8.7 Hz, J1.9 Hz); 3.52 (d, 1H,
J6.6 Hz); 3.44 (d, 1H, J6.4 Hz); 2.85 (d, 1H,
J13.7 Hz); 2.52 (s, 1H); 2.24 (d, 1H, J13.7 Hz); 0.00
(s, 9H); 20.12 (s, 9H). 13C NMR (CDCl3, d ppm) 164.0,
156.7, 140.1, 134.8, 130.5, 134.8, 130.5, 129.0, 128.5,
127.7, 126.9, 72.0, 71.1, 59.7, 52.1, 37.4, 37.2, 20.6.
Hydrogenation reaction of 17e: synthesis of (3R)-1-
bis(trimethylsilyl)methyl-3-[(4S)-2-oxo-4-phenyloxa-