4
XU ET AL.
2.7 | (3R,5R)-tert-Butyl-5-hydroxy-
(m, 1H), 1.42 (s, 9H); 13C NMR (100 MHz, CDCl3) δ
158.4, 140.4, 132.9, 128.7, 127.5, 98.2, 82.6, 60.7,
45.1, 28.1; Daicel CHIRALPAK OD-H column,
3-methylisoxazolidine-2-carboxylate (3g)9
29.6 mg, 73% yield, 43% ee; 1H NMR (400 MHz,
CDCl3) δ 5.69 (d, J = 8.0 Hz, 1H), 4.33-4.27 (m, 1H),
2.42-2.37 (m, 1H), 1.89-1.83 (m, 1H), 1.47 (s, 9H), 1.28
(d, J = 8.0 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ
158.7, 98.2, 81.9, 53.9, 43.2, 28.2, 21.5; Daicel
CHIRALPAK AD-H column, 220 nm, n-hexane/i-PrOH
= 96/4, 0.5 mL/min, major isomer: tR =12.6 minutes,
minor isomer: tR = 13.8 minutes.
220 nm, n-hexane/i-PrOH
major isomer: tR = 13.8 minutes, minor isomer: tR
12.6 minutes.
=
96/4, 0.5 mL/min,
=
2.11 | (3R,5R)-Benzyl-3-(2-bromophenyl)-
5-hydroxyisoxazolidine-2-carboxylate (3k)
37.7 mg, 50% yield, 54% ee; 1H NMR (400 MHz, CDCl3) δ
7.54 – 7.49 (m, 2H), 7.31-7.24 (m, 6H), 7.14-7.10 (m,1H),
5.87 (d, J = 4.0 Hz, 1H), 5.76 (t, J = 8.0 Hz, 1H), 5.19
(s, 2H), 3.06-3.00 (m, 1H), 2.13-2.07(m, 1H). 13C NMR
(100 MHz, CDCl3) δ 171.1, 159.0, 140.9, 135.5, 132.2,
128.8, 128.4, 128.1, 127.8, 126.8, 121.6, 98.8, 68.1, 61.2,
60.3, 44.4, 20.9, 14.1; Daicel CHIRALPAK OD-H column,
214 nm, n-hexane/i-PrOH = 94/6, 0.5 mL/min, major iso-
mer: tR = 9.5 minutes, minor isomer: tR = 10.3 minutes.
HRMS (ESI) C17H16NaBrNO4 (M+Na)+ calcd. 400.0155,
found 400.0160.
2.8 | (3R,5R)-tert-Butyl-5-hydroxy-
3-phenylisoxazolidine-2-carboxylate (3h)9
38.0 mg, 72% yield, 96% ee; 1H NMR (400 MHz,
CDCl3) δ 7.33 (d, J = 4.0 Hz, 4H), 7.28-7.24 (m, 1H),
5.90 (d, J = 4.0 Hz, 1H), 5.29 (t, J = 4.0 Hz, 1H),
2.79-2.74 (m, 1H), 2.31-2.25 (m, 1H), 1.42 (s, 9H); 13C
NMR (100 MHz, CDCl3) δ 158.6, 142.0, 128.5, 127.2,
126.1, 98.5, 82.4, 61.3, 45.3, 28.1; Daicel CHIRALPAK
OD-H column, 214 nm, n-hexane/i-PrOH = 94/6, 1.0
mL/min, major isomer: tR = 6.6 minutes, minor iso-
mer: tR = 8.3 minutes.
2.12 | (3R,5R)-tert-Butyl-3-(4-tolyl)-
5-hydroxyisoxazolidine-2-carboxylate (3l)
34.5 mg, 62% yield, 95% ee; 1H NMR (400 MHz, CDCl3) δ
7.19-7.14 (m, 2H), 7.07 (d, J = 8.0 Hz, 2H), 5.81 (d, J =
4.0 Hz, 1H), 5.18 (t, J = 8.0 Hz, 1H), 2.69-2.64 (m 1H),
2.26 (s, 3H), 2.22-2.17 (m, 1H), 1.35 (s, 9H). 13C NMR
(100 MHz, CDCl3) δ 158.7, 136.9, 129.2, 126.1, 98.5, 82.2,
61.1, 45.3, 28.1, 21.0; Daicel CHIRALPAK AD-H column,
254 nm, n-hexane/i-PrOH = 98/2, 1 mL/min, major iso-
mer: tR = 23.9 minutes, minor isomer: tR = 30.2 minutes.
HRMS (ESI) C15H21NaNO4 (M+Na)+ calcd.302.1363,
found 302.1361.
2.9 | (3R,5R)-tert-Butyl-
3-(2-bromophenyl)-5-hydroxyisoxazolidine-
2-carboxylate (3i)
1
38.4 mg, 56% yield, 61% ee; H NMR (400 MHz, CDCl3) δ
7.45 (d, J = 8.0 Hz, 2H), 7.23 (t, J = 10Hz, 1H), 7.07-7.03
(m, 1H), 5.81 (d, J = 4.0 Hz, 1H), 5.62 (t, J = 8.0 Hz, 1H),
2.93-2.88 (m, 1H), 2.02-1.96 (m, 1H), 1.36 (s, 9H). 13C NMR
(100 MHz, CDCl3) δ 158.3, 141.6, 132.5, 128.6, 127.8, 127.1,
121.7, 98.7, 82.5, 61.0, 44.5, 28.1; Daicel CHIRALPAK OD-
H column, 214 nm, n-hexane/i-PrOH = 98/2, 1.0 mL/min,
major isomer: tR
=
19.0 minutes, minor isomer:
2.13 | (3R,5R)-Benzyl-3-(furan-2-yl)-
tR = 20.9 minutes. HRMS (ESI) C14H18NaBrNO4 (M +
5-hydroxyisoxazolidine-2-carboxylate (3m)9
Na)+ calcd. 366.0311, found 366.0307.
39.3 mg, 68% yield, 54% ee; 1H NMR (400 MHz,
CDCl3)
δ 7.38 (s, 1H), 7.34-7.29 (m, 5H), 6.32
(s, 1H), 6.26 (s, 1H), 5.87 (d, J = 9.0 Hz, 1H), 5.45
(t, J = 8 Hz, 1H), 5.22 (s, 2H), 2.64-2.56 (m, 2H). 13C
NMR (100 MHz, CDCl3) δ 159.3, 152.4, 142.5, 135.6,
128.5, 128.3, 128.0, 110.3, 107.3, 98.7, 68.3, 60.3, 55.1,
40.5, 21.0, 14.1; Daicel CHIRALPAK AD-H column,
2.10 | (3R,5R)-tert-Butyl-
3-(4-chlorophenyl)-5-hydroxyisoxazolidine-
2-carboxylate (3j)9
41.8 mg, 70% yield, 44% ee; 1H NMR (400 MHz,
CDCl3) δ 7.32-7.26 (m, 4H), 5.86 (d, J = 4.0 Hz, 1H),
5.25 (t, J = 4.0 Hz, 1H), 2.78-2.73 (m, 1H), 2.25-2.19
254 nm, n-hexane/i-PrOH
=
97/3,
1
mL/min,
major isomer: tR = 14.5 minutes, minor isomer:
tR = 17.0 minutes.