Claudia Neri, Jonathan M. J. Williams
FULL PAPERS
1780, 1735, 1695, 1450, 1370, 1225, 1110 cmÀ1; 1H NMR
(300 MHz, CDCl3): d 7.36 7.19 (5H, m, C6H5), 5.30 (1H,
dq, J 4.3 and 6.4 Hz, CHOCOCH3), 4.64 4.56 (1H, m,
(100), 69 (29), 43 (50); anal. calcd. for C18H23NO5: C 64.85%, H
6.95%, N 4.20%; found: C 64.7%, H 7.0%, N 4.0%.
NCH), 4.28 4.08 (2H, m, CH2O), 3.95 (1H, dq, J 4.3 and
6.9 Hz, COCHCH3), 3.27(1H, dd, J 3.1 and 13.2 Hz,
CHHPh), 2.76 (1H, dd, J 9.7and 13.3 Hz, C HHPh), 2.05
(3H, s, OCOCH3), 1.28 (3H, d, J 6.5 Hz, COCHCH3),1.22
(3H, d, J 6.9 Hz, AcOCHCH3); 13C NMR (75.5 MHz,
CDCl3): dC 172.2 (CCO), 151.7(O CON), 168.8 (OCOCH3),
(2C), 127.1 (2C), 125.5 (aromatic C), 68.4 (CHOCOCH3), 64.5
(CH2O), 54.0 (NCH), 40.5 (COCHCH3), 36.1 (CH2Ph), 19.3
(OCOCH3), 16.2 (AcOCHCH3), 8.9 (COCHCH3); MS (EI ,
(4R,2'R,3'S)-N-(3-Hydroxy-2-ethylbutanoyl)-4-benzyl-
2-oxazolidinone (4R,2'R,3'S)-15
Alcohol (4R,2'R,3'S)-15 was isolated as a cream solid (30%);
mp 73 748C (Lit.[40] 74 768C); Rf (n-hexane/EtOAc,
¾
50:50) 0.55; HPLC (Chiralcel OD column, n-hexane/2-
propanol, 90:10, 1 mL minÀ1, l 254 nm): tR 14.6 min;
[a]D30: À 15.8 (c 1.2, CHCl3); IR (CH2Cl2): n 3590, 2980,
1
1780, 1690, 1385, 1350, 1215, 1110 cmÀ1; H NMR (300 MHz,
7 0 eV):m/z 319 (M , 10%), 259 (57), 244 (46), 178 (30), 83
(95), 43 (100); HRMS (EI ): calcd. for C17H21NO5: 319.1420;
found: 319.1417; anal. calcd. for C17H21NO5: C 63.93%, H
6.62%, N 4.38%; found: C 63.5%, H 6.6%, N 4.2%.
CDCl3): d 7.37 7.22 (5H, m, C6H5), 4.78 4.70 (1H, m,
NCH), 4.22 4.07(3H, m, C H2O, CHOH), 4.03 3.97(1H, m,
CHCH2CH3), 3.36 (1H, dd, J 3.2 and 13.2 Hz, CHHPh), 2.70
(1H, dd, J 10.0 and 13.2 Hz, CHHPh), 2.54 (1H, s, OH),
1.91 1.83 (1H, m, CHHCH3), 1.74 1.66 (1H, m, CHHCH3),
1.24 (3H, d, J 7.0 Hz, CHCH3), 0.98 (3H, t, J 7.4 Hz,
CH2CH3); 13C NMR (75.5 MHz, CDCl3): d 175.5 (CCO),
153.9 (OCON), 135.2, 129.4 (2C), 129.0 (2C), 127.4 (aromatic
C), 68.6 (CHOH), 66.0 (CH2O), 55.6 (CHN), 50.1
(CHCH2CH3), 38.1 (CH2Ph), 20.7( CH2CH3), 19.5 (CHCH3),
11.9 (CH2CH3); MS (EI , 7 0 eV):m/z 291 (M¥, 11%), 158
(26), 128 (27), 99 (100), 86 (67), 71 (77), 53 (33), 43 (90); anal.
calcd. for C16H21NO4: C 65.96%, H 7.27%, N 4.81%; found: C
65.6%, H 7.2%, N 4.6%.
(4R,2'R,3'S)-N-(3-Hydroxy-2-methylbutanoyl)-4-
benzyl-2-oxazolidinone (4R,2'R,3'S)-10
Colourless crystals (39% in hexane); mp 114 1158C; Rf (n-
¾
hexane/EtOAc, 50:50) 0.37; HPLC (Chiralcel OD column,
n-hexane/2-propanol, 80:20, 1 mL minÀ1, l 254 nm): tR
1
10.0 min; [a]D30: À 54.5 (c 0.99, CHCl3); H NMR (400 MHz,
CDCl3): d 7.36 7.20 (5H, m, C6H5), 4.74 4.67 (1H, m,
NCH), 4.26 4.10 (3H, m, CHCH2O, CHOH), 3.74 (1H, dq,
J 2.7and .70 Hz, COC HCH3), 3.25 (1H, dd, J 3.5 and
13.2 Hz, CHHPh), 2.91 (1H, d, J 2.7Hz, O H), 2.79 (1H, dd,
J 9.7and 13.4 Hz, C HHPh), 1.27(3H, d,
J 7.0 Hz,
(4S,2'S,3'R)-N-(3-Acetoxy-2-methylbutanoyl)-4-ethyl-
2-oxazolidinone (4S,2'S,3'R)-22
COCHCH3), 1.21 (3H, d, J 6.2 Hz, CHOHCH3); 13C NMR
(75.5 MHz, CDCl3): d 178.0 (CCO), 153.7(O CON), 135.6,
130.0 (2C), 129.6 (2C), 128.0 (aromatic C), 68.2 (CHOH), 66.8
(CH2O), 55.7( CHN), 43.7(CO CHCH3), 38.4 (CH2Ph), 20.1
(CHOHCH3), 11.1 (COCHCH3); MS (FAB , 7 0 eV):m/z
Ester (4S,2'S,3'R)-22 was isolated as a yellow oil (33%); HPLC
¾
(Chiralcel
OD column, n-hexane/2-propanol 80:20,
1 mL minÀ1, l 254): tR 6.0; [a]D30: À 86.6 (c 0.30, CHCl3);
IR (film): n 2985, 2940, 1780, 1735, 1385, 1370, 1700, 1240,
1210 cmÀ1; 1H NMR (300 MHz, CDCl3): dH 5.27(1H, dq, J
3.2 and 6.4 Hz, CHOCOCH3), 4.44 4.35 (2H, m, CHN,
OCHH), 4.13 (1H, dd, J 1.8 and 8.0 Hz, OCHH), 3.96 (1H,
dq, J 3.4 and 6.9 Hz, COCHCH3), 2.02 (3H, s, OCOCH3),
278 (M 1, 100%), 261 (9), 178 (25), 117 (10), 101 (7); HRMS
(FAB ): calcd. for C15H19NO4: 277.1314; found: 277.1314;
anal. calcd. for C15H19NO4: C 64.97%, H 6.91%, N 5.05%;
found: C 64.3%, H 6.9%, N 5.1%.
1.82 1.72 (2H, m, CH2CH3), 1.26 (3H, d, J
6.4 Hz,
COCHCH3), 1.19 (3H, d, J 6.9 Hz, AcOCHCH3), 0.92 (3H,
t, J 7.5 Hz, CH2CH3); 13C NMR (75.5 MHz, CDCl3): d
174.0 (CCO), 170.6 (OCOCH3), 153.8 (OCON), 70.3 (CHOC-
OCH3), 66.8 (CH2O), 55.6 (CHN), 42.1 (COCHCH3), 25.1
(CH2CH3), 21.1 (OCOCH3), 18.1 (AcOCHCH3), 11.0
(COCHCH3), 8.2 (CH2CH3); MS (CI , 7 0 eV):m/z 258
(4S,2'S,3'R)-N-(3-Acetoxy-2-ethylbutanoyl)-4-benzyl-
2-oxazolidinone (4S,2'S,3'R)-16
Ester (4S,2'S,3'R)-16 was isolated as a cream solid (35%);
recrystallised from n-hexane/EtOAc; mp 61 638C; Rf (n-
¾
hexane/EtOAc, 50:50) 0.85; HPLC (Chiralcel OD column,
n-hexane/2-propanol, 90:10, 1 mL minÀ1, l 254 nm): tR
11.5 min; [a]D30: 57.1 (c 1.05, CHCl3); IR (CH2Cl2): n 2965,
(M 1, 55%), 198 (100), 171 (12), 143 (21), 83 (40); anal. calcd.
for C12H19NO5 : C 56.02%, H 7.44%, N 5.44%; found C 55.6%,
H 7.5%, N 5.4%.
1
1780, 1730, 1695, 1380, 1235, 1110 cmÀ1; H NMR (300 MHz,
CDCl3): d 7.36 7.21 (5H, m, C6H5), 5.30 5.22 (1H, m,
CHCH3), 4.72 4.64 (1H, m, NCH), 4.24 4.10 (2H, m, CH2O),
4.04 3.98 (1H, m, CHCH2CH3), 3.32 (1H, dd, J 3.2 and
13.2 Hz, CHHPh), 2.73 (1H, dd, J 9.9 and 13.2 Hz, CHHPh),
2.01 (3H, s, OCOCH3), 1.91 1.83 (1H, m, CHHCH3), 1.74
1.66 (1H, m, CHHCH3), 1.27(3H, d, J 6.7Hz, CHC H3), 0.95
(3H, t, J 7.4 Hz, CH2CH3); 13C NMR (75.5 MHz, CDCl3):
d 173.3 (CCO), 170.4 OCOCH3), 153.4 (OCON), 135.3,
129.4 (2C), 128.9 (2C), 127.3 (aromatic C), 70.1 (CHCH3), 66.1
(CH2O), 55.7( CHN), 48.6 (CHCH2CH3), 38.1 (CH2Ph), 21.1
(4R,2'R,3'S)-N-(3-Hydroxy-2-methylbutanoyl)-4-
ethyl-2-oxazolidinone (4R,2'R,3'S)-21
Unreacted alcohol (4R,2'R,3'S)-21 was obtained as a colour-
less oil (36%); Rf (n-hexane/EtOAc, 40:60) 0.53; HPLC
¾
(Chiralcel
OD column, n-hexane/2-propanol 80:20,
1 mL minÀ1, l 254): tR 7.3 min; [a]D30: À 40.0 (c 0.35,
1
CHCl3); H NMR (300 MHz, CDCl3): dH 4.50 4.45 (1H,
(OCOCH3), 20.0 (CH2CH3), 17.7 (CHCH3), 11.7(CH CH3);
m, CHN), 4.40 (1H, app. t, J 8.5 Hz, OCHH), 4.17 4.10 (2H,
2
MS (EI , 7 0 eV):m/z 333 (M , 30%), 258 (20), 157(32), 97
m, OCHH, CHOH), 3.71 (1H, dq, J 3.5 and 7.1 Hz,
846
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2003, 345, 835 848