Chemistry Reference
In-Depth Information
12:7:1) of the residue gave a single fraction containing the diastereomeric oxazo-
lidones 698 as a 1:1 cis/trans mixture, obtained as a clear, colorless oil (17.6 mg,
55%).
O
CH
3
NH
2
*HCl
O
CDI
, THF/DMF, 0°C
H''
CH
3
HN
OH
H'
CH
3
CH
3
699 a
700 a
H':
d
= 3.9 ppm
H":
d
= 4.6 ppm
J
H',H"
= 10.6 Hz
O
CH
3
NH
2
*HCl
O
CDI
, THF/DMF, 0°C
H''
CH
3
HN
OH
H'
CH
3
CH
3
699 b
700 b
H':
d
= 3.58, 3.66 ppm
H":
d
= 4.16, 4.28 ppm
J
H',H"
= 8.5, 5.9 Hz
Typical procedure for the synthesis of cyclic carbamates 700a,b [464]:
To a solution of
(2S,3S,4R)-2-amino-4-phenyl-3-pentanol 699a and (2S,3S,4S)-2-amino-4-phenyl-3-
pentanol 699b (70 mg, 0.47 mmol) in THF/DMF (3:1; 4 mL) at 0
C was added
CDI (175 mg, 1.08 mmol). The reaction vessel was flushed with nitrogen, stop-
pered, and the contents were stirred for 14 h at 0
C. Water (4 mL) was added to
the suspension and the mixture was extracted with EtOAc (3
5 mL). The com-
bined organic layers were washed with brine (10 mL), dried, and concentrated to
an oil, which was chromatographed (radial chromatography) with a gradient of
25-50% EtOAc in hexane as eluent. Concentration of the collected fraction yielded
40 mg (50%) of 700b as a 2:1 mixture of diastereomers; TLC (EtOAc/hexane, 3:1):
R
f
39. Carbamate 700a was prepared in a similar manner and purified on a
plate of silica gel (100
¼
0
:
m
m thickness); R
f
¼
0
:
35.
TBDMS
TBDMS
TBDMS
O
O
O
CDI,
DMAP, THF
15 h, rt
H
2
N
HN
H
2
N
O
OH
O
O
85 %
701
702
703
