Chemistry Reference
In-Depth Information
afforded first 681 (0.07 g, 63%) as a syrup and then 682 (0.03 g, 27%) contaminated
by a small amount of 681.
4-Benzyloxymethyl- and 4-benzyl-5-thiazol-2-yl-oxazolidin-2-one (685 and 686)
have been prepared with 1,1-carbonyldiimidazole from deprotected amino alcohols
684 [453].
O
O
Boc
N
H
N
N
H
2
N
HN
HN
CDI
O
O
S
+
R
S
R
THF, 5 h
R
R
OH
OH
N
N
S
S
683
684
685a,
J
4,5
= 8.5 Hz
686a
, J
4,5
= 8.05 Hz
685b,
J
4,5
= 4.9 Hz
686 b
, J
4,5
= 4.9 Hz
R = -CH
2
OBn
R = Bn
R = -CH
2
OBn
R = Bn
General procedure. Oxazolidinones 685 and 686 [453]:
To a stirred mixture of the
amino alcohols 683 in dichloromethane (0.52 mmol) was added trifluoroacetic
acid/water (95:5; 2 mL). After stirring for 1 h, the trifluoroacetic acid was evapo-
rated in vacuo. The residue was dissolved in ethyl acetate (10 mL), and saturated
aq. NaHCO
3
solution (5 mL) was added. After extraction with ethyl acetate (3
10
mL), the combined organic layers were dried (Na
2
SO
4
), and the solvent was
evaporated in vacuo. The deprotected amino alcohol 684 thus obtained was redis-
solved in THF (5 mL) and treated with a solution of CDI (1.06 g, 0.66 mmol) in the
same solvent (3 mL). After stirring for 4-5 h, the reaction mixture was concen-
trated in vacuo, and saturated aq. NaHCO
3
solution was added. After extraction
with ethyl acetate (3
15 mL), the combined organic layers were dried (Na
2
SO
4
)
and the solvent was evaporated under reduced pressure.
1
H NMR analysis of the
residue revealed the syn/anti diastereomeric ratio of the amino alcohols obtained.
Chromatography (silica gel; diethyl ether/petroleum ether, 95:5) of the oxazo-
lidinone mixture derived from 684 (R
CH
2
OBn) (ds
syn
80% in CH
2
Cl
2
) gave the
threo isomer 685b (0.113 g, 75%) and the erythro isomer 685a (0.031 g, 20%).
Chromatography (silica gel; petroleum ether/ethyl acetate, 8:2) of the mixture
derived from 684 (R
¼
Bn) (ds
syn
80% in CH
2
Cl
2
) gave a mixture of the oxazo-
lidinones 686a and 686b (96%).
¼
O
HN
O
CDI
O
3
H
2
N
O
3
CH
2
Cl
2
, 0-24 °C
OH
O
O
687
688
(4S,5S)
