Chemistry Reference
In-Depth Information
COOH
COOH
1. CbzoCl, NaOH
HN
NH
2
* 2 HCl
2. H
+
N
Cbzo
N
1192
1193
PCl
5
X
COCl
2
O
O
H
N
N
O
* HCl
1194
Typical procedure. 4-(3-Pyridylmethyl)oxazolidine-2,5-dione hydrochloride 1194 [877]:
A
suspension of triply recrystallized a,N-carbobenzoxy-b-(3-pyridyl)-dl-alanine 1193
(2.92 g, 9.7 mmol) in dry dioxane (50 mL) was treated, in a drybox and with rapid
stirring, with a solution of PCl
5
(3.06 g, 14.7 mmol) in dioxane (125 mL). After a
few minutes, a clear solution was transiently formed, which then became cloudy
once more. After about 2 h, precipitation began. After about 6 h, the precipitate
was collected by filtration, stirred overnight with dry diethyl ether or chloroform to
remove occluded PCl
5
, filtered once more, and dried to yield 2.05 g (92.4%) of 4-(3-
pyridylmethyl)oxazolidine-2,5-dione hydrochloride 1194.
The synthetically available di-Z-meso-2,2
0
-diaminopimelic acid 1195 was treated
with PCl
5
(2.2 equiv.) in dichloromethane (0
C
!
reflux, 1 h) to form the crystal-
line bis(N-carboxy anhydride) 1196 [878-880].
O
O
L
L
O
H
N
ZHN
CHCOOH
(CH
2
)
3
CHCOOH
PCl
5
CH
2
Cl
2
(CH
2
)
3
ZHN
O
H
N
D
D
O
O
1195
1196
Chloroformates
Amino-diphenyl-acetic acid 1197 was cyclized to 4,4-diphenyl-oxazolidine-2,5-dione
1198 with ethyl chloroformate in aqueous sodium hydroxide solution [881].
O
O
Ph
Ph
EtOCOCl
O
H
2
N
OH
N
H
Ph
Ph
O
1197
1198
