Chemistry Reference
In-Depth Information
Piperacillin [61477-96-1], antibiotic, 201.
Phosgenation of 2,3-dioxo-1-ethyl-piper-
azine 197 gives the corresponding carbamoyl chloride 198 through the intermedi-
ate trimethylsilyl derivative 200 [146]. 4-Ethyl-2,3-dioxo-1-piperazinecarbonyl chlo-
ride 198 condenses with Ampicillin 199 to form Piperacillin [147-151]. The same
carbamoyl chloride is used for the preparation of Cefoperazone [62893-19-0], an-
other antibiotic.
COOH
O
O
O
1. dioxane, Me
3
SiCl, NEt
3
2.
COCl
2
, THF
N
O
O
N
O
N
H
2
N
S
N
Cl
N
H
H
NH
O
198
199
197
NEt
3
pH 8, 0-5°C
O
O
COCl
2
-Me
3
SiCl
N
N
O
COOH
SiMe
3
O
O
N
200
N
O
H
N
N
S
N
H
H
O
201
Piperacillin
In one method, phosgene is
Pyridoxine [65-23-6], vitamin (enzyme co-factor), 205.
employed to cyclize the oxalic amide 202 [152].
O
O
H
N
N
COCl
2
NEt
3
O
O
O
O
O
O
O
202
203
N
1. NaOH
2. HCl
HO
OH
O
3.
O
OH
204
205
Pyridoxine
Quetiapine fumarate [111974-72-2], antipsychotic, 209.
In one method, phosgene is
employed to generate o-isocyanato diphenyl sulfide 207, which is converted into 11-
