Solantal,Fujisawa,Japan,1975
A solution of ethyl 5-chloro-2-oxo-3-benzo-thiazolineacetate (4.0 grams) in 1-
(2-hydroxyethyl)piperazine is heated at 100°C for 24 hours. After cooling, the
resulting mixture is extracted with chloroform. The chloroform extract is
washed with water and shaken with 10% hydrochloric acid. The hydrochloric
acid layer is washed with chloroform, made alkaline with 10% sodium
hydroxide solution and extracted with chloroform. The chloroform extract is
washed with water, dried over magnesium sulfate and concentrated. The
residual oil (5.5 grams) is allowed to stand to form crystals, which are
recrystallized from a mixture of ethyl acetate (40 ml) and ethanol (15 ml) to
give 3-[4-(2-hydroxyethyl)-1-piperazinylcarbonylmethyl]-5-chloro-2(3H)-
benzothiazolinone (3.2 grams) as colorless crystals, MP 159° to 161°C.
The following is an alternate method of preparation: A mixture of 3-(1-
piperazinyl)carbonylmethyl-5-chloro-2(3H)-benzothiazolinone (500 mg),
anhydrous potassium carbonate (400 mg), 2-hydroxyethyl bromide (300 mg)
and anhydrous ethanol (20 ml) is heated while refluxing for 5 hours. The
reaction mixture is concentrated under reduced pressure. The residue is
extracted with chloroform. The chloroform layer is dried over magnesium
sulfate and concentrated. The residue is crystallized from a mixture of ethyl
acetate and ethanol to give 3-[4-(2-hydroxyethyl]-1-
piperazinylcarbonylmethyl]-5-chloro-2(3H)-benzothiazolinone (370 mg) as
crystals, MP 159° to 160°C.
