Antimycobacterial Activity of Some Synthesized Compounds
831
C6H5
NH2
N
Br /HAC
N
O
KSCN;
NH3
2
+
F
O
NH2
S
F
H1C
C6H5
Cl
Cl
2
Oxazolone
1
6 Hrs. reflux in pyridine
C6H5
N
N
C6H5
N
N
S
N
F
S
N
CH
C6H5
R
F
O
CH
C6H5
Cl
O
3
4 (a-i)
Experimental
Purity of compounds was checked by TLC. Melting points were determined by open
capillaries method and uncorrected. IR spectra (NaCl) are recorded on FTIR (Schimadzu-
8300) spectrophotometer using nujol mull technique. For antimycobacterial activity in vitro
by tube dilution technique using the human virulent H37RV strains of M. tuberculosis.
General Procedure
2-Amino-6-fluoro-7-chloro-(1,3)benzothiazole (1)
To the glacial acetic acid (20 mL) which is cooled below room temperature, 8 g (0.08 mol)
of potassium thiocyanate and 1.45 g (0.01 mol) of fluorochloroaniline was added. The
mixture was placed in freezing mixture of ice and salt, mechanically stirred while 1.6 mL of
bromine in 6 mL of glacial acetic acid was added, from a dropping funnel at such a rate that
the temperature never rose beyond room temperature. After all the bromine was added
(105 min), the solution was stirred for 2 h below room temperature and at room temperature
for 10 h, it was then allowed to stand over night, during which period an orange precipitate
0
settle at the bottom, water (6 mL) was added quickly and slurry was heated at 85 C on a
steam bath and filtered hot. The orange residue was placed in a reaction flask and treated
0
with 10 mL of glacial acetic acid heated again to 85 C and filtered hot. The combined
filtrate was cooled and neutralized with concentrated ammonia solution to pH 6. A dark
yellow precipitate was collected. Recrystallised from benzene-ethanol mixture (1:1) after
treatment with animal charcoal gave yellow plates of 2-amino-6-fluoro-7-chloro-(1,3)
benzothiazole. After drying in an oven at 80 0C, the dry material (1 g 51.02%) melted at 210-
0
212 C. UV 307.4, 269 nm, IR 1542 cm-1 (aromatic C=C) and 3475 cm-1 (NH2); 1456 cm-1
(thiazole), 1215 cm-1 (aromatic-F), 712 cm-1 (aromatic-Cl).
2-Phenyl- 4-benzylidine-5-oxazol-5-one (oxazolone) (2)
Redistilled benzaldehyde was treated with benzoyl glycine (Hippuric acid) in presence of
acetic anhydride (dry acetic acid) and anhydrous sodium acetate to get 4-benzylidene-2-
phenyl-oxazol-5-one(oxazolone). Upon washing with ice cold alcohol and then with boiling
0
water (Yield 80%), melted at 165-166 C, IR (NaCl) 1790 cm-1 (Lactone carbonyl) and
another bond at 1650 cm-1(C=N stretching).
2[2’- Phenyl -4’- benzidinyl- 5’- oxo- imidazoline- 1yl- amino] -6 fluoro- 7- chloro
(1,3) benzothiazoles (3)
A mixture of 0.01 mol. of 2-amino-6-fluoro-7-chloro-(1,3)benzothiazole (1) with 2-phenyl-
4-benzylidine-5-oxazol-5-one (oxazolone)(2) refluxed in pyridine for 6-8 hours. Excess of
Sathe
