Abstract
In this work 3-chloro-2-chlorocarbonylbenzo[b]thiophene (
1
) was prepared from cinnamic acid and then converted into the acid hydrazide
2
. The azomethines
3a-e
were prepared from the corresponding aryl aldehydes and the acid hydrazide
2.
Treatment of compound
2
with formic acid gave the N-formyl acid hydrazide
4
, which upon refluxing with phosphorous pentoxide or phosphorous pentasulphide in xylene yielded the corresponding 2- (3-chloro-1-benzothien-2-yl)-1,3,4-oxadiazole (
5
) and 2-(3-chloro-1-benzo-thien-2-yl)-1,3,4- thiadiazole (
6
). Reaction of
1
-thiosemicarbazide
7
with NaOH leads to ring closure giving 5- (3-chloro-1-benzothien-2- yl)-4H–triazole-3-thiol (
8
) which is converted into a number of derivatives
9-12
Reaction of
2
with phenyl isothiocyanate and NaOH afforded 5-(3-chloro- 1-benzothien-2-yl)-4-(phenyl)-4H-1,2,4-triazole-3-thiol (
14
).