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4642978 
Journal Article 
Synthesis of oxadiazoles, thiadiazoles and triazoles derived from benzo[b]thiophene 
Sharba, AH; Al-Bayati, RH; Aouad, M; Rezki, N 
2005 
1 
Molecules
ISSN: 1420-3049 
10 
9 
1161-1168 
English 
18007382 
WOS:000234297600013 
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).