5- Chloro-2-methylbenzo thiophene

The corresponding bis(benzothienyl)perhydrocyclopentene 131, which was synthesized from 5-chloro-2-methylbenzo[b]thiophene similarly to dithienylcyclopentenes, was subjected to subsequent modifications due to the presence of chlorine atoms in the benzene ring (07MC125) (Scheme 41). 

Additional examples of syntheses of polycyclic triazoles continue to be reported. 2-(2 -Hydroxyphenyl)benzotriazole (84) is prepared in >90% yield from azointermediate (83) by reaction with Raney nickel and DMSO, DMS or thiophene [95JAP07228577]. 2-Methylbenzo-triazole (85) is cyclized under acidic conditions and subsequently converted into the chloro analog (86) by treatment with POCl3 [95FES47],... 

Most recent publications on the sulfonation of benzo[h]thiophenes confirm existing knowledge.1,2 Benzo[b]thiophene and its 5-bromo and 7-chloro derivatives undergo sulfonation (H2S04-Ac20) in the 3-position.550 3-Methylbenzo[b]thiophene 1,1-dioxide is chlorosulfonated in the 2-position551 the apparent absence of substitution in the 6-position is unusual for a 1,1-dioxide. 

CAS 2379-74-0 EINECS/ELINCS 219-163-6 Synonyms 6-Chloro-2-(6-chloro-4-methyl-3-oxobenzo [b] thien-2(3H)-ylidene)-4-methylbenzo [b] thiophen-3(2H)-one Vat red 1... 

The synthesis of nonsymmetric cyclopentenes, containing both thien-3-yl and benzo[Z7]thien-3-yl units, was aimed at more sophisticated photochromic molecules (Scheme 54) [73]. By the application of glutaric anhydride with 2-chloro-5-methylthiophene and 5-bromo-2-methylbenzo[h]thiophene in the presence of AICI3, keto acids 52 and 53 were obtained. Conversion of the keto acids into acid anhydrides then Friedel-Crafts acylations produced the desired diketone albeit in only 31% yield (over 2 steps) in the first case and in 14% yield (over two steps) in the second case (Scheme 54) [73]. 

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