合成路线1

Thiol (II) was prepared by reduction of 4-ethylbenzenesulfonyl chloride (I) with LiAlH4. Subsequent alkylation of (II) with ethyl 4-chloroacetoacetate (III) provided sulfide (IV), which was cyclized to the required benzothiophene (V) on heating with polyphosphoric acid in toluene. Basic hydrolysis of the ester group of (V) gave carboxylic acid (IV). After conversion of (VI) to the corresponding acid chloride with SOCl2, treatment with NH4OH yielded amide (VII). This was dehydrated to nitrile (VIII) using trifluoroacetic anhydride and triethylamine. Reduction of the nitrile function of (VIII) by means of LiAlH4 and AlCl3 gave rise to the corresponding primary amine, which was isolated as the hydrochloride salt (IX). Finally, acylation with acetyl chloride furnished the title acetamide.