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Matsuki, Yasuo; KANDA, Tatsuo

doi:10.1246/nikkashi1948.86.637

Cited by 3 publications

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“…Acetylation of 5-methylbenzo [b]thiophene gives a mixture of the 2-and 3-ketone derivatives in which the 3-isomer predominates [6]. A very similar mixture of isomers is obtained when the starting material is benzo [b]thiophene itself [7].…”

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Synthesis of new 5‐substitutedbenzo[b]thiophene derivatives

Pérez‐Silanes¹,

Martínez-Esparza²,

Oficialdegui³

et al. 2001

Journal of Heterocyclic Chem

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Previous works of our group have dealt with the synthesis of 1-(aryl)-3-[4-(aryl)piperazin-1-yl]propane derivatives in the search for new and efficient antidepressants with a dual mode of action: serotonin reuptake inhibition and 5-HT 1A receptor afinity [1][2][3][4]. From these studies we concluded that the 3-[4-(aryl)piperazin-1-yl]-1-(benzo [b]thiophen-3-yl)propane derivatives led to the best results. The continuation of this research project required the preparation of some new 3-acyl-5-substituted benzo [b]thiophenes with a wide variety of substituents at the 5 position, ranging from nitro to hydroxyl derivatives. To obtain these derivatives we acylated the corresponding 5-substituted benzo [b]thiophenes when it was possible. In this paper we describe the synthesis of 3-acyl-5-substitutedbenzo[b]thiophenes by Friedel-Crafts acylation of 5-substitutedbenzo [b]thiophenes. The starting compounds for the acylating reactions were synthesized according to described methods, which in most cases, were modified in order to optimize the yields and to facilitate the isolation of the product. 5-Nitrobenzo[b]thiophene was synthesized according to the literature [8,9], with slight modifications. In the first step, 5-nitro-2-chlorobenzaldehyde was treated with sodium sulfide nonahydrate and ethyl bromoacetate in basic medium, yielding ethyl 5-nitrobenzo[b]thiophene-2-carboxylate 1 (Scheme 1). Alkaline hydrolysis of this compound gave the corresponding acid 2, which was decarboxylated in copper-quinoline to 5-nitrobenzo[b]-thiophene 3 following described methods [8].

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confidence: 98%