Eine neue Synthese von 3‐Amino‐2‐acyl‐benzo[b]thiophenen

Abstract

Die 3-Chlor-1.2-benzisothiazoliumchloride 1 lassen sich mit Methylketonen 2 zu 3-Amino-2-acyl-benzo [b]thiophenen 3 umsetzen. Die neue Synthese ist weitgehend variierbar und lierfert einen bequemen Zugang zu dieser Stoffklasse. Die Verbindungen 3 lassen sich zu den Acylenaminen 5 desulfurieren, die wie 3 in der cis-s-cis-Konformation vorliegen. Weiter werden die Oxidation von 3 zu den Sulfonen 9, die Acylierung zu 4 und Umsetzungen mit Carbonylreagentien beschrieben. New Synthesis of 3-Amino-2-acylbenzo[b]thiophenesThe 3-chloro-l,2-benzisothiazolium chlorides 1 react with methyl ketones 2 to the 3-amino-2-acylbenzo[b]thiophenes 3. This new synthesis is extremely variable and offers a convenient preparative entry into this class of substances. The new 3-amino-2-acylbenzo[b]thiophenes 3 can be desulphurised to acylenamines 5 which are present in the cis-s-cis conformation. Further this report describes the oxidation of 3 to sulphones 9, the acylation of 3 to 4 and the reaction of 3 with carbonyl reagents. Kurzlich wurde von

Synthesis of 2-cyano, 2-acyl, and 2-carboxamido derivatives of 3-aminobenzo[b]thiophene involving nitro displacement

“…General Procedure for Aminobenzo[b Jthiophenes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11). To a mechanically stirred, cold solution (ice bath) containing 30 mmol of the substituted o-nitrobenzonitrile in 100 ml of DMF was added dropwise a solution containing 36 mmol of sodium sulfide (nonahydrate) in 20 ml of water.…”

“…Received June 14,1974 Until recently, 3-aminobenzo [6]thiophenes, substituted at the 2 position with cyano or acyl functions, were inaccessible. Clarke and coworkers1 reported the synthesis of 3-aminobenzo [6]thiophene-2-carbonitrile by the reaction of 0-mercaptobenzonitrile2 with chloroacetonitrile in aqueous alkali. Similarly prepared were 3-aminobenzo [b ] thien-2-yl methyl and phenyl ketones using chloroacetone and phenacyl chloride, respectively.…”

“…In situ alkylation with chloroacetonitrile, chloroacetone, or phenacyl chloride, with subsequent sulfide-catalyzed cyclization, yielded the corresponding 3aminobenzo[6 ]thiophene-2-carbonitriles, 3-aminobenzo-[6]thien-2-yl methyl ketones, or phenyl ketones, respectively. The procedure was also used as an alternate method of synthesis for 3-aminobenzo [6]thiophene-2-carboxam-ides8 when chloroacetamide was utilized as the alkylating agent. The derivatives prepared and the yields obtained are summarized in Table I.…”