Synthesis of [1]Benzothieno[2,3-b]quinolines via Transition-Metal-Free [3+3] Annulation of Nitroarenes and Benzo[b]thiophen-3-ylacetonitrile or 3-(Phenylsulfonylmethyl)benzo[b]thiophene Carbanions

Abstract

Benzo[b]thiophen-3-ylacetonitriles or 3-(phenylsulfonylmethyl)benzo[b]thiophenes react with nitrobenzene derivatives in the presence of potassium tert-butoxide and chlorotrimethylsilane to form, in good yields, 11-cyano- or 11-(phenylsulfonyl)[1]benzothieno[2,3-b]quinolines, respectively.

Synthesis and reactivity of thieno[2,3‐b]quinoline derivatives (Part II)

“…Wojciechowski and Nowacki carried out the reaction of 3‐(cyanomethyl)benzo[ b ]thiophene 130a or 3‐((phenylsulfonyl)‐methyl)benzo[ b ]thiophene 130b with nitrobenzenes 134 in THF in the presence of potassium tert ‐butoxide and triethylamine at −70°C, then added chlorotrimethylsilane at this temperature, and stirred the reaction mixture for 3 hours. The reaction mixture was allowed to reach room temperature and stirred overnight, then the reaction mixture was quenched with saturated aqueous ammonium chloride to give the benzothieno[2,3‐ b ]quinolines 135 (Scheme 33) [68].…”

“…Nucleophilic substitution reaction of the phenylsulfonyl group of 135 with alkylamine, cyclohexylamine, butylamine and 2‐aminopropane 136a–c in THF give the corresponding 11‐(alkylamino)[1]‐benzothieno[2,3‐ b ]quinoline 137a–c (Scheme 34) [68].…”