Convenient and Efficient Synthesis of 11‐Amino‐2,8‐substituted‐2,3,8,9‐tetrahydrobenzo[4,5]thieno [2,3‐b]quinolinone Derivatives.

The Gewald reactions of 5-substituted-1,3-cyclohexanedione, malononitrile, and powdered sulfur were carried out to give the corresponding products 2-amino-5-substituted-7-oxo-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile derivatives 1. The intermediate enamines 2 were prepared by reaction of compounds 1 and 5-substituted-1,3-cyclohexanedione with hydrochloric acid as catalyst. The title compounds 11-amino-2,8-substituted-2,3,8,9-tetrahydrobenzo[4,5]thieno[2,3-b]quinolinone 3 were synthesized by cyclization of compounds 2 in the presence of K2CO3 and Cu2Cl2. The structures of all compounds were characterized by elemental analysis, IR, MS, and 1H-NMR spectra.