Synthesis and reactions of thieno{[}2,3-b]quinoline derivatives

The synthesis of 3-amino-2-benzoylthieno{[}2,3-b]quinoline (2a) and 3-aminothieno{[}2,3-b]quinoline-2-carboxamide (2b) derivatives from 3-cyano-4-phenyl-8-methyl-5-(2-propenyl)-5,6-dihydro-2(3H)-quinolin-2-th ione (1) is described. Cyclocondensation of 2a with malononitrile, ethyl cyanoacetate, acetylacetone, ethylacetoacetate and diethyl malonate gave the corresponding pyridothieno{[}2,3-b]quinoline 3a-e. Treatment of 2b with formic acid or sodium nitrite afforded pyrimidinothienoquinoline 4 and triazinothienoquinoline 5 which were alkylated by methyl iodide to give 6 and 7 respectively. Reaction of 4-chloropyrimidinothienoquinoline 8 with some nucleophilic agents has been discussed.