Ethyl 3-amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxylate (IIa) was hydrolysed to the sodium salt of the corresponding acid (III) which upon treatment with acetic anhydride furnished the oxazinone derivativeIV. Recyclization ofIVwith ammonium acetate, hydrazine hydrate and/or aniline afforded the pyrimidine derivativesV, VIIIandXrespectively. Alkylation ofVgave the N-alkylated productsVIandVII. CompoundVIIIcondensed withp-nitrobenzaldehyde to give the Schiff baseIX. On the other hand, condensation of 3-amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydrothieno-[2,3-b]quinoline-2-carbonitrile (IIb) with triethyl ortho-formate gave methanimidate derivativeXIwhich reacted with hydrazine hydrate to yieldXII. Treatment ofXIIwith formic acid gave s-triazolo compoundXIII.3-Amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydro-thieno[2,3-b]quinoline-2-carboxamide (IIc) was also reacted with phenyl isothiocyanate, phenyl isocyanate, carbon disulfide and/or nitrous acid to afford the desired compoundsXVII, XIX, XXIandXXIIIrespectively. Alkylation ofXVII, XXIandXXIIIgaveXVIII, XXIIandXXIV–XXVI. Furthermore, the reaction products ofIIbandIIc. with acetic anhydride were identified.