SYNTHESIS OF THIENOQUINOLINES: PART I. SYNTHESIS OF NOVEL HETEROCYCLO-THIENO[2,3-b]QUINOLINE DERIVATIVES

Abstract

Ethyl 3-amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxylate (II_a ) was hydrolysed to the sodium salt of the corresponding acid (III) which upon treatment with acetic anhydride furnished the oxazinone derivative IV. Recyclization of IV with ammonium acetate, hydrazine hydrate and/or aniline afforded the pyrimidine derivatives V, VIII and X respectively. Alkylation of V gave the N-alkylated products VI and VII. Compound VIII condensed with p-nitrobenzaldehyde to give the Schiff base IX. On the other hand, condensation of 3-amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydrothieno-[2,3-b]quinoline-2-carbonitrile (II_b ) with triethyl ortho-formate gave methanimidate derivative XI which reacted with hydrazine hydrate to yield XII. Treatment of XII with formic acid gave s-triazolo compound XIII.3-Amino-4-(p-chlorophenyl)-5,6,7,8-tetrahydro-thieno[2,3-b]quinoline-2-carboxamide (II_c ) was also reacted with phenyl isothiocyanate, phenyl isocyanate, carbon disulfide and/or nitrous acid to afford the desired compounds XVII, XIX, XXI and XXIII respectively. Alkylation of XVII, XXI and XXIII gave XVIII, XXII and XXIV–XXVI. Furthermore, the reaction products of II_b and II_c . with acetic anhydride were identified.

Key Words:

• Tetrahydroquinoline
• Thienoquinoline
• Thienoquinolinopyrimidine
• thienoquinolinotriazine.