Synthesis and Characterization of Substituted 4-Methoxy-1H-quinolin-2-thiones

Abstract

The synthesis of various substituted 4-methoxy-1H-quinolin-2-thiones from various substituted aniline with malonic acid, phosphorous-oxychloride, sodium methoxide glacial acetic acid and thiourea under different conditions is described. All these substituted 4-methoxy-1H-quinolin- 2-thiones were synthesized from four steps; the first step involved the synthesis of substituted 2,4-dichloro quinoline from aniline (substituted), with malonic acid and phosphorous-oxychloride. In the second step, the substituted 2,4-dichloro compound was heated with freshly prepared methanolic sodium methoxide solution to give 2,4-dimethoxy quinoline compounds, it was then refluxed with glacial acetic acid and hydrochloric acid to get the substituted 4-methoxy-1H-quinolin-2-one. The final steps involves with an objective of introducing a chloro in the position 2 of the quinolone system, the substituted 4-methoxy-1H-quinolin-2-one was refluxed with distilled PoCl₃ chloroform. The substituted 2-chloro-4-methoxy quinoline was then refluxed with thiourea and alcohol to get substituted 4-methoxy-1H-quinolin-2-thiones. The purity of the synthesized compound was judged by their C, H and N analysis and the structure was analyzed on the basics of mass, FT-IR and ¹H NMR.