Synthesis and Reactions of Some New 6,7-Dihaloquinolones Bearing Mercapto Groups

Reaction of the 6-chloro-7-fluoroquinoline 7 with methyl 2-mercaptoacetate, methyl 3-mercaptopropionate, or sodium thiophenolate furnished the quinolone derivatives of 3-carbonylsulfanyl-acetic acid methyl ester 8, the propionoate analogue 10, and 3-carbothioic acid S-phenyl ester 11 respectively. Ester 8 was converted into the 3-carbothioic acid S-carbamoyl derivative 9. Analogously, treatment of the 6,7-diflouroquinolone 12 with amino or mercapto precursors led to the formation of 13 and 14 respectively. Reaction of 14 with aqueous NH₃ or H₂O₂/AcOH afforded the acetamide 15 and the sulfoxide 16 analogues, respectively. The 5′-thioalkyl-acyclic quinolone nucleosides 19 and 20 were obtained from reaction of the mesylate derivative 18, prepared from the free nucleoside 17, with the methanthiolate and thiophenolate anions.