| abstract |
Pyrido-benzothiazine compounds having anti-microbial activity are prepared by (a) reacting 3-chloro-4-fluoroaniline with potassium thiocyanate and bromine to produce 2-amino-6-fluoro-7-chlorobenzothiazole, (b) reacting 2-amino-6-fluoro-7-chlorobenzothiazole with sodium hydroxide to produce the disulfide of 2-amino-5-fluoro 6-chlorothiophenol, (c) reacting the disulfide with sodium monochloroacetate to produce 7-fluoro-8-chloro-2H-1,4-benzothiazin-3(4H)-one, (d) reducing 7-fluoro-8-chloro-2H-1,4-benzothiazin-3(4H)-one to produce 7-fluoro-8-chloro-3,4-dihydro-2H-1,4-benzothiazone, (e) reacting 7-fluoro-8-chloro-3,4-dihydro-2-H-1,4-benzothiazone with ethyl ethoxymethylenemalonate and cyclyzing the intermediate formed with polyphosphoric acid to produce ethyl 9-fluoro-10-chloro-7-oxo-2,3-dihydro-7H-pyrido[1,2,3 de] [1,4]-benzothiazine-6-carboxylate and (f) hydrolyizing the ethyl carboxylate to produce the corresponding carboxylic acid. |