Quinolonecarboxylic Acids. 2. Synthesis and Antibacterial Evaluation of 7-Oxo-2,3-dihydro-7H-pyridobenzothiazine-6-carboxylic Acids

Article abstract of DOI:10.1021/jm00386a005

A series of pyridobenzothiazine acid derivatives was synthesized and their in vitro antibacterial activity was evaluated.The 1,4-benzothiazine intermediates, which by Gould-Jacobs quinoline synthesis produced pyridobenzothiazine acids, were prepared by hydrolytic basic cleavage of substituted 2-aminobenzothiazoles and successive cyclocondensation with 1-bromo-2-chloroethane or alternatively with monochloroacetic acid, hence reduction by LiAlH4.The pyridobenzothiazine acids 10c, 30, and 31 show potent antibacterial activities against Gram-positive and Gram-negative pathogens.Structure-activity relationships are discussed.The compound 9-fluoro-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido<1,2,3-de><1,4>benzothiazine-6-carboxylic acid (31) (MF-934) has been found to possess, together with the antibacterial activity, a weak acute toxicity and interesting pharmacokinetic characteristics in several animal species (rat, dog, monkey, man).