1-(2-Cyclopropylethyl)-3-[1,1-dioxo-7-(5-oxo-4,5-dihydro-isoxazol-3-yl)-1,4-dihydrobenzo[1,2,4]-thiadiazin-3-yl]-6-fluoro-4-hydroxy-1H-quinolin-2-one AIDS-221844 AIDS221844