2,4,6,8-Tetraoxa-5-phosphanonanedioic acid,5-[2-[[[7-(cyclohexylamino)-1-(1-ethylpropyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinolinyl]carbonyl]amino]ethyl]-, bis(1-methylethyl) ester, 5-oxide