(6R)-6-({4-[(6,7-dihydro[1,4]dioxino[2,3-c]pyridazin-3-ylmethyl)amino]-1-piperidinyl}methyl)-3-fluoro-5,6-dihydro-8H-[1,4]thiazino[2,3,4-de]-1,5-naphthyridin-8-one

3-fluoro-6-(methyloxy)-1,5-naphthyridine-4-thiol