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