Novel oxazine derivatives and their use in the treatment of disease

A compound of formula (I), or a pharmaceutically acceptable salt thereof,

• wherein
• R1 and R2 are independently hydrogen or halogen;
• R3 and R4 are independently hydrogen or C1-3alkyl;
• or R3 and R4 taken together are cyclopropyl;
• or R1 and R4 are hydrogen and R2 and R3 taken together are —CH2—O—CH2—;
• R5 is C1-3alkyl, halogen-C1-3alkyl or C1-3alkoxy-C1-3alkyl;
• and
• R6 is phenyl or a 5- or 6-membered monocyclic heteroaryl comprising 1, 2, 3 or 4 heteroatoms independently selected from N, O and S, and wherein said phenyl or heteroaryl is optionally substituted by 1, 2, 3 or 4 substituents independently selected from halogen, cyano, amino, hydroxy, C1-4alkyl, halogen-C1-4alkyl, halogen-C1-4alkylthio, halogen-C1-4alkoxy, C1-4alkoxy, C1-4alkoxy-C1-4alkyl, C1-4alkoxy-C1-4alkoxy, C1-4alkoxy-C1-4alkylthio, C1-4alkoxy-C2-4alkenyl, C1-4alkoxy-C2-4alkynyl, hydroxy-C1-4alkyl, hydroxy-C2-4alkenyl and hydroxy-C2-4alkynyl.