Aminodihydrothiazine derivatives substituted with a cyclic group

A compound of the formula (I):

• wherein the ring A is an optionally substituted carbocyclic group or an optionally substituted heterocyclic group,
• R1 is optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted lower alkynyl, an optionally substituted carbocyclic group or an optionally substituted heterocyclic group,
• R2 a and R2 b are each independently hydrogen, optionally substituted lower alkyl or optionally substituted acyl,
• R3 a, R3 b, R3 c and R3 d are each independently hydrogen, halogen, hydroxy, optionally substituted lower alkyl, optionally substituted lower alkenyl, optionally substituted acyl, optionally substituted lower alkoxy, optionally substituted carbocyclyl lower alkyl, optionally substituted heterocyclyl lower alkyl, optionally substituted carbocyclyl lower alkoxy, optionally substituted heterocyclyl lower alkoxy, optionally substituted aralkyl, optionally substituted heteroaralkyl, optionally substituted aralkyloxy, optionally substituted heteroaralkyloxy, optionally substituted lower alkylthio, carboxy, optionally substituted lower alkoxycarbonyl, optionally substituted amino, optionally substituted carbamoyl, an optionally substituted carbocyclic group or an optionally substituted heterocyclic group, or
• R3 a and R3 b or R3 c and R3d may form a carbocyclic ring together with a linked carbon atom or may form oxo,
• provided the following compounds i) and ii) are excluded;
• i) a compound in which R2 a is hydrogen, R2 b is hydrogen, acetyl or phenyl, R1 is methyl, and the ring A is phenyl or 4-methoxyphenyl;
• and
• ii) a compound in which R2 a is hydrogen, R2 b is hydrogen, acetyl or phenyl, R1 is ethyl and the ring A is 3,4-dimethoxyphenyl;
• a pharmaceutically acceptable salt or solvate thereof.