The invention provides a process for the production of a compound of formula (A), or a pharmaceutically acceptable salt or solvate thereof, wherein R1 represents C¿1-4? alkoxy optionally substituted by one or more fluorine atoms; R?2¿ represents H or C¿1-6? alkoxy optionally substituted by one or more fluorine atoms; R?3¿ represents a 5- or 6-membered heterocyclic ring which is optionally substituted; R4 is a 4-, 5-, 6- or 7-membered heterocyclic ring which is optionally fused to a benzene ring or a 5- or 6-membered heterocyclic ring, the ring system as a whole being optionally substituted; the process comprising condensing a compound of formula (B), wherein R1 to R3 are as defined above; with a compound of formula (C), wherein R?5 and R6¿ taken together with the N atom to which they are attached represent a 4-, 5-, 6-, or 7-membered N-containing heterocyclic ring, the ring being optionally fused to a benzene ring or a 5- or 6-membered heterocyclic ring, the ring system as a whole being optionally substituted.