Catalytic hydrogenation of 3‐benzyloxycarbonylaminoazino[1,2‐x]‐azin‐4‐ones. A facile access to 3‐amino‐6,7,8,9‐tetrahydro‐4H‐pyrido[1,2‐a]pyridin‐4‐ones and 3‐Amino‐6,7,8,9‐tetrahydro‐4H‐azino[1,2‐x]pyrimidin‐4‐ones