In drug discovery, a chemical compound should possess multiple properties in addition to biological activity, to be advanced as a clinical candidate. A compound identified to exhibit therapeutic activity, known as a hit, is being structurally modified to address liabilities, such as inadequate solubility and activity through a long and iterative process. During that stage, medicinal chemists apply transformations on the starting molecule to design analogues based on the intuition they develop or through reaction-based library enumeration. Given the vast size of the chemical space, it becomes significantly challenging to exhaustively evaluate the chemical space for a given objective even for a single molecule. Computational methods for targeted molecule generation can greatly support the exploration of the chemical space in a time-efficient manner and recommend structures previously unexplored by chemists.