The synthetic accessibility score (SA score) is a calculated value that approximates the feasibility of a molecule to be synthesized. SA score is calculated by the difference between fragment score and complexity penalty. The fragment score indicates the structural features viability of synthesized and is calculated as a sum of contributions of all fragments contained in the molecule. The complexity score is the sum of ring complexity (ring bridge atoms and spiro atoms), large rings, stereocenters, and molecular size. SA score was computed using the Python script of Ertl and Schuffenhauer. 41