A system and method for automated retrosynthesis which can reliably identify valid and practical precursors and reaction pathways. The methodology involves a k-beam recursive process wherein at each stage of recursion, retrosynthesis is performed using a library of molecule disconnection rules to identify possible precursor sets, validation of the top k precursor sets is performed using a transformer-based forward reaction prediction scoring system, the best candidate of the top k precursor sets is selected, and a database is searched to determine whether the precursors are commercially available. The recursion process is repeated until a valid chain of chemical reactions is found wherein all precursors necessary to synthesize the target molecule are found to be commercially available.