Computational Chemist

Ideation Beyond Search

Forward Synthesis

SA Score

Forward Synthesis for Computational Chemists

Forward Synthesis is a computational tool that lets chemists create and evaluate molecular libraries before running synthesizability screenings, operating across two dimensions: the core skeleton that defines a molecule's structural foundation, and the synthetic route that determines how it can be built.
ChemAIRS® is designed to help chemists rapidly generate large-scale molecular libraries while ensuring every molecule in that library is actually feasible to synthesize. It analyzes the core structure to identify where modifications can be introduced without breaking core integrity, then filters out structures prone to instability, degradation, or toxicity risk by evaluating reactivity, functional group compatibility, and safety profiles - so the library that comes out the other side is both diverse and realistic, not just diverse.

SA Score for Computational Chemists

SA Score is a measure of how difficult a molecule is likely to be to synthesize, based on structural complexity and similarity to known synthesizable compounds. It gives medicinal chemists a way to compare analogs by makeability before deciding which ones are worth pursuing.
ChemAIRS® evaluates hundreds of thousands of molecules in hours, ranking them by synthetic accessibility so large virtual libraries can be screened overnight rather than compound by compound. Reaction logic and step efficiency, building block availability, and starting material cost are all factored into the ranking, so the output reflects real-world feasibility, not just structural complexity. In a 1,346-molecule validation study, ChemAIRS® matched Merck's expert synthesis team, and its AI-driven assessments identified viable intermediates that human experts had overlooked.

SA Score in Practice:

Technical Comparison

8 Mainstream Synthetic Accessibility Prediction Models

A technical comparison

Read the comparison

Generative and virtual screening workflows can produce thousands of candidate structures, but not every structure on paper is realistic to make. ChemAIRS® screens large virtual libraries for synthetic accessibility and reaction feasibility, helping computational chemists prioritize candidates that are both novel and achievable, not just theoretically interesting.