SynthEx AI designs natural product syntheses experts rank alongside human chemists

SynthEx, an agentic framework built on large language models, plans synthesis routes to complex natural products that lie beyond the reach of conventional design algorithms, according to the article. It proposes competing strategies, assembles routine and key steps into a cohesive route, and critiques and improves its own design. The chemistry it favors is more convergent than existing tools produce and spans a region of reaction space that catalogue-based tools cannot match. In blinded assessments, expert chemists judged its key steps comparable to those of published human syntheses and engaged with them as genuine synthesis plans. The authors release routes to more than a thousand natural products as SynthAtlas, an open, interactive database, and anticipate it will become a shared resource for a collection of complex target molecules that lack existing literature routes.