retrosyntetinen

Retrosyntetinen, commonly referred to in English as retrosynthesis, is a method in organic chemistry for planning the preparation of complex molecules by working backward from the target. The core idea is to identify strategic bond disconnections in the target that reveal simpler precursor structures which could be assembled through known reactions.

Practitioners apply a set of disconnection templates or reaction rules to generate a tree of possible precursors, a process known as retrosynthetic analysis. Each step replaces a fragment of the target with a simpler equivalent until readily available starting materials are reached. The approach emphasizes functional group interconversions, protecting-group considerations, and the aim to favor convergent, scalable routes over long linear sequences.

Retrosynthesis was popularized by Elias James Corey in 1969, who formalized the method as a systematic tool for synthesis planning. Since then it has become a central concept in both academic research and pharmaceutical development.

In practice, retrosynthetic planning combines chemical intuition with data-driven methods. Computer-aided synthesis planning systems attempt to automate disconnections, but the field still relies on human expertise to judge practicality, selectivity, and available laboratory capabilities. Limitations include incomplete reaction knowledge, uncertain yield estimates, and the possibility that proposed routes are impractical at scale.

The term retrospectivinen or retrosyntetinen reflects the Finnish rendering of the concept; in English-language literature the standard term is retrosynthesis.