reaction of benzyl bromide with sodium cyanide. Strategies Functional group strategies Manipulation of functional groups can lead to significant reductions in molecular complexity. Stereochemical strategies Numerous chemical targets have distinct stereochemical demands. Stereochemical transformations (such as the Claisen rearrangement and Mitsunobu reaction) can remove or transfer the desired chirality thus simplifying the target. Structure-goal strategies Directing a synthesis toward a desirable intermediate can greatly narrow the focus of analysis. This allows bidirectional search techniques. Transform-based strategies The application of transformations to retrosynthetic analysis can lead to powerful reductions in molecular complexity. Unfortunately, powerful transform-based retrons are rarely present in complex molecules, and additional synthetic steps are often needed to establish their presence. Topological strategies The identification of one or more key bond disconnections may lead to the identification of key substructures or difficult to identify rearrangement transformations in order to identify the key structures. Disconnections that preserve ring structures are encouraged. Disconnections that create rings larger than 7 members are discouraged. Disconnection involves creativity. See also Organic synthesis Total synthesis References External links Centre for Molecular and Biomolecular Informatics Presentation on ARChem Route Designer, ACS, Philadelphia, September 2008 for more info on ARChem see the SimBioSys pages. Manifold, Software freely available for academic users developed by PostEra Retrosynthesis planning tool: ICSynth by InfoChem Spaya, Software freely available proposed by Iktos Chemical synthesis Organic chemistry Chemical reaction engineering