36.1.2—Devise multi-step synthetic routes

A synthetic route is a sequence of syllabus reactions that converts an available starting material into a target. Work backwards from the target group, choose a compatible precursor, then check that each reagent and condition is selective.

Record the transformation at every arrow and keep track of carbon count, oxidation state and side products. Shorter routes are not automatically better if they violate conditions.

To make an ester, choose a carboxylic acid plus alcohol (equilibrium route) or an acyl chloride plus alcohol (rapid route), then select how each precursor can be prepared.

A route is not justified by naming familiar reagents; every step must match a structural change and preserve the rest of the molecule.