Explore multi-step organic synthesis routes with step-by-step mechanism breakdowns.
Multi-step organic synthesis is where individual named reactions stop being isolated facts to memorize and become tools you combine strategically to build a target molecule — the culminating skill tested in IChO organic problems and advanced Orgo coursework.
Working backward from the target molecule (retrosynthetic analysis) is usually more productive than working forward: identify the final bond or functional group that needs to be installed, ask what reagent could install it, and repeat until you reach available starting materials. The classic benzene-to-aniline route illustrates this clearly: aniline (an amine on a benzene ring) cannot be made by direct amination, so the actual route goes through nitration (installing -NO2 via electrophilic aromatic substitution with HNO3/H2SO4) followed by reduction (converting -NO2 to -NH2, typically with H2/Pd or Sn/HCl).
The benzene-to-phenol route via diazonium chemistry showcases a different strategy entirely: aniline is first converted to a diazonium salt (ArN2+) using NaNO2/HCl at low temperature, and this diazonium intermediate is a remarkably versatile synthetic handle — hydrolysis gives phenol, but the same intermediate can instead undergo azo coupling with another aromatic ring to build dyes, or a Sandmeyer reaction with CuCl/CuBr/CuCN to install halogens or nitriles that are otherwise difficult to introduce directly onto a benzene ring.
Grignard reagents (RMgX) are the workhorse for forming new carbon-carbon bonds: they attack the electrophilic carbon of an aldehyde or ketone, and after aqueous workup, produce secondary or tertiary alcohols. Aldol condensation is the other major carbon-carbon bond-forming strategy, where an enolate (formed by deprotonating alpha to a carbonyl) attacks a second carbonyl compound, ultimately eliminating water to form an alpha,beta-unsaturated carbonyl product.
This synthesis pathway tool breaks each multi-step route into individual steps with the specific reagents and conditions required, showing exactly how reagent and condition choice at each stage determines whether the target molecule is actually reached.