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Cephalosporin C is a fungal natural product in the beta-lactam antibiotic family, with formula ${\mathrm{C}}_{16}{\mathrm{H}}_{21}{\mathrm{N}}_3{\mathrm{O}}_8\mathrm{S}$. Its framework contains a strained four-membered cyclic amide fused to a sulfur-containing six-membered ring.^[ref]

For synthetic chemistry, the challenge is the combination of reactive rings, several functional groups and defined stereochemistry. Making the correct elemental formula is therefore a much weaker test than constructing the complete structure. This compound supplies a concrete example of why total synthesis needs control over connectivity and spatial arrangement together.

Robert Burns Woodward developed strategies for the total synthesis of structurally complex natural products. His 1965 Nobel lecture uses the synthesis of cephalosporin C to explain the problems of constructing a target's carbon skeleton, arranging functional groups, and controlling stereochemistry. The synthesis becomes an argument about molecular structure as well as a route to a substance.^[ref]