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Gilbert Stork developed strategies for selective organic synthesis, including enamine alkylation. An enamine provides a way to form a new carbon–carbon chemical bond at a chosen position, linking a temporary nitrogen-containing intermediate with the construction of a carbon skeleton. His oral history describes this work alongside polyene cyclization and the synthesis of natural products.^[ref]

A polyene cyclization converts a chain containing several carbon–carbon double bonds into one or more rings. A suitable initiating event can generate a reactive centre that attacks a later double bond, producing another reactive centre and allowing a cascade of ring closures.

The folded chain's geometry helps determine which rings and stereogenic centres form. In biosynthesis, enzyme-controlled cyclization of precursors related to squalene constructs complex steroid frameworks. The double bonds need not all belong to one continuous conjugated system. A plausible drawn cascade also needs compatible reaction kinetics and a three-dimensional conformation; connectivity alone does not guarantee that a proposed sequence occurs.