2-(2-Propynyloxy)tetrahydropyran is used as a reagent to synthesize (-)-Histrionicotoxin, a spiropiperidine toxin that is isolated from the skin extracts of a Columbian frog (Dendrobates histrionicus). 2-(2-Propynyloxy)tetrahydropyran is also used as a reagent to prepare (-)-Exiguolide, a 16-membered macrolide that is used as a fertilization inhibitor.