We don't have synonyms for diterpenes yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are diterpene, terpenes and triterpenes.
(n) :
(organic chemistry) any terpene formed from four isoprene units, and having twenty carbon atoms; includes vitamin A, the gibberellins, and various biologically active lactones such as quassin.
(n) :
(organic chemistry) any terpene formed from four isoprene units, and having twenty carbon atoms; includes vitamin A, the gibberellins, and various biologically active lactones such as quassin.