New terpene hydrocarbons from the alligatoridae (crocodylia, reptilia).

The contents of the paracloacal gland secretions of the alligatorids Alligator mississippiensis, A. sinensis, Paleosuchus palpebrosus, and P. trigonatus were investigated. Novel acyclic hydrocarbon terpenes with a rare trisubstituted 2,4-diene system were identified in the secretions of A. sinensis, P. palpebrosus, and P. trigonatus. The structures of the monoterpene (2E,4E)-3,7-dimethyl-2,4-octadiene (9) and the sesquiterpene (2E,4E,7S)-3,7,11-trimethyl-2,4-dodecadiene (14) were proven by synthesis and gas chromatography on a chiral phase. Several other new terpenes (11, 16, 17, 18, 19, and 20) related to these components also were present in the secretions, as well as the known compounds myrcene (6), (E)-beta-farnesene (4), (E)-beta-springene (3), squalene (5), cembrene A (1), and 11,12-dihydrocembren-10-one (2).