Odoriferous constituents of Dictyopteris

Abstract

The genus Dictyopteris is one of the few genera of seaweeds possessing odor. Its essential oil is composed of C11 hydrocarbons. The isolation and identification of eight hydrocarbons, viz. dictyopterene A [(+)-(R,R)-trans-l-(trans-hex-l'-enyl)-2-vinylcyclopropane (1)], dictyopterene B [(-)-(R,R)-trans-l-(trans,cis-hexa-l',3'-dienyl)- 2-vinylcyclopropane (2)], trans, cis, cis-undeca-l,3,5,8- tetraene (3), trans,trans,cis-undeca-l,3,5,8-tetraene (4), trans, cis-undeca-l,3,5-triene (5), trans,trans-undeca-l,3,5-triene (6), dictyopterene C' [(-)-(R)-6-butylcyclohepta-l,4-diene (7)], and dictyopterene D' [(+)-(S)-6-(cis-but-l'-enyl)-cyclohepta-l,4-diene (8)] are described.^(1,2,3,4) The compounds were separated by gradient chromatography on silver nitrate-silica gel and gas chromatography and were identified by spectroscopic and chemical methods. Biogenesis of the hydrocarbons is discussed. The thermal Cope rearrangements of 1→9 and 2→10 have been shown to be stereospecific and to involve a diradical intermediate. Compounds 9 and 10 were found to be identical in all respects except optical properties with 7 and 8 respectively.