Natural acetylenes. Part XXXI. C14-tetrahydropyranyl and other polyacetylenes from the compositae Dahlia coccinea Cav. var. coccinea

Abstract

The polyacetylene contents of one form of the species Dahlia coccinea Cav. var. coccinea and also of a horticultural form derived from the same species have been examined. The nineteen polyacetylenes detected comprised eight C₁₃, eight C₁₄, and three C₁₇ compounds. Five of them were previously unknown; their isolation, characterisation, and structure determination are described. They are the C₁₄ 2,3-disbustituted tetrahydroprans CH₃·[CC]₃·CH[graphic omitted]CH·[graphic omitted] and CH₃·CH[graphic omitted]CH·[CC]₂·CH[graphic omitted]CH·[graphic omitted] (R = H or Ac), and the C₁₇ acetate CH₃·CH[graphic omitted]CH·[CC]₂·[CH[graphic omitted]CH]₂·CH(OAc)·[CH₂]₃·CHCH₂.