| abstract |
A process for the manufacture of a symmetrical, terminally ring-substituted polyene comprises reacting a polyene di(O,O-dialkyl acetal) with a cyclic dienol ether in the presence of a Lewis or Brönsted acid, hydrolyzing the condensation product resulting therefrom and cleaving off alcohol under basic or acidic conditions from the polyene derivative produced at this stage. The novel cyclic dienol ethers as well as the likewise novel intermediates resulting from the condensation and the further intermediates in this process form further aspects of the invention. The final products are primarily carotenoids which find corresponding use, e.g. as colourings and pigments for foodstuffs, animal products etc. |