| abstract |
2,5-bis (1 ', 1'-dialkoxy-2'-propyl) -2,5-dihydrofurane of the general formula I. in which R¹ and R² may be the same or different and may represent an alkyl group having 1 to 4 carbon atoms, the preparation of which by reacting 2,5-dialkoxy-2,5-dihydrofurans of the formula II in the presence of protonic acids or Lewis acids with an alkyl propenyl ether of the formula III and their use for the preparation of 2,7-dimethyl-octa-2,4,6-triene-1,8-dial and of symmetrical C₄₀-carotenoids, such as β-carotene, canthaxanthin and astaxanthin. |