The present invention relates to a process for preparing 6-hydroxy-3-[3-hydroxy-3- methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohexa-2,5-dien-1 -one of the formula (I). The invention also relates to 6-hydroxy-3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4- trimethyl-cyclohexa-2,5-dien-1 -one having a high E/Z-ratio of at least 80:20 and to the use thereof as a starting material for the preparation of astaxanthin or astacene. (l), (ll) The process comprises the reaction of the compound of formula (II), namely 6-hydroxy- 3-(3-hydroxy-3-methyl-pent-4-en-1 -ynyl)-2,4,4-trimethyl-cyclohex-2-en-1 -one, with a base. In this process, 1 E-isomer is formed with high selectivity, resulting in the compound of formula (I) with a E/Z-ratio of at least 80:20, in particular at least 90:10.
本发明涉及制备公式(I)的6-羟基-3-[3-羟基-3-甲基戊-1,4-二烯基]-2,4,4-三甲基
环己-2,5-二烯-1-酮的方法。本发明还涉及具有至少80:20的高E/Z比例的6-羟基-3-[3-羟基-3-甲基戊-1,4-二烯基]-2,4,4-三甲基
环己-2,5-二烯-1-酮及其作为制备
虾青素或虾青烯的起始原料的用途。该方法包括将公式(II)化合物与碱反应。在此过程中,高选择性地形成1个E-异构体,导致公式(I)化合物具有至少80:20的E/Z比例,特别是至少90:10。