Improved process for the production of astaxanthin, new intermediates therefor and a process for their production.

摘要

Compounds of the general formula I in which R<1> is H or C1-C4-alkyl, R<2> is C1-C4-alkyl and R<3> is an ether, silyl ether or acetal protective group which can be converted into a hydroxyl group by hydrolysis, in particular one of the radicals and a process for the production of these compounds by reacting an alkenyne of the general formula II in an inert solvent with additional use of lithium amide with a cyclohexenone of the general formula III and the use of the compounds of the formula I for the production of astaxanthin.