Hoffmann-la Roche Inc.

Hansjorg Grass

Erich Widmer

Reinhard Zell

A process for the manufacture of 3-hydroxy-2-cycloalken-1-one derivatives by cathodically reducing a compound of the general formula ##STR1## wherein n is the integer 0 or 1, to a compound of the formula ##STR2## wherein n has the above significance, and, if desired, further cathodically reducing the resulting compound in acidic or neutral medium to a compound of the general formula ##STR3## wherein n has the above significance.

Process for the manufacture of 3-hydroxy-2-cycloalken-1-one derivatives

A process for the manufacture of the novel compound of the formula ##STR1## from the compound of the formula ##STR2## is described. This process comprises cathodically reducing the compound of formula I in a basic, aqueous-organic solvent mixture. The compound of formula II is an intermediate in the manufacture of rhodoxanthin or zeaxanthin.

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Muttenz, Switzerland

Hansjorg Grass