| abstract |
3-Hydroxy-α-cyclocitral derivatives of the general formula I ##STR1## where R 1 is ##STR2## wherein R 2 and R 3 can be identical or different and are each straight-chain or branched alkyl of 1 to 6 carbon atoms, or R 2 and R 3 together form an ethylene or propylene group which can be substituted by methyl or ethyl, processes for their preparation and their use for the preparation of safranal and 3-hydroxy-β-cyclocitral, as well as optically active - cyclocitral derivatives of the general formulae A and B ##STR3## where R 1 is ##STR4## if X is hydrogen and Y is OH, but is otherwise ##STR5## where R 2 and R 3 have the above meanings, and X and Y together are oxygen, or X is hydrogen if Y is OH, and a process for the preparation of optically active 3-oxo-α-cyclocitral acetals, wherein a mixture of the corresponding racemic 3-oxo-α-cyclocitral acetals is separated into the optically active compounds by chromatography over a suitable chiral adsorbent. The novel compounds open up a novel advantageous route to optically active 3-hydroxy-β-cyclocitrals, which are desirable because they are important intermediates for carotinoids identical to the natural products. |