Racemic and optically active 3-hydroxy-alpha-cyclocitral, its acetals and optically active 3-oxo-alpha-cyclocitral acetals, and their preparation

Abstract

3-Hydroxy-.alpha.-cyclocitral derivatives of the general formula I ##STR1## where R.sup.1 is ##STR2## wherein R.sup.2 and R.sup.3 can be identical or different and are each straight-chain or branched alkyl of 1 to 6 carbon atoms, or R.sup.2 and R.sup.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-.beta.-cyclocitral, as well as optically active - cyclocitral derivatives of the general formulae A and B ##STR3## where R.sup.1 is ##STR4## if X is hydrogen and Y is OH, but is otherwise ##STR5## where R.sup.2 and R.sup.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-.alpha.-cyclocitral acetals, wherein a mixture of the corresponding racemic 3-oxo-.alpha.-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-.beta.-cyclocitrals, which are desirable because they are important intermediates for carotinoids identical to the natural products.

Dependencies are inferred from the claim text.