Abstract: There is described a compound of general formula (2RS,4SR,6X)-2,4,6-Rimethyl-4-phenyl-1,3-dioxane with the configuration characteristic X=RS (Compound 1) or SR ##STR1## The compounds 1 and 3 possess a fragrance which can be described as strong, herbal-fresh, green, typically grapefruit.Further described are new processes for production of a mixture of the compounds (2RS,4SR,6RS)-2,4,6-trimethyl-4-phenyl-1,3-dioxane (1) and (2RS,4RS,6RS)-2,4,6-trimethyl-4-phenyl-1,3-dioxane (2).

Abstract: It was found that 8-exo-formyl-2,6-exo-tricyclo[5.2.1.0.sup.2,6 ]decane having the constitution and stereochemistry of formula (I) possesses particularly useful olfactory properties which are clearly superior to those of the 8-endo-epimer and which already have an effect if compound (I) is enriched with mixtures of 8-exo- and 8-endo-epimers. Compound (I) can therefore be advantageously used, in pure or enriched form, as a scent or as a component of perfume compositions. To prepare an enriched epimer mixture, a mixture obtained in a known manner (U.S. Pat. No. 3,270,061) and having an exo/endo ratio of 1.45:1 is brought into equilibrium by base catalysis, preferably by the action of alkali hydroxides in alcoholic solution, to give an exo/endo ratio of 5.25:1. Alternatively, the enriched epimer mixture can be prepared starting from 8-formyl-2,6-exo-tricyclo[5.2.1.0.sup.2,6 ]decene-3(4), catalytically hydrogenated for example with palladium coal and then optionally brought into equilibrium.