Summary. New catalytic systems have been found which effect the isomerization of ccacetylenic alcohols to the corresponding a,P-unsaturated carbonyl compounds with high efficiency. These are combinations of silylvanadates with silanols or silanediols.u,p-Unsaturated carbonyl compounds, important intermediates in the manufacture of fragrances [l], carotenoids, and vitamins [Z] [6] and some contradictory reports [7]. Such rearrangements have been achieved by the use of a wide variety of acidic reagents [5] [6] [8] which often lead to complex mixtures of products. Meyer-Schuster RupsRearrangements of esterified acetylenic alcohols, however, proceed in high yield in the presence of certain transition metals [9] in charge induced [3s, 3s]-sigmatropic reactions [ l O j [ll], and the intermediates saponify cleanly to cr,P-unsaturated carbonyl compounds. Such a reaction has provided an important technical process for the manufacture of citral (2 $-3) from dehydrolinalool (1).