1,3-Polyol arrays via the stereoselective rearrangement of vinyl acetals

A series of 1,3-dioxanyl vinyl acetals were readily synthesized from the corresponding dioxanone by a reduction and in situ acylation followed by Petasis olefination. Treatment of these vinyl acetals with BF3·OEt2 results in an O to C rearrangement to form anti-3,5-dihydroxyketones while a mixture of Me3Al and BF3·OEt2 provides the corresponding syn relationship via a stereoretentive rearrangement.