The Pd-catalyzed isomerization of primary allylic alcohols into the corresponding saturated aldehydes has been achieved at room temperature for the first time in good to excellent yields under mild conditions. The functional group compatibility in this reaction is studied, and this new methodology has been successfully applied in the synthesis of a C5-C13 tetrahydropyran ring system of (-)-brevisamide in seven steps.

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Primary allylic alcohols are isomerized to aldehydes in the presence of Pd(OH) 2 and homologated to a,b-unsaturated carbonyl derivatives in one-pot by addition of stabilized Wittig ylides in a sequential fashion. When the reaction was prolonged by addition of more catalyst, a hydrogenation step succeeds the Wittig olefination. In addition, sequential isomerization-Wittig olefination-oxaMichael addition reaction provides tetrahydropyran with high diastereoselectivity.

A one-pot, three-component synthesis of 2-amino-2-chromenes is described at ambient temperature by the reaction of an aldehyde and malononitrile or ethyl cyanoacetate with a-naphthol or b-naphthol in ethanol in presence of a catalytic amount of Triton B.

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