A Facile Method for the Bishomologation of Ketones to α,β-Unsaturated Aldehydes: Application to the Synthesis of the Cyclohexanoid Components of the Boll Weevil Sex Attractant

Abstract

The acid-catalyzed isomerization of tertiary vinyl carbinols (2) to the corresponding primary allylic alcohols (5) has been reported numerous times in the chemical literature.¹ In addition, the corresponding acetylenic carbinols (3) have been shown² to rearrange to α,β-unsaturated aldehydes (6) when treated with aqueous acid. Since yields are generally low under the conditions required for the latter transformation, a better method³ involves the isomerization of the corresponding tertiary acetylenic acetate (4) in the presence of silver ion to an allenic acetate, followed by hydrolysis to the desired α,β-unsaturated aldehyde (6).