Synthesis of α,β-Unsaturated Ketones from Aldehydes and Ketones Using 1,1-Di(boryl)alk-1-enes

α,β-Unsaturated ketones are important functional groups that are widely used in various fields such as chemi-cal synthesis and molecular biology. Here we report an efficient method for the synthesis of α,β-unsaturated ketones through the boron-Wittig reaction of aldehydes and ketones using 1,1-di(boryl)alk-1-enes as building blocks which are pre-pared from terminal alkynes including propyne. 1,1-Di(boryl)alk-1-enes are deprotonated at the γ-position to generate α,α-di(boryl)allyl anions, which react with aldehydes and ketones at the α-position to give boryl-1,3-dienes. Subsequent oxida-tion of the resulting boryl-1,3-dienes produces α,β-unsaturated ketones. Furthermore, α,β,γ,δ-unsaturated ketones were also synthesized using 1,1-di(boryl)alka-1,3-dienes. The synthetic utility of this method is demonstrated by an application to the concise syntheses of two natural products.