Efficient domino process based on the catalytic generation of non-metalated, conjugated acetylides in the presence of aldehydes or activated ketones

The extremely mild and highly efficient catalytic generation of non-metalated, conjugated acetylides is reported. These acetylides are used to generate enol-protected functionalized propargylic alcohols 1, 1,3-dioxolane compounds 2, or 3,4,5-trisubstituted 4,5-dihydrofurans 4 through serial multi-bond-forming processes. The method calls for a nucleophile (a tertiary amine or phosphine) as a chemical activator, a conjugated terminal acetylene as the acetylide source, and an aldehyde or activated ketone as the electrophilic partner. The chemical outcome of this process depends on the nature of the nucleophile, the temperature, stoichiometry and solvent, and it can be tailored selectively by the appropriate choice of the experimental conditions.