Superbase-Catalyzed Steric-Hindrance-Induced Dimerization of Alkynones to Highly Functionalized Furans

The cascade dimerization of alkynones bearing sterically hindered secondary alkyl groups at the carbonyl function has unexpectedly furnished highly functionalized furans. The reaction efficiently occurs in the presence of potassium tert-butoxide/dimethylsulfoxide superbase catalytic system at room temperature. Alkynones having additional C−H active site at the carbon-carbon triple bond have followed another dimerization pathway to afford 3-alkenylpyran-4-ones. The discovery of these reactions expands the traditional knowledge about the reactivity of alkynones in strong basic medium.