Acetylene as driving and organizing molecule in the assembling reactions with chalcones in the NaOBut/DMSO superbase system

Acetylene reacts with chalcones in the NaOBu^t / DMSO superbase system (3–12 atm, 70°C, 15 min) to give, along with substituted furans, functionalized 3-exo-aryl-7-methylidene- 6,8-dioxabicyclo[3.2.1]octanes, novel frontalin congeners, which are diastereoselectively assembled from two molecules of chalcones and one molecule of acetylene.