Reaction of 1-(het)aryl-3-bromoprop-2-ynones with furans in solid metal oxides or salts: cross-coupling or cycloaddition?

1-(Het)aryl-3-bromoprop-2-ynones react with 2-(2-furyl)pyrrole in the Al₂O₃ or K₂CO₃ dispersion (room temperature, 1 h) to afford the cross-coupling products either at the furan or pyrrole rings. Furan and 2-methylfuran with 3-bromo-1-phenylprop-2-ynone under the same conditions give the Diels–Alder cycloadducts, while furan-2-carbaldehyde andits acetals are inactive.