Palladium catalysed reactions of allene with active methylene pronucleophiles. C-1,3-Dienylmethyl derivatives and their Diels–Alder reactions

A 2-step 100% atom economic sequence is reported whereby active methylene pronucleophiles react with 2 mol equiv. of allene to give bis-1,3-dienylmethyl derivatives of the pronucleophiles. Subsequent double Diels–Alder reactions furnish 1,1′-linked cyclohexenes with a 3-carbon spacer.