Catalytic annulation of 1-substituted-3-en-1-yn-5-als with cycloalkanones using acid–base dual catalysts

CpRu(PPh3)2Cl and DBU dual catalysts in combination enable a one-pot annulation of 1-R-3-en-1-yn-5-als (R = aryl, alkenyl, alkyl) and cycloalkanones to give highly substituted benzene products. This catalytic reaction consists of a tandem aldol condensation, dehydration and aromatization through a 1,7-hydrogen shift; the resulting 1-indanones and α-tetralones are obtained in moderate to good yields.