A domino palladium-catalyzed hydrogenation reaction was developed to construct 6H-benzo[c]chromene scaffold. Using Pd/C catalyst under H2 balloon, 6H-benzo[c]chromenes were obtained in nearly quantitative yields. However, using Pd(PhCN)2Cl2/DPEphos/AgBF4 as the catalytic system, spiro[benzo[c]chromene-6,2′-chroman]s were obtained in up to 91% yields.
