Synthesis of polychloromethylated and halogenated spiro[5,5]trienones via dearomative spirocyclization of biaryl ynones.

We disclosed a selective polychloromethylation and halogenation reaction of alkynes via a radical addition/spirocyclization cascade sequence, in which polyhaloalkanes were used as the precursor for polyhalomethyl and halogen radicals. Using this strategy, a series of valuable halogen-, CHCl2- or CCl3-containing spiro[5,5]trienones were synthesized in good yields with good functional group tolerance in one pot under simple and mild conditions. It is noted that an unprecedented halogenation instead of dibromomethylation was achieved when CH2Br2 was used in this work.