Divergent Synthesis of 3-Hydroxyfluorene and 4-Azafluorene Derivatives from ortho-Alkynylarylketones.

A divergent synthesis of 3-hydroxyfluorene and 4-azafluorene derivatives has been developed. ortho-Alkynylarylketone was employed as the substrates to react with molecular iodine leading to the generation of a common intermediate, indenone precursor. This precursor could lead to the diversified products when the reaction was carried out under different conditions. The indenone intermediate was converted to the corresponding 3-hydroxyfluorene products under basic conditions while the reaction in the presence of ammonium salt provided 4-azafluorene products. This divergent method could be applied to a broad range of substrates to give the corresponding products in moderate to good yields.